Paradoxical severe agitation induced by add-on high-doses quetiapine in schizo-affective disorder

We report the case of a 35-year-old patient suffering from schizo-affective disorder since the age of 19 years, treated by a combination of first-generation antipsychotics, zuclopenthixol (100 mg/day) and lithium (1200 mg/day) (serum lithium=0.85 mEq/l). This patient had no associated personality disorder (particularly no antisocial disorder) and no substance abuse disorder. Within the 48 h following the gradual introduction of quetiapine (up to 600 mg/day), the patient presented severe agitation without an environmental explanation, contrasting with the absence of a history of aggressiveness or personality disorder. The diagnoses of manic shift and akathisia were dismissed. The withdrawal and the gradual reintroduction of quetiapine 2 weeks later, which led to another severe agitation, enabled us to attribute the agitation specifically to quetiapine.