Residency · Residency · Internal Medicine

Cognitive Impairment and Dementia Screening

Introduction

Cognitive impairment ranges from mild cognitive impairment (MCI) to overt dementia and affects an estimated 10-15% of adults over age 65. Early detection enables advance care planning, medication optimization, safety interventions, and caregiver support. Internists play a central role in screening, initial workup, and ongoing management.

Definitions and Classification

• Mild Cognitive Impairment (MCI): objective cognitive decline without significant functional impairment; approximately 10-15% progress to dementia annually
• Dementia: acquired cognitive decline in one or more domains sufficient to impair independent functioning
• Major subtypes: Alzheimer disease (60-80%), vascular dementia (15-20%), Lewy body dementia, frontotemporal dementia
• Delirium must be distinguished from dementia; delirium is acute, fluctuating, and often reversible

When to Screen

• Medicare Annual Wellness Visit includes a required cognitive assessment
• Screen when patient, family, or staff report memory concerns, confusion, or behavioral changes
• Assess cognition before major medical decisions or surgery in older adults
• Hospitalized patients with delirium should be reassessed for baseline cognitive impairment after resolution
• Routine screening in asymptomatic populations remains controversial (USPSTF: insufficient evidence)

Screening and Assessment Tools

Brief Screening Instruments

• Mini-Cog: 3-item recall + clock drawing; takes 3 minutes; excellent for initial screening
• Montreal Cognitive Assessment (MoCA): 30-point test; sensitive for MCI; score < 26 is abnormal
• Mini-Mental State Examination (MMSE): 30-point test; less sensitive for early impairment; score < 24 suggests dementia
• Saint Louis University Mental Status (SLUMS): 30-point test; better sensitivity than MMSE for MCI

Functional Assessment

• Activities of Daily Living (ADLs): bathing, dressing, toileting, transferring, eating
• Instrumental Activities of Daily Living (IADLs): finances, medications, transportation, cooking, shopping
• Functional impairment in IADLs often precedes ADL decline and is key to distinguishing MCI from dementia

Diagnostic Workup

Reversible Causes to Exclude

• Medications: anticholinergics, benzodiazepines, opioids, antihistamines
• Metabolic: hypothyroidism, vitamin B12 deficiency, folate deficiency, hepatic encephalopathy
• Infections: urinary tract infection, HIV, syphilis (in appropriate populations)
• Structural: normal pressure hydrocephalus (triad: gait apraxia, urinary incontinence, dementia), subdural hematoma
• Psychiatric: depression ("pseudodementia"), severe anxiety

Standard Laboratory Workup

• TSH, vitamin B12, comprehensive metabolic panel
• Consider HIV, RPR, folate based on clinical context
• Urinalysis to exclude UTI as contributing factor in acute presentations

Neuroimaging

• Non-contrast CT or MRI of the brain: recommended to exclude structural lesions
• MRI preferred for evaluating hippocampal atrophy, white matter disease, and vascular changes
• Amyloid PET imaging and CSF biomarkers (A-beta 42, phospho-tau) are increasingly used but typically reserved for specialist evaluation

Pharmacologic Management

Alzheimer Disease

• Cholinesterase inhibitors (donepezil, rivastigmine, galantamine): modest symptomatic benefit in mild-moderate disease
• Memantine: NMDA receptor antagonist for moderate-severe Alzheimer disease; may be combined with cholinesterase inhibitors
• Anti-amyloid therapies (lecanemab, donanemab): disease-modifying agents for early-stage Alzheimer disease with confirmed amyloid pathology; require ARIA monitoring with MRI
• Reassess benefit periodically; consider deprescribing in advanced disease

Behavioral and Psychological Symptoms of Dementia (BPSD)

• Non-pharmacologic interventions first: structured routines, music therapy, caregiver education, environmental modification
• Antipsychotics (risperidone, quetiapine): reserved for severe agitation or psychosis unresponsive to non-pharmacologic measures; carry FDA black box warning for increased mortality
• SSRIs (citalopram, sertraline): may help with agitation and depression
• Avoid benzodiazepines and anticholinergics

Non-Pharmacologic Management and Caregiver Support

• Advance care planning: discuss goals of care, health care proxy, and living will early
• Driving assessment: critical safety concern; refer for formal evaluation when indicated
• Caregiver burden: screen for depression and provide resources for respite care and support groups
• Safety evaluation: home safety assessment, medication management, wandering prevention
• Referral to social work, geriatrics, and community resources

Key Clinical Pearls

• The Mini-Cog is a rapid, validated screening tool suitable for busy clinical settings.
• Always exclude reversible causes of cognitive impairment including medications, metabolic derangements, and depression.
• Functional assessment (ADLs/IADLs) is essential to distinguish MCI from dementia.
• Non-pharmacologic strategies should be the first-line approach for behavioral symptoms of dementia.
• Early advance care planning and caregiver support are as important as pharmacotherapy.

References

1. Livingston G, Huntley J, Sommerlad A, et al. Dementia Prevention, Intervention, and Care: 2020 Report of the Lancet Commission. The Lancet. 2020;396(10248):413-446.
2. Nasreddine ZS, Phillips NA, Bedirian V, et al. The Montreal Cognitive Assessment, MoCA: A Brief Screening Tool for Mild Cognitive Impairment. Journal of the American Geriatrics Society. 2005;53(4):695-699.
3. Petersen RC, Lopez O, Armstrong MJ, et al. Practice Guideline Update: Mild Cognitive Impairment. Neurology. 2018;90(3):126-135.
4. van Dyck CH, Swanson CJ, Aisen P, et al. Lecanemab in Early Alzheimer's Disease. New England Journal of Medicine. 2023;388(1):9-21.

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