Background: This study aimed to assess if decisional capacity and the four decision-making abilities related to decisions concerning medication management were impaired among community-dwelling Chinese older persons in Hong Kong with amnestic mild cognitive impairment (MCI) and mild Alzheimer's disease (AD), as compared with cognitively normal older adults.

Methods: Two hundred and ninety-one Chinese community-dwelling older adults were recruited. The four decision-making abilities and decisional capacity were assessed by using the Chinese version of the Assessment of Capacity for Everyday Decision-Making (ACED) and independent clinician ratings based on the definition in the UK Mental Capacity Act 2005, respectively.

Results: Ninety-nine participants (34%) were diagnosed with MCI and ninety-five (33%) with mild AD. Although almost all (96%) of the participants in the MCI group were found to be mentally competent to make decisions on medication management in clinician ratings, their decision-making abilities as measured by the ACED were significantly lower than those of the cognitively normal controls.

Conclusions: Results from this study suggest that abilities related to decisions on medication management are impaired before the clinical diagnosis of dementia is made. Use of specific and structured assessment of the relevant decisional abilities may enhance clinical judgment.