Psychotropic effects of COX-2 inhibitors--a possible new approach for the treatment of psychiatric disorders.

Cyclooxygenase-2 (COX-2)--constitutively expressed in the CNS--is suggested to have an important functional role in the CNS. COX-2 interacts with neurotransmitters such as acetylcholine, serotonin, and glutamate, but is also involved in the regulation of immune system and in inflammation in the central nervous system (CNS) via effects of prostaglandins, in particular prostaglandin E (2). Recently, a role for the new generation of selective COX-2 inhibitors in the treatment of psychiatric disorders is discussed. Until now, COX-2 inhibitors have failed to show therapeutic effects in Alzheimer's disease, but studies from basic research point to a possible effect on cognition. A clinical effect of the COX-2 inhibitor celecoxib on cognition was observed in schizophrenic patients. The therapeutic effect of celecoxib add-on treatment to the atypical antipsychotic risperidone, however, is not restricted to cognition. A general effect on symptoms of schizophrenia was observed, which supports the view that an immunological/inflammatory process is involved in the pathogenesis of schizophrenia. In depression, however, signs of inflammation have been described since many years. Although results of clinical studies with COX-2 inhibitors in depression are still lacking, clinical improvement of a depressive syndrome has been observed in patients, who have been treated with rofecoxib due to other indications. These preliminary clinical data are encouraging for therapeutic effects of the selective COX-2 inhibitors in psychiatric disorders, although these effects have to be confirmed in bigger clinical studies.