Methylphenidate for psychosis and aggression in a patient comorbid with ADHD - A case report.

Attention-deficit/hyperactivity disorder (ADHD) may persist into adulthood in a substantial proportion of affected youth, with rates differing between 15 (persistence of full syndrome) and 65% (partial remission) (Faraone et al. 2005). There is ample evidence that patients suffering from ADHD carry a heightened risk for other psychiatric disorders. Adults with ADHD show high rates of comorbidity with affective and anxiety disorders, antisocial personality disorder and substance abuse disorders (Barkley & Brown 2008, Kessler et al. 2006). Though these reports lack data on psychosis, this comorbidity was in fact reported independent of psychotic symptoms induced by treatment with stimulants. In children and youth with ADHD, comorbidity with psychosis was found in 5% (Stahlberg et al. 2004) and a retrospective study in adult patients with psychosis revealed a history of ADHD in childhood in 17% (Peralta et al. 2010). Given such comorbidity the simultaneous treatment of both conditions is difficult, since the main therapeutic drugs for the two disorders – antipsychotics for psychosis and stimulants (amphetamines and methylphenidate) for ADHD – have opposing effects on the dopamine metabolism. Stimulants are known to frequently induce psychosis in recreational use (Darke et al. 2008) and were found to increase risk by an odds ratio of 11 (McKetin et al. 2006). Single doses of stimulants in experimental studies led to an increase of positive symptoms in 51% of symptomatic schizophrenic patients, 28% of remitted patients and 10% of healthy controls (McKetin et al. 2006). Stimulants serve as a model for psychosis in animal studies (Featherstone et al. 2007) and the reaction to a test dose of amphetamine has been used as predictor for schizophrenic relapse (Lieberman et al. 1987). During therapeutic use of stimulants in children psychotic states have occurred in 0.25% of patients (Ross 2006) or 1.48 cases per 100 patient-years (Mosholder et al. 2009). Antipsychotics on the other hand block effects of stimulants and are used for treatment of amphetamineinduced psychosis (Shoptaw et al. 2009). While caring for a patient with comorbidity of ADHS and psychosis we were not able to find guidelines or treatment recommendations issued by a major society concerning state of the art treatment of such a case.