Internalized stigma and medication adherence in schizophrenia: effects on treatment attitudes and adherence behavior

Medication adherence in schizophrenia involves psychological, cognitive, and behavioral processes that extend beyond medication-taking itself. Although internalized stigma has been associated with poorer treatment engagement, the mechanisms linking stigma to objectively verified adherence behavior remain unclear. This study examined whether attitudes toward medication mediate the relationship between internalized stigma and behavioral medication adherence in schizophrenia. A longitudinal observational study was conducted with 125 adults receiving outpatient psychiatric care in Arica, Chile. Study activities, including baseline assessments and ascertainment of the subsequent 12-month adherence periods, took place between December 2020 and December 2022. Participants entered the study on a rolling basis, and each participant’s adherence observation period was individually anchored to the baseline assessment. Internalized stigma and attitudes toward medication were assessed at baseline using the Internalized Stigma of Mental Illness Scale (ISMI-29) and the Drug Attitude Inventory (DAI-10), respectively. Behavioral medication adherence was subsequently evaluated over an individual 12-month observation period following baseline and was classified through retrospective review of pharmacy dispensing records, clinical and nursing documentation, and long-acting injectable administration records, when applicable. Internalized stigma was significantly associated with less favorable attitudes toward medication, and attitudes toward medication were significantly associated with subsequent behavioral adherence. Internalized stigma was not directly associated with adherence behavior but showed a significant indirect association through treatment attitudes. The primary model explained a modest proportion of variance in behavioral adherence. The findings were consistent with a theoretically specified indirect association between internalized stigma and subsequent behavioral medication adherence through attitudes toward medication. These results support considering adherence in schizophrenia as a multifactorial behavioral outcome associated with psychological and cognitive factors. Internalized stigma and treatment-related attitudes may therefore be relevant to recovery-oriented assessment and care, although the observational findings do not establish that modifying these factors will improve adherence.