Development of psychosis in patients with epilepsy treated with lamotrigine: report of six cases and review of the literature.

Lamotrigine (LTG) is a generally well-tolerated antiepileptic drug (AED) with broad-spectrum efficacy in several forms of partial and generalized epilepsy and is also licensed for use in bipolar disorder in several countries. We describe six patients who developed a psychotic disorder--in most, but not all, cases schizophrenia-like in character--under treatment with LTG, within a group of about 1400 patients treated with this drug in our center. This indicates that psychosis is a rare adverse event under LTG treatment. On the background of available drug serum levels, we suggest, in particular, an intrinsic or toxic psychotogenic effect of LTG. Possible risk factors seem to be psychiatric comorbidity and temporal lobe pathology. The described phenomenon is discussed within the context of possible psychotogenic effects of other AEDs.