Schizophrenia is a heterogeneous disease involving genetic and environmental factors. The frequency of structural brain abnormalities or physical anomalies supports a neurodevelopmental etiology, especially in early onset schizophrenia. Brain-Derived-Neurotrophic-Factor (BDNF) is involved in the neurodevelopment of dopaminergic (DA)-related systems and interacts with the meso-limbic DA systems, involved in the therapeutic response to antipsychotic drugs and substance abuse. In addition, BDNF promotes and maintains dopamine D3 receptor (DRD3) expression. In a French Caucasian population, we found no statistical difference in allele or genotype distribution of the BDNF gene dinucleotide repeat polymorphism (166-174 bp) between the whole group of schizophrenic patients and controls. By contrast, an excess of the 172-176 bp alleles was found in patients with late onset, in neuroleptic-responding patients and in non-substance-abusing patients. BDNF gene variants thus appear to be associated with developmental features of schizophrenia. In addition, this association with good treatment responding was independent from the association found with the DRD3 Ball gene polymorphism in the same population. These results suggest an independent contribution of each gene to a treatment-sensitive form of schizophrenia.

Antipsychotic polypharmacy and high doses have been associated with poorer outcome, longer hospital stays, and increased side effects. The present naturalistic study assessed the cognitive effects of antipsychotics in 56 patients with a diagnosis of schizophrenia or schizoaffective disorder, using the Brief Assessment of Cognition in Schizophrenia (BACS). Antipsychotic daily dose (ADD) was expressed as mg risperidone equivalents/day (RIS eq), using a model based on drug doses from the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) study for second generation antipsychotics (SGA) and chlorpromazine equivalents for first generation antipsychotics (FGA), with a 1/1 equivalence between haloperidol and risperidone. Increasing age was associated with polypharmacy, FGA prescription and decreasing BACS score. FGA prescription, in turn, predicted a poorer cognitive functioning, independently of age, PANSS subscores and ADD. ADD was associated with decreasing cognitive scores, an effect that remained significant after controlling for age, PANSS or polypharmacy. The detrimental cognitive effects of polypharmacy, in turn, appeared to be mediated by ADD. Different methods of data fitting suggested that ADD above 5-6 mg RIS eq/day were associated with lower BACS scores. Overall, these results show that increasing antipsychotic daily dose is associated with poorer cognitive functioning at doses lower than previously thought, independently of the number of antipsychotic drugs.

Energy homeostasis is achieved by the integration of peripheral metabolic signals by the neural circuits involving specific hypothalamic nuclei and brain stem regions. These neural circuits mediate many of the effects of the adipocyte-derived hormone leptin and gut-derived hormone ghrelin. The former is strongly anorexigenic while the latter is the only orexigenic agent active when administered by a peripheral route. Abnormal regulation of these 2 antagonistic regulatory peptides in patients with schizophrenia could play a role in the impairment in the regulation of food intake and energy balance. This bibliographical analysis aims to compare 27 prospective and cross-sectional studies published on circulating leptin and ghrelin levels during acute and chronic administration of antipsychotics treatment, especially atypical ones. Fasting morning leptin levels of schizophrenic patients increase rapidly in the first 2 weeks after atypical antipsychotic (AAP) treatment (mostly olanzapine and clozapine) and remain somehow elevated after that period up to several months. On the contrary, conventional antipsychotics (such as haloperidol) do not interfere with leptin levels. In contrast to leptin, fasting morning ghrelin levels decrease during the first few weeks after the beginning of AAPs treatment while they increase in the longer run. Surprisingly, body weight gain and correlations between the variation of these 2 peptides and adiposity and metabolism-related parameters such as the body mass index and abdominal perimeter were not systematically considered. Finally, an objective evaluation of feeding behavior during antipsychotic treatment remains to be determined.