# Capacity Assessment and Informed Consent

## Introduction

Capacity assessment is one of the most frequently requested psychiatric consultations in the general hospital setting. Unlike **competency**, which is a legal determination made by a court, **decisional capacity** is a clinical judgment rendered by any treating physician. Understanding the nuances of capacity evaluation is essential for every psychiatrist, as it sits at the intersection of clinical medicine, ethics, and the law.

## Defining Capacity vs. Competency

**Decisional capacity** is a clinical determination: can this patient make this specific decision at this specific time? **Competency** is a legal determination: only a judge can declare a person incompetent. All adult patients are **presumed to have capacity** until demonstrated otherwise. Capacity is **task-specific** and **time-dependent**; a patient may lack capacity for one decision but retain it for another.

## The Four-Component Model (Appelbaum and Grisso)

| Component | Definition | Assessment Method | Example of Impairment |
|-----------|-----------|-------------------|----------------------|
| Understanding | Comprehends diagnosis, treatment, alternatives, risks/benefits | Ask patient to paraphrase disclosed information | Delirium, intellectual disability, severe psychosis |
| Appreciation | Recognizes how information applies to their own situation | "How do you think this applies to you?" | Delusional denial ("I don't have cancer, it's a conspiracy") |
| Reasoning | Engages in rational process of weighing options | Explore logic of decision-making process | Disorganized thought process, severe mania |
| Expressing a Choice | Communicates a stable, consistent decision | Note consistency over time | Mutism, catatonia, rapidly fluctuating states |

### Understanding

The patient must comprehend the disclosed information about diagnosis, proposed treatment, alternatives, and risks/benefits. Assessed by asking the patient to paraphrase the information in their own words.

### Appreciation

The patient must appreciate how the information applies to their own situation. Distinguishes from mere factual understanding; tests for **pathological denial** or delusional distortion.

### Reasoning

The patient must engage in a rational process of weighing options. Clinicians assess the logical consistency of the patient's thought process, not the outcome of the decision.

### Expressing a Choice

The patient must be able to communicate a stable and consistent decision. Fluctuating or contradictory choices may suggest impaired capacity.

![Diagram illustrating the four components of decisional capacity: understanding, appreciation, reasoning, and expressing a choice](/images/psychiatry/capacity-four-components.png)

## The Informed Consent Process

**Disclosure**: providing information about the nature of the intervention, risks, benefits, and alternatives. **Voluntariness**: the decision must be free of coercion, manipulation, or undue influence. **Capacity**: the patient must possess decisional capacity. Informed consent is a **process**, not merely a signed form. Documentation should reflect the discussion, not just the patient's signature.

### Exceptions to Informed Consent

**Emergency situations** where delay would endanger life or health. **Therapeutic privilege** (rarely invoked, ethically controversial) **Waiver**: the patient voluntarily relinquishes the right to be informed. **Public health mandates** (e.g., involuntary quarantine)

## Clinical Approach to Capacity Evaluation

### When to Assess

Patient refuses recommended treatment. Patient consents to a high-risk procedure with questionable understanding. Acute change in mental status. Known psychiatric or neurological illness affecting cognition.

### The Assessment Interview

Review the medical record and speak with the treatment team before seeing the patient. Use open-ended questions: "Tell me in your own words what the doctors have told you about your condition". Assess for psychiatric conditions that may impair capacity: **delirium, dementia, psychosis, severe depression**. Use the **MacArthur Competence Assessment Tool for Treatment (MacCAT-T)** as a structured aid when needed.

![Flowchart showing the clinical algorithm for capacity evaluation and next steps](/images/psychiatry/capacity-assessment-algorithm.png)

## Enhancing Capacity

Treat reversible conditions (delirium, pain, medication effects) Provide information in simplified language, using visual aids. Reassess after interventions; capacity can improve. Involve interpreters for language barriers. Time the assessment when the patient is at their cognitive best.

## When a Patient Lacks Capacity

Identify a **surrogate decision-maker** (healthcare proxy, next of kin per state hierarchy) The surrogate should use **substituted judgment** (what the patient would have wanted) when prior preferences are known. If prior wishes are unknown, the **best interest standard** applies. Document the rationale clearly and involve the ethics committee for complex cases.

## Special Considerations

**Against Medical Advice (AMA) discharges**: patients leaving AMA must also have capacity to make that decision. **Capacity in research settings**: higher threshold of understanding may be required. **Adolescents and emancipated minors**: state-specific rules govern consent. **Fluctuating capacity**: common in delirium; serial assessments are necessary.

![Table comparing capacity thresholds based on risk-benefit ratio of the proposed intervention](/images/psychiatry/sliding-scale-capacity.png)

## Key Clinical Pearls

A patient's decision that seems unwise does not equate to incapacity; the quality of the decision-making process matters, not the decision itself. The threshold for capacity should be proportional to the stakes: the **sliding scale model** holds that riskier decisions with less clear benefit demand a higher standard of capacity. Always document the specific questions asked, the patient's responses, and your clinical reasoning. Capacity assessments protect patient autonomy; they are not tools for overriding patient preferences.

## References

1. Appelbaum PS. Assessment of patients' competence to consent to treatment. *N Engl J Med*. 2007;357(18):1834-1840.
2. Grisso T, Appelbaum PS. *Assessing Competence to Consent to Treatment: A Guide for Physicians and Other Health Professionals*. Oxford University Press; 1998.
3. Sturman ED. The capacity to consent to treatment and research: a review of standardized assessment tools. *Clin Psychol Rev*. 2005;25(7):954-974.
4. American Psychiatric Association. *The APA Practice Guidelines for the Psychiatric Evaluation of Adults*. 3rd ed. 2016.