Alterations of Dopamine D2 Receptors and Related Receptor-Interacting Proteins in Schizophrenia: The Pivotal Position of Dopamine Supersensitivity Psychosis in Treatment-Resistant Schizophrenia
INTRODUCTION This article proposes a review of atypical multicentre studies for drug-induced movement disorders (and related psychiatric symptoms) and supersensitivity psychosis. A well-conducted antipsychotic treatment consists of regular attempts to reduce the dose by finding the minimal therapeutic dose. To achieve optimal antipsychotic treatment, it is important to distinguish psychiatric symptoms associated with drug-induced movement disorder(s) (DIMD) or supersensitivity psychosis from true relapse. LITERATURE FINDINGS Persistent DIMD have been found to be a predictor of supersensitivity psychosis or tardive dyskinesia (DT). DIMD-associated psychiatric symptoms can be classified into three types: directly induced by DIMD; resulting from confounding DIMD with psychiatric symptoms; and supersensitivity symptoms associated with DIMD. Without this distinction, the beneficial effects of antipsychotics are masked by emergent DIMD psychiatric symptoms (as was confounded in the CATIE study). DISCUSSION A constant decline in the prevalence of TD (hyperkinetic, involuntary and purposeless movement disorder) has been observed since the introduction of atypical antipsychotics. The neurotoxic effects of classical antipsychotics are well documented and their discontinuation is required. However, the risk of TD still exits with atypical antipsychotics and continued surveillance of emerging cases is very important for clinicians. Moreover, a regular evaluation of DIMD and associated psychiatric symptoms is crucial. It is important to underline the fact that DIMD persists with antipsychotics, with significantly higher total PANSS scores than in patients without DIMD. CONCLUSION Supersensitivity psychosis is a drug-induced psychotic relapse (6 weeks following the decrease or withdrawal of an antipsychotic). Discontinuation syndromes can produce psychiatric symptoms (and be confounded with true relapse), but can be improved more quickly after reintroduction of treatment. Interestingly, various data suggest that lower doses of antipsychotics could prevent such symptoms. Anticonvulsants can be efficient adjuvants in the treatment of psychosis. In the United States, many patients received valproate or gabapentin treatment. These adjuvants, by antikindling effect, can facilitate minimal maintenance drug treatment and be efficient for anxiety. Resistant schizophrenia can be related to supersensitivity psychosis; gabapentin and lamotrigine are effective in this case.