ABSTRACT
Objective: Cognitive impairment is a core feature of schizophrenia, related to dopaminergic dysfunction in the prefrontal cortex (PFC). It is hypothesized that functional single nucleotide polymorphism (SNP) rs4680 of the catechol-O-methyltransferase (COMT) gene could mediate the relationship between cognition and dopamine activity in the PFC. Other COMT SNPs could also play a role. Methods: We evaluated the role of three COMT SNPs (rs737865, rs165599, and rs4680) in schizophrenia and their impact on three working memory tasks. For genetic association analyses, 212 individuals with schizophrenia and 257 healthy controls (HCs) were selected. The Visual Working Memory (VWM) Task, Keep Track Task, and Letter Memory Task were administered to 133 schizophrenics and 93 HCs. Results: We found a significant association of rs737865, with the GG genotype exerting a protective effect and the GA haplotype (rs4680/rs165599) exerting a risk effect for schizophrenia. COMT rs4680 AA carriers and rs737865 AA carriers scored lowest on the Keep Track Task. When the genotype*group interaction effect was evaluated, rs165599 exerted opposite effects for VWM and Keep Track task performance in patients and controls, with AA carriers scoring lowest on both tests among controls, but highest among patients. Conclusion: These data support the hypothesis that COMT polymorphisms may be associated with schizophrenia and modulate cognition in patients and controls.
Subject(s)
Humans , Male , Female , Adult , Schizophrenia/genetics , Catechol O-Methyltransferase/genetics , Prefrontal Cortex/metabolism , Memory, Short-Term/physiology , Phenotype , Schizophrenia/physiopathology , Schizophrenia/metabolism , Haplotypes , Catechol O-Methyltransferase/metabolism , Case-Control Studies , Genetic Predisposition to Disease , Polymorphism, Single Nucleotide/genetics , Gene Frequency , Genotype , Neuropsychological TestsABSTRACT
Objective: Schizophrenia is a multifactorial disorder. It is known that a combination of extensive multiple common alleles may be involved in its etiology, each contributing with a small to moderate effect, and, possibly, some rare alleles with a much larger effect size. We aimed to perform a systematic review of association studies between schizophrenia (and its subphenotypes) and polymorphisms in the CNR1 gene, which encodes cannabinoid receptors classically implicated in schizophrenia pathophysiology, as well as to present unpublished results of an association study in a Brazilian population. Methods: Two reviewers independently searched for eligible studies and extracted outcome data using a structured form. Papers were retrieved from PubMed and ISI Web of Knowledge using the search term schizophrenia in combination with CNR1 or CB1 or cannabinoid receptor. Twenty-four articles met our inclusion criteria. We additionally present data from a study of our own comparing 182 patients with schizophrenia and 244 healthy controls. Results: No consistent evidence is demonstrated. Conclusion: Some seemingly positive association studies stress the need for further investigations of the possible role of endocannabinoid genetics in schizophrenia.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Schizophrenia/genetics , Polymorphism, Single Nucleotide , Receptor, Cannabinoid, CB1/genetics , Antipsychotic Agents/therapeutic use , Brazil , Case-Control Studies , Comorbidity , Endocannabinoids/genetics , Genetic Association Studies , Gene FrequencyABSTRACT
Objectives: To compare hair cortisol concentrations (HCC) in drug-naïve first-episode psychosis (FEP) patients and healthy controls and to investigate the correlations between HCC and psychopathology. Methods: Twenty-four drug-naïve FEP patients and 27 gender- and age-matched healthy control subjects were recruited. The Structured Clinical Interview for DSM-IV (SCID-1) was used to confirm/rule out diagnoses, and the Positive and Negative Symptoms Scale (PANSS) was used to assess symptom severity. Hair samples (2-3 cm long) obtained from the posterior vertex region of the scalp were processed in 1-cm segments considering a hair growth rate of 1 cm per month. The 1-cm segments were classified according to their proximity to the scalp: segment A was the closest to the scalp and referred to the month prior to inclusion in the study. Segments B and C referred to the 2nd and 3rd months prior to the time of evaluation respectively. Hair steroid extraction was performed using a known protocol. Results: Two-way analysis of covariance (ANCOVA) with gender and age as covariates revealed a group effect (F1.106 = 4.899, p = 0.029) on HCC. Between-segment differences correlated with total PANSS score and with PANSS General Psychopathology subscale and total score. Conclusions: Our findings suggest that hypothalamic-pituitary-adrenal (HPA) axis, as assessed by long-term (3-month) cortisol concentration, is abnormal in the early stages of psychosis. The magnitude of changes in HCC over time prior to the FEP correlates to psychopathology. HPA axis abnormalities might begin prior to full-blown clinical presentation requiring hospital admission.