Relationship Between Cognitive Functions and Decision-Making Capacity in Older Institutionalized Patients with Schizophrenia: A Preliminary Study.

Background: Decision-making capacity for patients with psychiatric disorders is an important and controversial issue in clinical care settings. The aim of this study was to (1) evaluate the level of decision-making capacity of older institutionalized patients suffering from schizophrenia and (2) determine whether their diminished capacity is associated with specific aspects of cognitive impairment. Methods: Using a cross-sectional design, we recruited 48 older institutionalized patients (mean age ± standard deviation: 60.0 ± 14.0 years) who were diagnosed with schizophrenia. Participants underwent the assessments by the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) and the Japanese version of the Brief Assessment of Cognition in Schizophrenia (Japanese-BACS). Results: The understanding summary scores of the MacCAT were found to have a significant positive correlation with the attention and verbal fluency subscale scores of the Japanese-BACS and negative correlations with age and duration of illness. In addition, the appreciation and reasoning summary scores had a significant negative correlation with age. In a linear regression model with a stepwise selection procedure, age, sex, and verbal fluency subscale scores were associated with understanding summary scores. Conclusion: The generally poor cognitive performance of inpatients with chronic schizophrenia indicated that the informed consent process for their treatment might pressure these patients on the basis of cognitive demands. It is necessary for psychiatrists to assess individual decision-making capacity and to increase their patients' involvement in the treatment process.