Does clozapine cause or worsen obsessive compulsive symptoms? An analysis and literature review

Clozapine is the most effective antipsychotic in treatment-resistant schizophrenia but its use portends with a high burden of adverse reactions. One adverse event reported both in case reports and cross-sectional surveys is the emergence or worsening of obsessive compulsive symptoms (OCS).

This study presents a retrospective review of a UK cohort of clozapine-treated individuals with the aim to further investigate the complex relationship between clozapine and OCS.

An extensive review of the medical records of 49 patients receiving clozapine in the Southampton area was undertaken. We searched for a diagnosis of obsessive compulsive disorder, signs or symptoms of obsessive compulsive disorder or the prescribing of selected antidepressants the year before clozapine initiation and the year after.

Fifteen patients (31%) had reports of OCS during the 2-year data collection period. Twelve patients (24%) had OCS before clozapine initiation while only 7 (14%) had symptoms after clozapine was initiated. De novo OCS were reported in three (6%) cases after 5-9 months of clozapine treatment.

As with previous studies it was not possible to establish a definitive link between clozapine and OCS. Clinicians should be mindful of the common comorbidity of OCS and schizophrenia and the possible increased risk incurred when starting clozapine.