Medication nonadherence in older people with serious mental illness: prevalence and correlates.

Medication nonadherence in people with schizophrenia and other serious mental illnesses (SMI) is multidetermined and has been consistently associated with relapse and rehospitalization, but little is known about the prevalence and correlates of nonadherence in older people with SMI. This study evaluated the interrelationships between different measures of medication adherence (including pill counts, self-report, informant report, and attitudes toward medications), and their associations with demographic characteristics, and clinical, functional, skill, and cognitive measures in a group of 72 older people with SMI living in the community. Pill counts of adherence to psychotropic medications were highly correlated with pill counts for nonpsychiatric medications. However, pill counts were weakly correlated with self-report and informant ratings, which tended to overestimate adherence. Lower medication adherence was associated with: mood disorder (compared to schizophrenia), lack of supervision, fewer prescription medications, less insight, more severe negative symptoms, and worse community functioning. Among individuals with little or no supervision of their medications, higher adherence was related to better performance on the Medication Management Administration Assessment (MMAA) role-play, which was highly correlated with several domains of cognitive functioning, suggesting that the MMAA may be a more ecologically valid measure of cognitive functioning related to medication adherence. This study highlights the importance of using multiple measures for the assessment of medication adherence in older people with SMI, including pill counts, and suggests that interventions are needed to improve adherence in this population.