Medical School · Year 3 · Psychiatry · includes a quiz and discussion video

Seminar 18: Consultation-Liaison Psychiatry

Psychiatry Clerkship

Learning Objectives

By the end of this seminar, students will be able to:

1. Define the scope and clinical approach of consultation-liaison psychiatry including the roles of consultant to the patient, the referring team, and the healthcare system
2. Evaluate delirium through systematic assessment of etiology, clinical features, and severity using standardized instruments and evidence-based management
3. Assess decision-making capacity using the four-component model and apply it to common clinical scenarios in medically hospitalized patients
4. Identify the psychiatric manifestations of common medical conditions and the medical causes of psychiatric symptoms requiring differential diagnosis
5. Manage depression, anxiety, and adjustment disorders in the medically ill population with attention to drug interactions and organ-specific prescribing considerations
6. Recognize and address coping difficulties, treatment non-adherence, and staff-patient conflicts through collaborative consultation approaches

Seminar Outline

Section 1: Principles of Consultation-Liaison Psychiatry

Consultation-liaison psychiatry, also termed psychosomatic medicine, is the subspecialty of psychiatry devoted to the care of patients with comorbid psychiatric and medical or surgical conditions, primarily in the general hospital setting. The consultation role involves evaluating specific clinical questions referred by medical or surgical teams, such as the assessment of depression, delirium, capacity, or suicidal ideation in a hospitalized patient. The liaison role involves proactive integration with medical teams to address the psychological and behavioral dimensions of medical illness, promote communication, and provide ongoing education about the psychiatric aspects of medical care. The field recognizes that psychiatric and medical conditions frequently co-occur, interact bidirectionally, and that comprehensive patient care requires attention to both domains.

The consultation process follows a structured approach that begins with understanding the referring team's question and ends with the delivery of actionable recommendations. Upon receiving a consultation request, the psychiatrist should first clarify the specific clinical question, as vague requests such as "psych consult" may obscure the actual concern. A thorough review of the medical record provides essential context including the medical diagnosis, current medications, recent laboratory results, and any previous psychiatric history. The patient interview should address both the psychiatric presentation and the patient's understanding of and emotional response to their medical condition. Communication of findings and recommendations to the referring team should be clear, specific, and practical, avoiding jargon and providing concrete management steps rather than merely diagnostic labels. Follow-up is essential for complex cases, as the patient's clinical status and the team's needs may evolve during the hospitalization.

The biopsychosocial model is particularly relevant in consultation-liaison psychiatry, where the interaction between biological, psychological, and social factors is immediately apparent. Biological factors include the direct neuropsychiatric effects of medical illness, the psychiatric side effects of medications, and the impact of physiological derangements on brain function. Psychological factors encompass the patient's emotional response to illness, coping style, personality traits, pre-existing psychiatric conditions, and the meaning the patient attributes to their illness. Social factors include the patient's support system, functional status, financial stressors, and the quality of the patient-provider relationship. The CL psychiatrist integrates these domains into a comprehensive formulation that guides both psychiatric and collaborative medical management.

Common reasons for psychiatric consultation in the general hospital reflect the prevalence of psychiatric comorbidity in medical settings. Delirium is the single most common reason for consultation, affecting approximately fifteen to twenty percent of general medical inpatients and up to fifty percent of those in intensive care units. Depression screening in patients with new diagnoses of cancer, cardiovascular disease, or neurological conditions represents a growing area of consultation. Capacity assessment is frequently requested when patients refuse recommended treatments, request discharge against medical advice, or need to provide informed consent for complex procedures. Suicide risk assessment is consulted when patients express suicidal ideation, engage in self-harm, or present after a suicide attempt. Other common reasons include agitation management, substance use evaluation, medication recommendations, and assistance with difficult patient-staff interactions.

<image>Panel A: Consultation-liaison psychiatry scope showing consultant and liaison roles, general hospital setting, bidirectional medical-psychiatric interaction, and subspecialty positioning within psychiatry. Panel B: Structured consultation process showing question clarification, medical record review, patient interview, biopsychosocial formulation, recommendation communication, and follow-up pathway. Panel C: Biopsychosocial model applied to medical settings showing biological factors of illness, medications, and physiology; psychological factors of coping, personality, and illness meaning; and social factors of support, function, and patient-provider relationships. Panel D: Common consultation reasons showing delirium prevalence at fifteen to twenty percent of medical inpatients, depression screening, capacity assessment, suicide risk evaluation, agitation, substance use, and staff conflicts.</image>

Section 2: Delirium Assessment

Delirium is an acute neurocognitive disorder characterized by disturbances in attention, awareness, and cognition that develop over hours to days, fluctuate in severity, and result from an underlying medical condition or its treatment. The DSM-5 diagnostic criteria require a disturbance in attention and awareness, acute onset with fluctuating course, an additional disturbance in cognition such as memory, orientation, language, or perception, evidence that the disturbance is a direct physiological consequence of a medical condition, and that the disturbance is not better explained by a pre-existing neurocognitive disorder. Delirium is associated with significant morbidity including prolonged hospitalization, increased risk of falls, accelerated cognitive decline, higher rates of institutionalization, and mortality rates of twenty-five to thirty-three percent during hospitalization. Despite its clinical significance, delirium remains underdiagnosed in approximately sixty to seventy percent of cases, largely because the hypoactive subtype, which is more common and carries a worse prognosis, is frequently overlooked.

The Confusion Assessment Method is the most widely used screening tool for delirium and assesses four features. Feature one is acute onset and fluctuating course, determined by asking whether there was an acute change in mental status from baseline and whether the behavior has fluctuated during the day. Feature two is inattention, assessed through tasks such as asking the patient to recite the days of the week backward, count backward from twenty, or maintain attention during digit span testing. Feature three is disorganized thinking, evaluated through the coherence and logic of the patient's verbal responses and the ability to follow simple commands. Feature four is altered level of consciousness, ranging from hyperalert to lethargic to stuporous to comatose. Delirium is diagnosed when features one and two are present along with either feature three or feature four. The CAM-ICU is an adaptation designed for intubated or non-verbal patients in intensive care settings.

Three clinical subtypes of delirium are recognized based on the predominant psychomotor pattern. Hyperactive delirium presents with agitation, psychomotor restlessness, emotional lability, hallucinations, and delusions, and is the most readily recognized variant because of its disruptive nature. Hypoactive delirium presents with lethargy, decreased psychomotor activity, reduced interaction with the environment, and is frequently misidentified as depression, fatigue, or oversedation. Mixed delirium alternates between hyperactive and hypoactive features within the same episode and is the most common pattern. The mnemonic I WATCH DEATH summarizes the major etiological categories that must be investigated: Infection, Withdrawal, Acute metabolic derangement, Trauma, CNS pathology, Hypoxia, Deficiencies in vitamins, Endocrine disorders, Acute vascular events, Toxins or drugs, and Heavy metals. The workup should include a targeted history, physical examination with neurological assessment, complete metabolic panel, complete blood count, urinalysis, chest radiograph, electrocardiogram, and additional studies guided by clinical suspicion.

Predisposing and precipitating factors interact to determine delirium risk, and a vulnerability-insult model helps conceptualize this interaction. Predisposing factors that increase baseline vulnerability include advanced age, pre-existing cognitive impairment or dementia, sensory deficits including visual and hearing impairment, functional impairment, history of prior delirium, severe medical illness, and frailty. Precipitating factors that act as acute insults include infection, medications particularly anticholinergics, benzodiazepines, opioids, and polypharmacy, surgery especially cardiac and orthopedic procedures, metabolic derangements, dehydration, immobilization, sleep deprivation, and environmental disruption including ICU admission. A patient with high baseline vulnerability requires only a minor precipitant to develop delirium, while a patient with low vulnerability may require a severe insult. This model has important implications for prevention, as addressing modifiable predisposing and precipitating factors can reduce delirium incidence by thirty to forty percent.

<image>Panel A: Delirium DSM-5 diagnostic criteria showing attention and awareness disturbance, acute onset with fluctuation, cognitive impairment, medical etiology requirement, and mortality rates with underdiagnosis prevalence. Panel B: Confusion Assessment Method showing four features of acute onset and fluctuation, inattention, disorganized thinking, and altered consciousness with diagnostic algorithm requiring features one and two plus three or four. Panel C: Delirium subtypes showing hyperactive features, hypoactive features with misidentification risk, and mixed pattern with I WATCH DEATH mnemonic for etiological workup. Panel D: Vulnerability-insult model showing predisposing factors of age, dementia, sensory deficits, and frailty interacting with precipitating factors of infection, medications, surgery, and metabolic derangement to determine delirium threshold.</image>

Section 3: Delirium Management

Non-pharmacological interventions form the foundation of delirium management and prevention and should be implemented for all patients with or at risk for delirium. Reorientation strategies include placing a visible clock and calendar at the bedside, providing frequent verbal reorientation to person, place, time, and situation, and ensuring that familiar objects and photographs from home are present. Sleep-wake cycle preservation involves minimizing nocturnal disruptions for vital signs and medications, reducing ambient noise and light at night, and maintaining exposure to natural light during the day. Sensory optimization requires ensuring that patients have access to their eyeglasses and hearing aids, as sensory deprivation contributes to both the development and perpetuation of delirium. Early mobilization, including sitting upright for meals, ambulating with assistance when safe, and engaging in physical therapy, counteracts the deconditioning and disorientation that accompany prolonged bed rest.

The Hospital Elder Life Program represents the most extensively studied multicomponent non-pharmacological intervention for delirium prevention and has demonstrated consistent reduction in delirium incidence. The program targets six modifiable risk factors through standardized protocols: cognitive impairment addressed through orientation and therapeutic activities, sleep deprivation addressed through non-pharmacological sleep promotion, immobility addressed through early mobilization, visual impairment addressed through vision aids and adaptive equipment, hearing impairment addressed through amplification devices and communication aids, and dehydration addressed through fluid repletion and intake monitoring. Implementation of the HELP program has been associated with a thirty-three percent reduction in delirium incidence, decreased hospital length of stay, and reduced rates of cognitive and functional decline without increasing healthcare costs.

Pharmacological management of delirium targets the symptoms of agitation, psychosis, and sleep-wake disruption that are not adequately controlled by non-pharmacological measures alone. Antipsychotic medications, particularly haloperidol, have traditionally been the most commonly used agents for delirium-related agitation and psychosis, though recent large-scale randomized controlled trials have challenged their efficacy for delirium resolution. Haloperidol is administered at low doses of 0.5 to two milligrams orally or intramuscularly, with the advantage of minimal anticholinergic effects and available parenteral formulation. Second-generation antipsychotics including quetiapine, olanzapine, and risperidone may be better tolerated in some patients and are preferred by some clinicians. Melatonin and ramelteon have shown promise in delirium prevention by supporting circadian rhythm integrity. Benzodiazepines should be avoided in delirium because they can worsen confusion and agitation, with the exception of alcohol and benzodiazepine withdrawal delirium, in which benzodiazepines are the treatment of choice.

The treatment of delirium fundamentally depends on identifying and correcting the underlying etiology, and symptomatic management without etiological investigation is inadequate. A systematic search for all contributing factors should be conducted, as delirium is frequently multifactorial. Medication review should identify and eliminate all potentially offending agents, with particular attention to anticholinergic medications, benzodiazepines, opioids, and any newly started medications. Infection should be evaluated with cultures and imaging as indicated. Metabolic derangements including electrolyte abnormalities, renal and hepatic dysfunction, and glucose excursions should be corrected. Pain, which is both a precipitant and an exacerbating factor, should be adequately treated using scheduled rather than as-needed dosing and non-opioid analgesics when possible. Constipation and urinary retention, frequently overlooked contributors, should be assessed and treated. Family members play a vital role in the management of delirium by providing familiar presence, assisting with reorientation, and serving as informants regarding the patient's baseline cognitive and functional status.

<image>Panel A: Non-pharmacological interventions showing reorientation strategies, sleep-wake cycle preservation, sensory optimization with eyeglasses and hearing aids, and early mobilization protocols for delirium management. Panel B: Hospital Elder Life Program showing six targeted risk factors, standardized intervention protocols, thirty-three percent delirium incidence reduction, and cost-neutral implementation evidence. Panel C: Pharmacological management showing haloperidol dosing, second-generation antipsychotic options, melatonin for circadian support, benzodiazepine avoidance except in withdrawal delirium, and recent trial evidence challenging antipsychotic efficacy. Panel D: Etiological treatment approach showing systematic medication review, infection evaluation, metabolic correction, pain management, constipation and urinary retention assessment, and family involvement in reorientation and baseline reporting.</image>

Section 4: Capacity Assessment

Decision-making capacity assessment is one of the most frequently requested and clinically consequential consultations in liaison psychiatry, as the determination directly impacts patient autonomy and treatment planning. The default legal presumption is that all adults possess decision-making capacity unless demonstrated otherwise, and the burden of proof lies with the clinician who concludes that capacity is absent. Capacity is decision-specific, meaning that a patient may have capacity for one decision but not another, depending on the complexity of the decision and the cognitive demands it places on the individual. Capacity is time-specific, meaning that it can fluctuate with clinical status, and a patient found to lack capacity at one point may regain it when the underlying condition improves. The assessment should be repeated when clinical circumstances change, when the patient requests reassessment, or when new treatment decisions arise.

The four components of capacity were formalized by Appelbaum and Grisso and provide a structured assessment framework. Understanding requires that the patient can comprehend the factual information relevant to the decision, including the diagnosis, the proposed treatment, the risks and benefits of the proposed treatment, and the alternatives including the option of no treatment. Appreciation requires that the patient can apply the information to their own situation, recognizing that they have the condition in question and that the treatment could potentially benefit or harm them; deficits in appreciation often result from delusional denial of illness. Reasoning requires that the patient can manipulate the information rationally to weigh the risks and benefits and reach a decision that follows logically from their stated values, even if the clinician disagrees with the conclusion. Expression of a choice requires that the patient can communicate a consistent decision, as severely disorganized thinking, fluctuating consciousness, or severe ambivalence may prevent this.

The threshold for capacity should be calibrated to the clinical stakes of the decision, a concept known as the sliding scale approach. For decisions with low risk and high benefit, such as a blood draw for routine laboratory testing, a relatively low threshold of capacity is appropriate, and simple understanding and expression of choice may suffice. For decisions with high risk and uncertain benefit, such as a major surgical procedure with significant morbidity, a higher threshold is appropriate, requiring more robust evidence of understanding, appreciation, and reasoning. When a patient with capacity makes a decision that the treatment team considers unwise or harmful, the decision must be respected, though the clinician has an obligation to ensure the patient fully understands the consequences and to explore the patient's reasoning for the decision. When capacity is found to be absent, the clinician must identify and engage a surrogate decision-maker and ensure that the patient's previously expressed wishes, if known, guide substitute decision-making.

Several clinical scenarios commonly precipitate capacity assessments in the hospital setting. Refusal of recommended treatment, particularly when the treatment is considered life-saving, is the most common trigger and requires careful assessment to distinguish an informed, autonomous decision from one driven by psychiatric impairment, cognitive deficits, or inadequate understanding. Requests to leave against medical advice require assessment of whether the patient understands the risks of premature departure and the potential consequences of interrupted treatment. Informed consent for complex surgical or medical procedures requires the patient to integrate multiple pieces of information about risks, benefits, and alternatives. Decisions regarding end-of-life care, including do-not-resuscitate orders, hospice enrollment, and withdrawal of life-sustaining treatment, carry the highest emotional and clinical stakes and demand thorough capacity evaluation. In each scenario, the consultation note should document the specific decision being evaluated, the assessment of each of the four capacity components, the overall determination, and the clinical reasoning that supports the conclusion.

<image>Panel A: Capacity assessment principles showing default presumption of capacity, burden of proof on the assessing clinician, decision-specific and time-specific nature, and reassessment triggers. Panel B: Four capacity components showing understanding of factual information, appreciation applied to one's own situation, reasoning to weigh risks and benefits, and expression of a consistent choice with assessment methods for each. Panel C: Sliding scale approach showing low threshold for low-risk high-benefit decisions, high threshold for high-risk uncertain-benefit decisions, respect for unwise but capacitated decisions, and surrogate engagement when capacity is absent. Panel D: Common capacity assessment scenarios showing treatment refusal, against medical advice discharge, surgical consent, and end-of-life decisions with documentation requirements for each component and overall determination.</image>

Section 5: Psychiatric Manifestations of Medical Conditions

Neurological conditions produce psychiatric symptoms through direct disruption of brain structures and circuits involved in mood regulation, cognition, and behavior. Stroke, particularly involving the left frontal lobe, is associated with post-stroke depression affecting approximately one-third of survivors, and the relationship is likely mediated by both the neurobiological disruption of monoaminergic circuits and the psychological response to disability. Parkinson disease produces depression in approximately forty percent of patients, anxiety in up to sixty percent, and psychosis in twenty to forty percent, with the psychiatric manifestations contributing as much to disability and reduced quality of life as the motor symptoms. Multiple sclerosis is associated with depression in up to fifty percent of patients through both immune-mediated neuroinflammatory pathways and psychosocial factors. Traumatic brain injury can produce a range of psychiatric sequelae including depression, anxiety, personality changes, impulsivity, aggression, and in some cases psychosis, with the type and severity of symptoms influenced by the location and extent of injury.

Endocrine disorders frequently present with psychiatric symptoms that may be the initial or predominant manifestation of the underlying condition. Hypothyroidism produces fatigue, cognitive slowing, depressed mood, and psychomotor retardation that can closely mimic major depressive disorder, making thyroid function testing an essential component of the depression workup. Hyperthyroidism produces anxiety, irritability, insomnia, emotional lability, and in severe cases psychosis, with thyroid storm representing a medical emergency that can include delirium. Cushing syndrome, resulting from chronic cortisol excess, produces depression in approximately fifty to eighty percent of cases, with anxiety, irritability, and cognitive impairment also common, and the psychiatric symptoms often precede recognition of the endocrine diagnosis. Addison disease with adrenal insufficiency produces fatigue, apathy, and depression. Hypercalcemia, regardless of its cause, produces psychiatric symptoms ranging from subtle cognitive impairment and irritability to depression, psychosis, and delirium, depending on the rate and magnitude of calcium elevation.

Autoimmune and infectious conditions represent an increasingly recognized category of medical illness with prominent psychiatric manifestations. Anti-NMDA receptor encephalitis typically presents in young women with psychiatric symptoms including psychosis, agitation, personality changes, and seizures that may initially be attributed to a primary psychiatric disorder, delaying the identification of this treatable autoimmune condition. Systemic lupus erythematosus produces neuropsychiatric manifestations in twenty-five to seventy-five percent of patients, including cognitive dysfunction, psychosis, mood disorders, and delirium. HIV infection affects the central nervous system directly, producing HIV-associated neurocognitive disorder, and is associated with high rates of depression and substance use. Neurosyphilis can present with virtually any psychiatric symptom and should be considered in the differential diagnosis of new-onset psychiatric symptoms, particularly in individuals with risk factors for sexually transmitted infections. Hepatitis C is associated with depression both directly through neurotropic mechanisms and through interferon-based treatment regimens that produce psychiatric side effects.

Cardiac disease and cancer represent two common medical conditions with significant psychiatric comorbidity that impacts medical outcomes. Depression occurs in approximately twenty percent of patients with coronary artery disease and is an independent risk factor for cardiac morbidity and mortality through both behavioral mechanisms, including poor adherence and reduced physical activity, and biological mechanisms including sympathetic activation, platelet dysfunction, and inflammation. Depression is present in approximately fifteen to twenty-five percent of cancer patients, with rates varying by cancer type, stage, and treatment, and is associated with poorer quality of life, reduced treatment adherence, and possibly worse survival outcomes. Accurate assessment requires distinguishing depressive symptoms from the expected emotional response to serious illness, and the Endicott criteria substitute non-somatic symptoms for the neurovegetative criteria that overlap with medical illness. Treatment of depression in the medically ill should consider drug interactions with disease-specific medications, organ-specific prescribing adjustments, and evidence for specific agents in specific medical populations.

<image>Panel A: Neurological conditions with psychiatric manifestations showing stroke and post-stroke depression prevalence, Parkinson disease comorbid depression and psychosis, MS immune-mediated depression, and TBI psychiatric sequelae by injury characteristics. Panel B: Endocrine disorders mimicking psychiatric illness showing hypothyroidism mimicking depression, hyperthyroidism producing anxiety and psychosis, Cushing syndrome depression prevalence, and hypercalcemia dose-dependent psychiatric symptoms. Panel C: Autoimmune and infectious psychiatric mimics showing anti-NMDA receptor encephalitis initial psychiatric presentation, lupus neuropsychiatric manifestations, HIV neurocognitive disorder, and neurosyphilis as the great imitator. Panel D: Cardiac and oncological comorbidity showing depression as independent cardiac mortality risk factor, cancer depression prevalence, Endicott criteria for assessment in medical illness, and treatment considerations for drug interactions and organ-specific prescribing.</image>

Section 6: Medication-Related Psychiatric Symptoms

Corticosteroids are among the most common causes of medication-induced psychiatric symptoms and produce a spectrum of disturbances that vary with dose and duration. Psychiatric effects occur in approximately five to eighteen percent of patients receiving systemic corticosteroids, with the risk increasing at higher doses. Euphoria and hypomania are common in the early days of treatment, while depression may develop with chronic use. Frank steroid psychosis, characterized by hallucinations, delusions, and disorganized behavior, can occur at any point during treatment and is more common at prednisone-equivalent doses exceeding forty milligrams daily. Insomnia and irritability are extremely common and may be the most functionally impairing symptoms. Management involves dose reduction when clinically feasible, and psychiatric symptoms typically resolve within days to weeks of corticosteroid discontinuation. Antipsychotic medication may be necessary for psychotic symptoms, and mood symptoms may require targeted treatment.

Opioids produce psychiatric effects that extend well beyond their analgesic properties and that clinicians must recognize and manage in the medically ill. Acute opioid administration can produce euphoria, sedation, and cognitive impairment, while chronic use is associated with depression, apathy, and hormonal changes including hypogonadism from hypothalamic-pituitary axis suppression. Opioid-induced delirium is common in hospitalized patients, particularly the elderly and those with pre-existing cognitive impairment, and may require opioid rotation or dose adjustment. Opioid withdrawal produces anxiety, dysphoria, irritability, insomnia, and autonomic symptoms that can complicate the management of pain and psychiatric conditions. The assessment and management of pain in patients with opioid use disorder presents particular challenges, as undertreating pain increases the risk of relapse while opioid administration raises concerns about addiction progression. Collaborative planning between psychiatry, pain management, and the primary team is essential for these patients.

Immunological and oncological therapies produce psychiatric side effects that have become increasingly important as these treatments expand. Interferon-alpha, used for hepatitis C and certain cancers, produces depression in up to fifty percent of patients, with many developing clinically significant symptoms requiring treatment or dose modification. Immune checkpoint inhibitors, a rapidly expanding class of cancer immunotherapies, can produce neuropsychiatric side effects including encephalitis, mood changes, and psychosis through immune-mediated neuroinflammation. Chemotherapy-related cognitive impairment, colloquially termed "chemo brain," affects a significant proportion of patients and manifests as difficulties with attention, memory, processing speed, and executive function. Hormonal therapies for breast and prostate cancer can produce depression, anxiety, cognitive changes, and sexual dysfunction. Awareness of these treatment-related psychiatric effects enables proactive monitoring, early intervention, and informed shared decision-making about treatment continuation.

Several other commonly prescribed medication classes can produce psychiatric symptoms that may be mistaken for primary psychiatric disorders. Beta-adrenergic blockers, particularly lipophilic agents such as propranolol, can produce depression, fatigue, vivid dreams, and cognitive slowing, though the evidence linking beta-blockers to depression has been debated. Anticholinergic medications, whether prescribed intentionally or as components of other medications with anticholinergic properties, can produce cognitive impairment, confusion, and visual hallucinations, with the cumulative anticholinergic burden increasing the risk. Fluoroquinolone antibiotics can produce anxiety, insomnia, and rarely psychosis and delirium. Isotretinoin for acne has been controversially linked to depression and suicidality, though the causal relationship remains uncertain. The CL psychiatrist should conduct a comprehensive medication review for all consultation patients, identifying all agents with potential psychiatric effects and considering medication discontinuation or substitution as a first-line intervention before attributing symptoms to a primary psychiatric disorder.

<image>Panel A: Corticosteroid psychiatric effects showing dose-dependent risk, early euphoria and hypomania, chronic depression, steroid psychosis at high doses, insomnia prevalence, and management through dose reduction and antipsychotic use. Panel B: Opioid psychiatric effects showing acute euphoria and cognitive impairment, chronic depression and hypogonadism, opioid-induced delirium in elderly, withdrawal dysphoria, and collaborative management in patients with opioid use disorder. Panel C: Immunological and oncological treatment effects showing interferon-alpha depression at fifty percent, checkpoint inhibitor neuropsychiatric effects, chemotherapy cognitive impairment, and hormonal therapy mood changes. Panel D: Other medication classes producing psychiatric symptoms including beta-blocker depression, anticholinergic cognitive impairment, fluoroquinolone anxiety, isotretinoin controversy, and medication review as first-line CL intervention.</image>

Section 7: Depression in the Medically Ill

The assessment of depression in medically ill patients is complicated by the overlap between neurovegetative symptoms of depression and symptoms attributable to the medical condition itself. Fatigue, appetite changes, weight loss, sleep disturbance, and psychomotor retardation may result from cancer, heart failure, chronic kidney disease, or other medical conditions rather than depression, producing false-positive assessments when standard diagnostic criteria are applied uncritically. The inclusive approach counts all symptoms toward the depression diagnosis regardless of their potential medical attribution and maximizes sensitivity but sacrifices specificity. The exclusive approach removes somatic symptoms from the diagnostic assessment, counting only cognitive and affective symptoms, and improves specificity but may miss some cases. The Endicott substitution approach replaces somatic criteria with non-somatic alternatives: fatigue is replaced by brooding, appetite change by depressed appearance, sleep disturbance by social withdrawal, and psychomotor change by non-reactivity, providing a balanced approach that has been validated in several medical populations.

Screening instruments adapted for medically ill populations facilitate the detection of depression in patients who may not spontaneously report mood symptoms. The Patient Health Questionnaire-2, asking about depressed mood and anhedonia, provides a rapid screen that can be integrated into routine medical care. The Hospital Anxiety and Depression Scale was specifically designed for use in medical settings and minimizes somatic items that overlap with physical illness. The single-item distress thermometer, asking patients to rate their distress on a scale from zero to ten, has been validated as a rapid screening tool in oncology settings. When screening is positive, a comprehensive clinical assessment should follow, including exploration of the patient's cognitive and affective symptoms, their understanding of and emotional response to their medical condition, their prior psychiatric history, and their current coping resources and social support.

Treatment of depression in the medically ill requires careful consideration of the medical context, drug interactions, and organ-specific prescribing. SSRIs remain the first-line treatment for most medically ill populations, with sertraline having the strongest evidence base in post-cardiac event depression and citalopram being well tolerated in many medical contexts. Duloxetine offers advantages when comorbid pain is present but must be avoided in patients with hepatic impairment. Mirtazapine may be beneficial for patients with nausea, poor appetite, and insomnia, symptoms common in medical illness, but its weight gain and sedation must be monitored. Methylphenidate at low doses provides rapid onset antidepressant effects in patients with limited life expectancy who cannot wait the weeks required for SSRI onset. Psychotherapy, particularly problem-solving therapy and behavioral activation, can be adapted for the medical setting and delivered at the bedside. Collaborative care models that integrate depression screening, stepped-care treatment, and care management within the medical team have demonstrated the strongest evidence for improving depression outcomes in the medically ill.

Specific medical conditions require tailored pharmacological approaches to depression management. In heart failure, SSRIs are preferred because they lack the cardiovascular effects of tricyclic antidepressants, and exercise-based interventions have demonstrated additional benefit. In chronic kidney disease, dose adjustments are required for renally cleared medications, and electrolyte effects of psychiatric medications must be monitored carefully. In hepatic disease, medications with hepatotoxic potential should be avoided, and agents metabolized by glucuronidation rather than oxidative pathways are preferred. In epilepsy, antidepressants with seizure-lowering potential such as bupropion must be avoided, while SSRIs are generally safe and may even raise the seizure threshold. In transplant patients, drug interactions between psychotropics and immunosuppressants require careful management, with particular attention to CYP3A4 interactions affecting calcineurin inhibitors. In oncology patients, the interaction between certain SSRIs and tamoxifen through CYP2D6 inhibition must be avoided to preserve tamoxifen's active metabolite conversion.

<image>Panel A: Depression assessment challenges in medical illness showing symptom overlap, inclusive versus exclusive versus Endicott substitution approaches with sensitivity and specificity tradeoffs for each. Panel B: Screening instruments for medically ill populations showing PHQ-2 for rapid screen, Hospital Anxiety and Depression Scale for reduced somatic overlap, and distress thermometer for oncology with follow-up comprehensive assessment pathway. Panel C: Pharmacotherapy in the medically ill showing sertraline for cardiac patients, duloxetine for pain with hepatic caution, mirtazapine for appetite and nausea, methylphenidate for limited prognosis, and collaborative care model evidence. Panel D: Disease-specific depression management showing heart failure SSRI preference, renal dose adjustments, hepatic glucuronidation preference, epilepsy bupropion avoidance, transplant CYP3A4 considerations, and oncology tamoxifen-CYP2D6 interaction.</image>

Section 8: Anxiety and Adjustment in Medical Settings

Anxiety in the medically ill ranges from normative apprehension about diagnosis and treatment to clinically significant anxiety disorders that impair coping and medical outcomes. Disease-related anxiety includes fear of disease progression, treatment side effects, pain, disability, and death, and represents an expected emotional response that may not require psychiatric diagnosis or treatment unless it is persistent, severe, or functionally impairing. Pre-existing anxiety disorders including generalized anxiety disorder, panic disorder, and PTSD may be exacerbated by the stress of medical illness, hospitalization, and treatment. Medical conditions themselves can produce anxiety through direct physiological mechanisms: hyperthyroidism, pheochromocytoma, hypoglycemia, hypoxia, cardiac arrhythmias, and pulmonary embolism all produce anxiety as a symptom, and these medical causes must be excluded before attributing anxiety to a psychiatric etiology.

Adjustment disorder is one of the most frequently diagnosed conditions in consultation-liaison psychiatry and describes emotional or behavioral symptoms developing in response to an identifiable stressor, in this case the medical illness, that are out of proportion to the severity or expected impact of the stressor. Adjustment disorder differs from normal stress reactions in the degree of distress or functional impairment, and differs from major depression or generalized anxiety disorder in not meeting the full diagnostic criteria for these conditions. The condition is specified by the predominant symptom type: with depressed mood, with anxiety, with mixed anxiety and depressed mood, with disturbance of conduct, or with mixed disturbance of emotions and conduct. Treatment emphasizes supportive psychotherapy, problem-solving approaches, and enhancement of coping skills. Pharmacotherapy may be appropriate for significant symptom burden, with short-term use of low-dose benzodiazepines or SSRIs depending on the predominant symptoms and the expected duration of the stressor.

Coping style significantly influences the patient's psychological adaptation to medical illness and predicts adjustment outcomes. Active coping styles, including problem-solving, information-seeking, and seeking social support, are generally associated with better psychological adjustment and health outcomes. Avoidant coping styles, including denial, behavioral disengagement, and substance use, are associated with poorer adjustment and may interfere with treatment adherence. However, transient denial may serve an adaptive function in the immediate aftermath of a devastating diagnosis by allowing the patient to process information gradually. The clinician should assess the patient's characteristic coping style and provide interventions that strengthen adaptive coping while gently addressing maladaptive patterns. Supportive psychotherapy in the medical setting focuses on validation, normalization of the emotional response to illness, enhancement of the patient's sense of control, and facilitation of meaningful connection with support systems and treatment providers.

Treatment non-adherence in medical settings frequently prompts psychiatric consultation and requires careful assessment of the multifactorial contributors. Cognitive barriers include misunderstanding of the medical condition or treatment, health literacy limitations, and cognitive impairment from delirium, dementia, or medication effects. Psychiatric barriers include depression-related hopelessness and amotivation, anxiety about treatment side effects, psychosis-related denial of illness, and substance use that competes with treatment engagement. Practical barriers encompass cost, transportation, complex medication regimens, and inadequate social support. Relational barriers include mistrust of the healthcare system, poor communication with providers, and experiences of discrimination or disrespect. The consultation should identify the specific barriers operating in each case and recommend targeted interventions, which may include simplifying the treatment regimen, providing patient education, addressing psychiatric symptoms, engaging social work for practical barriers, and improving the patient-provider communication.

<image>Panel A: Anxiety in the medically ill showing disease-related normative anxiety, pre-existing anxiety disorder exacerbation, and medical conditions producing anxiety through physiological mechanisms with differential diagnosis requirements. Panel B: Adjustment disorder showing diagnostic criteria with disproportionate response to identifiable stressor, differentiation from normal reactions and major psychiatric disorders, subtype specification, and treatment with supportive therapy and targeted pharmacotherapy. Panel C: Coping style assessment showing active coping associated with better outcomes, avoidant coping with poorer adjustment, transient adaptive denial, and therapeutic interventions to strengthen adaptive coping and address maladaptive patterns. Panel D: Treatment non-adherence evaluation showing cognitive, psychiatric, practical, and relational barrier categories with targeted interventions for each including regimen simplification, psychiatric treatment, social work engagement, and communication improvement.</image>

Section 9: Pain and Psychiatry

The biopsychosocial model of pain recognizes that the experience of pain involves biological, psychological, and social dimensions that interact to determine pain intensity, suffering, and disability. The biological dimension encompasses nociception, the neural processing of tissue damage signals, as well as central sensitization, in which persistent pain input produces changes in spinal cord and brain processing that amplify and perpetuate pain beyond the duration of tissue injury. The psychological dimension includes the cognitive appraisal of pain, including catastrophizing, fear-avoidance beliefs, and self-efficacy; the emotional response including anxiety, depression, and anger; and the attentional focus on pain. The social dimension encompasses the impact of pain on role functioning, relationships, and work, as well as the influence of social reinforcement patterns and cultural attitudes on pain expression and behavior. Comprehensive pain management requires addressing all three dimensions rather than focusing exclusively on biological mechanisms.

The relationship between chronic pain and psychiatric disorders is bidirectional and clinically significant. Depression occurs in approximately thirty to fifty percent of chronic pain patients, and pain is a presenting symptom in approximately sixty percent of patients with depression. Shared neurobiological mechanisms involve the serotonergic and noradrenergic systems that modulate both mood and descending pain inhibition, providing the rationale for the use of SNRIs and tricyclic antidepressants in both conditions. Anxiety disorders, particularly generalized anxiety disorder and PTSD, are common in chronic pain and contribute to pain-related disability through fear-avoidance behavior and hypervigilance. Substance use disorders, including opioid use disorder, complicate pain management and require integrated treatment approaches. Sleep disturbance is nearly universal in chronic pain and creates a vicious cycle in which poor sleep lowers the pain threshold and increased pain further disrupts sleep.

Psychiatric approaches to pain management include psychopharmacological and psychotherapeutic interventions. Antidepressants with dual serotonin-norepinephrine reuptake inhibition, including duloxetine, venlafaxine, amitriptyline, and nortriptyline, have independent analgesic effects that are distinct from their antidepressant properties and occur at lower doses and with faster onset than the antidepressant effect. Gabapentin and pregabalin are effective for neuropathic pain and may also address comorbid anxiety. Cognitive behavioral therapy for chronic pain targets catastrophizing, fear-avoidance beliefs, and behavioral deconditioning, and has demonstrated efficacy for improving pain, function, and mood. Acceptance and commitment therapy helps patients pursue valued activities despite ongoing pain by reducing the struggle against pain and increasing psychological flexibility. Mindfulness-based stress reduction develops the capacity for non-reactive awareness of pain sensations, reducing the suffering component. Multidisciplinary pain rehabilitation programs that combine medical, psychological, and physical therapy components produce the best outcomes for chronic pain with psychiatric comorbidity.

The opioid crisis has profoundly impacted the intersection of pain and psychiatry and has redefined prescribing practices and clinical responsibilities. Psychiatric comorbidity is a risk factor for the development of opioid use disorder, and individuals with depression, anxiety, and PTSD are more likely to receive opioid prescriptions, escalate to chronic use, and develop problematic patterns of use. The assessment of patients on chronic opioid therapy should include screening for opioid use disorder using tools such as the Current Opioid Misuse Measure and monitoring for behaviors suggestive of misuse including early refill requests, dose escalation, and use of multiple prescribers. Medication-assisted treatment with buprenorphine or methadone is the standard of care for opioid use disorder and should be integrated with psychiatric and pain management. For patients with co-occurring pain and opioid use disorder, buprenorphine provides both analgesic and addiction treatment effects. The CL psychiatrist plays an important role in risk assessment, treatment planning, and coordination of care for hospitalized patients with co-occurring pain and substance use disorders.

<image>Panel A: Biopsychosocial pain model showing biological nociception and central sensitization, psychological appraisal, emotion, and attention, and social role impairment, reinforcement, and cultural factors with their interactions. Panel B: Chronic pain and psychiatric comorbidity showing depression co-occurrence at thirty to fifty percent, shared serotonin-norepinephrine neurobiology, anxiety fear-avoidance contribution, substance use complications, and sleep-pain cycle. Panel C: Psychiatric pain management showing SNRI and TCA analgesic effects, gabapentin for neuropathic pain and anxiety, CBT targeting catastrophizing, ACT promoting valued action, MBSR for non-reactive awareness, and multidisciplinary rehabilitation. Panel D: Opioid crisis intersection with psychiatry showing psychiatric comorbidity as opioid use disorder risk factor, misuse screening tools, buprenorphine and methadone for medication-assisted treatment, and CL psychiatrist role in coordinated care.</image>

Section 10: Special CL Topics

Transplant psychiatry represents a specialized area of consultation-liaison practice that involves pre-transplant psychosocial evaluation, perioperative psychiatric management, and long-term post-transplant follow-up. Pre-transplant evaluation assesses the candidate's psychiatric stability, substance use history with documentation of abstinence for alcohol and substance-related liver disease, social support adequacy, adherence history, and capacity to understand and consent to the complex post-transplant regimen. Psychiatric conditions are not absolute contraindications to transplantation, but active substance use, severe untreated psychiatric illness, and inadequate social support may delay listing until these issues are addressed. Post-transplant psychiatric issues include medication-induced psychiatric symptoms from immunosuppressants including corticosteroids and calcineurin inhibitors, delirium in the perioperative period, adjustment to life with a transplanted organ, and the challenge of maintaining lifelong medication adherence. Drug interactions between psychotropics and immunosuppressants, particularly CYP3A4-mediated interactions affecting tacrolimus and cyclosporine levels, require careful pharmacological management.

Perinatal consultation-liaison psychiatry addresses the psychiatric needs of women during pregnancy and the postpartum period within the obstetric and neonatal care settings. Peripartum depression affects approximately fifteen percent of women and requires assessment that distinguishes the transient "baby blues" from clinically significant depression that impairs maternal functioning and bonding. Postpartum psychosis occurs in approximately one to two per thousand deliveries and represents a psychiatric emergency characterized by the rapid onset of hallucinations, delusions, disorganized behavior, and mood lability, often within the first two weeks after delivery, and carries a significant risk of harm to the mother and infant. The management of psychiatric medications during pregnancy involves weighing the risks of fetal medication exposure against the risks of untreated maternal psychiatric illness, which include preterm birth, low birth weight, impaired bonding, and maternal self-harm. Breastfeeding compatibility of psychiatric medications is another important consideration that requires knowledge of specific medication transfer into breast milk and potential neonatal effects.

Psycho-oncology is the subspecialty focused on the psychological, behavioral, and social aspects of cancer and addresses psychiatric issues across the cancer trajectory from diagnosis through survivorship or end-of-life care. Screening for distress is recommended by the National Comprehensive Cancer Network as a standard of care for all cancer patients, using tools such as the distress thermometer with a problem list that captures practical, family, emotional, spiritual, and physical concerns. Demoralization, a state of existential distress characterized by a sense of meaninglessness, helplessness, and loss of purpose, is distinct from clinical depression and requires existential and meaning-centered therapeutic approaches. Anticipatory grief and bereavement support for patients with advanced cancer and their families represents an important aspect of comprehensive oncological care. The interface between palliative care and psychiatry is growing, with increasing recognition that psychiatric expertise enhances the management of psychological distress, delirium, and existential suffering at the end of life.

The emergence of integrated and collaborative care models represents the evolution of consultation-liaison psychiatry beyond the traditional model of episodic consultation toward systematic population-based approaches. The Collaborative Care Model, developed at the University of Washington, integrates a psychiatric consultant, a care manager, and a primary care or medical provider to deliver measurement-based psychiatric treatment within the medical setting. The model uses a registry to track all patients with identified psychiatric conditions, systematic screening to identify new cases, stepped-care treatment protocols, and regular psychiatric case review to optimize outcomes. Evidence from over eighty randomized controlled trials demonstrates that the collaborative care model produces superior outcomes for depression, anxiety, and other psychiatric conditions compared to usual care, with sustained benefits and cost-effectiveness over time. Implementation within hospital medicine, oncology, cardiology, and primary care settings continues to expand.

<image>Panel A: Transplant psychiatry showing pre-transplant psychosocial evaluation components, substance use abstinence requirements, post-transplant medication-induced psychiatric symptoms, and CYP3A4 drug interaction management with immunosuppressants. Panel B: Perinatal CL psychiatry showing peripartum depression at fifteen percent prevalence, postpartum psychosis as emergency at one to two per thousand deliveries, medication risk-benefit during pregnancy, and breastfeeding compatibility considerations. Panel C: Psycho-oncology showing NCCN distress screening recommendation, demoralization as distinct from depression, anticipatory grief and bereavement support, and palliative care-psychiatry interface for end-of-life psychological management. Panel D: Collaborative care model showing psychiatric consultant, care manager, and primary provider integration, registry-based tracking, stepped-care protocols, and evidence from eighty-plus RCTs demonstrating superior outcomes.</image>

Summary

• Consultation-liaison psychiatry addresses the interface between psychiatric and medical illness, with delirium as the most common reason for consultation in general hospitals
• Delirium requires acute onset with fluctuating attention and is assessed using the Confusion Assessment Method, with hypoactive delirium the most frequently missed subtype
• Non-pharmacological interventions including reorientation, sleep hygiene, and early mobilization are the foundation of delirium management, with antipsychotics used selectively for agitation
• Decision-making capacity requires assessment of understanding, appreciation, reasoning, and expression of choice, with the threshold calibrated to the stakes of the decision
• Medical conditions including stroke, Parkinson disease, hypothyroidism, and anti-NMDA receptor encephalitis can present with psychiatric symptoms requiring differential diagnosis
• Medications including corticosteroids, opioids, and immunotherapies produce psychiatric side effects that must be distinguished from primary psychiatric disorders
• Depression assessment in the medically ill is complicated by symptom overlap, and the Endicott substitution criteria provide a validated alternative approach
• Adjustment disorder is among the most common CL diagnoses and is treated with supportive psychotherapy and targeted pharmacotherapy
• Chronic pain and psychiatric disorders share neurobiological mechanisms and benefit from integrated treatment with SNRIs, CBT, and multidisciplinary rehabilitation
• Collaborative care models integrate psychiatric treatment within medical settings and produce superior outcomes across more than eighty randomized controlled trials

Key Terms

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