The Impact of Anticholinergic Burden on Functional Capacity in Persons With Schizophrenia Across the Adult Life Span

Abstract

Anticholinergic burden (ACB) from medications impairs cognition in schizophrenia. Cognition is a predictor of functional capacity; however, little is known about ACB effect on functional capacity in this population. This study assesses the relationship between ACB and functional capacity across the life span in individuals with schizophrenia after controlling for ACB effect on cognition. A cross-sectional analysis was performed with data collected from 6 academic tertiary health centers. Two hundred and twenty-three community-dwelling participants with schizophrenia or schizoaffective disorder were included in this study. Main variables were ACB, antipsychotic olanzapine equivalents, functional capacity, cognition, and negative symptoms. Simultaneous linear regression analyses were performed to assess the association between ACB, functional capacity, and cognition and then between ACB and cognition. A mediation analysis was then performed to examine whether cognition mediated ACB effect on functional capacity if there was an association between ACB and cognition. Mean age of participants was 49.0 years (SD = 13.1, range 19-79), and 63.7% of participants had severe ACB, ie, a total score of 3 or above. Regression analyses revealed that ACB, age, education, and cognition independently predicted functional capacity and that ACB predicted cognition among those aged 55 years and older. Mediation analysis showed that cognition did partially mediate the effect of ACB on functional capacity in this older cohort. In conclusion, people with schizophrenia are exposed to severe ACB that can have a direct negative impact on functional capacity after controlling for its impact on cognition. Reducing ACB could improve functional capacity and potentially real-world function in schizophrenia.

Keywords: aging; anticholinergic burden/cognition/functional capacity; schizophrenia.

Fig. 1.

Anticholinergic burden, cognition, and functional capacity among older adults with schizophrenia. This figure illustrates the model for global cognition as mediating the effect of anticholinergic burden (ACB) on functional capacity among adults with schizophrenia, after controlling for age. The model shows that ACB has a total direct negative effect on functional capacity (c-path), a direct effect on cognition (a-path), and a significant direct effect on functional capacity after controlling for cognition as the mediator (c’-path). Cognition has also a direct effect on functional capacity (b-path), and it partially mediated the effect of ACB on functional capacity (ab = −0.15 BCa CI [−0.25, −0.038]) with an indirect effect accounting for roughly 41% of the total effect (P_M = .41).