RESUMO
Antipsychotic medication non-adherence is a complex and multifaceted problem that may hinder recovery in psychosis-spectrum disorders. Therefore, it warrants an early and comprehensive assessment. Current self-report measures focus entirely on behavioral and attitudinal barriers to adherence, failing to provide insight about key psychosocial drivers such as shame and stigma that may also account for non-adherence. This study's main goals were to develop a brief scale for measuring antipsychotic (non)-adherence and associated intra and interpersonal barriers (Antipsychotic Medication Beliefs and Attitudes Scale - AMBAS), and explore its psychometric properties. One hundred and seventy participants with a psychosis-spectrum disorder were recruited and filled in a battery of self-report measures. Exploratory factor analysis supported a two-factor solution, with one factor tapping the influence of different barriers to medication adherence and other factor encompassing perceived positive effects of medication. The scale presented good reliability and convergent validity as evidenced by significant moderate associations with the Medication Adherence Rating Scale. Although in need for further study, AMBAS seems a valid and reliable measure to assess antipsychotic (non)-adherence and underlying behavioral and psychosocial drivers. With replication, AMBAS might be a useful measure that could be used in different clinical and research settings.