Comparative analysis of anticholinergic burden scales to explain constipation in schizophrenia spectrum disorders: results from the FACE-SZ cohort

Constipation is a common and often overlooked adverse effect in individuals with schizophrenia spectrum disorders, particularly in relation to psychotropic medications with anticholinergic properties. This side effect can substantially impair quality of life, reduce medication adherence, and, in severe cases, lead to serious medical complications. Anticholinergic burden reflects the cumulative effects of such medications, but numerous anticholinergic burden scales exist, and their clinical relevance for digestive outcomes remains uncertain. This study aims to compare multiple anticholinergic burden scales to determine which measures are most strongly associated with constipation in adults with schizophrenia. Using baseline data from the FACE-SZ cohort, we will examine whether higher anticholinergic burden is independently associated with constipation and whether some scales outperform others in explaining this risk. Secondary objectives include assessing the role of clozapine exposure and exploring the associations between constipation, medication adherence, and quality of life. By identifying the most clinically informative measures of anticholinergic burden, this study seeks to improve risk stratification and support safer, more individualized psychotropic treatment strategies in schizophrenia.