Capacity to make treatment decisions in Chinese older persons with very mild dementia and mild Alzheimer disease.

Objectives: This study aims at assessing mental competence in Chinese patients with mild and very mild dementia with a semistructured assessment method and the impact of repeated presentations of information on patients' mental competence.

Design: Subjects with mild and very mild dementia were compared with cognitively intact subjects.

Setting: Chinese subjects were recruited from local social centers and residential hostels for the elderly in Hong Kong.

Participants: Sixty-six Chinese community-dwelling older adults (aged from 65 to 87 years) were recruited.

Measurements: Clinical diagnosis was made by experienced geriatric psychiatrists. Subjects were assessed with the Mini-Mental State Examination and the Clinical Dementia Rating (CDR). Mental capacity to consent to treatment was assessed by using the Chinese version of the MacArthur Competence Assessment Tool-Treatment (MacCAT-T) and independent clinician ratings based on the definition in the Mental Capacity Act 2005 of the United Kingdom.

Results: Thirty-three (50%) participants were diagnosed with very mild or mild dementia (CDR = 0.5 or 1). In this group, 15 (45.5%) subjects were rated as mentally incompetent in clinician ratings. In the assessment of interrater reliability, the intraclass correlation coefficient of MacCAT-T summary scores among three raters ranged from 0.64 to 0.83. The MacCAT-T summary scores correlated significantly with clinician ratings, years of education, Mini-Mental State Examination score, and CDR. In contrast to the nonimpaired group, repeated presentation of information did not significantly improve capacity in the demented group.

Conclusion: Results from this study suggest that even patients with very mild dementia in this population can show substantial deficits in decision-making capacity, and that improved capacity is not likely to result from repeated disclosure of information.