Declining medical decision-making capacity in mild AD: a two-year longitudinal study

Area of Science:

• Neurology
• Geriatrics
• Medical Ethics

Background:

• Assessing medical decision-making capacity (MDC) is crucial for patient autonomy, especially in neurodegenerative conditions.
• Alzheimer's disease (AD) progressively impacts cognitive functions essential for informed consent.
• Longitudinal data on MDC decline in mild AD is limited.

Purpose of the Study:

• To longitudinally evaluate medical decision-making capacity (MDC) in individuals with mild Alzheimer's disease (AD) over two years.
• To compare MDC performance between healthy older adults and mild AD patients.
• To identify specific cognitive standards of capacity that decline over time in mild AD.

Main Methods:

• A two-year longitudinal study involving 15 healthy older adults and 20 patients with mild AD.
• Utilized the Capacity to Consent to Treatment Instrument (CCTI) to assess five standards of MDC: S1 (choice), S2 (reasonable choice), S3 (appreciation), S4 (reasoning), and S5 (understanding).
• Categorized capacity outcomes as capable, marginally capable, or incapable based on control group performance benchmarks.

Main Results:

• At baseline, mild AD patients performed significantly below controls on complex capacity standards (S3, S4, S5) but equivalently on simple standards (S1, S2).
• No significant decline was observed in the mild AD group at the one-year follow-up.
• By the two-year follow-up, mild AD patients showed significant declines in complex standards (S3, S4, S5) and a trend in S1, with increased rates of marginal/incapable outcomes across four standards (S1, S3, S4, S5).

Conclusions:

• Mild AD patients exhibit impaired medical decision-making capacity (MDC) at baseline, particularly in complex cognitive abilities.
• Significant additional decline in complex consent abilities (appreciation, reasoning, understanding) occurs over a two-year period in mild AD.
• Emerging impairment in evidencing choice (S1) and overall increases in marginal/incapable capacity outcomes highlight the need for early and regular MDC monitoring in mild AD.