Correlates of treatment-related decision-making capacity among middle-aged and older patients with schizophrenia.

BACKGROUND: Antipsychotic medications constitute the backbone of treatment for schizophrenia. Current guidelines require clinicians to obtain patients' informed consent for treatment, but few empirical studies of the capacity of patients with schizophrenia for meaningful consent in this context exist. This issue may be particularly relevant for middle-aged and older patients, as the cognitive changes associated with normal aging may have an adverse impact on decision-making processes. We examined the range, stability, and correlates of treatment-related decisional capacity in this patient population.
METHODS: Participants included 59 middle-aged and older patients with schizophrenia or schizoaffective disorder and 38 normal comparison subjects. Baseline measures included the MacArthur Competence Assessment Tool for Treatment (MacCAT-T), psychopathology rating scales, and the Mattis Dementia Rating Scale. Patients also completed a neuropsychological test battery. The MacCAT-T was readministered to patients at a 1-month follow-up.
RESULTS: Relative to the comparison subjects, the patients had worse understanding of disclosed material; however, a wide range of performance was observed among patients. Variability in MacCAT-T performance was not predicted by demographic characteristics; there were no significant correlations between psychopathology ratings and MacCAT-T scores. Cognitive test scores were often significant correlates of capacity, particularly in terms of understanding and reasoning. The MacCAT-T scores were stable during the 1-month follow-up.
CONCLUSIONS: Overall, middle-aged and older outpatients with schizophrenia had worse understanding of disclosed information than did normal comparison subjects, but such group comparisons obscure remarkable heterogeneity among patients. Differences in capacity appeared more related to cognitive functions than to severity of psychopathology. Such information about barriers to capacity may help in developing more effective methods of providing informed consent.