Association among aggressiveness, neurocognitive function, and the Val66Met polymorphism of brain-derived neurotrophic factor gene in male schizophrenic patients.

BACKGROUND: The aim of this study was to investigate the association among aggressive behavior, neuropsychological function, and the Val66Met functional polymorphism of brain-derived neurotrophic factor (BDNF) gene in male schizophrenic patients. METHODS: We examined 51 male patients with schizophrenia who had committed homicide (ie, H-SCZ), 50 male patients with schizophrenia who had not committed homicide (ie, NH-SCZ), and 50 healthy male controls. Patients were evaluated using the Positive and Negative Syndrome Scale, Life History of Aggression, and the Overt Aggression Scale. In addition, patients were given neurocognitive function tests, including Korean-Wechsler Adult Intelligence Scale short form, the Korean version of the Rey Memory Test, the Stroop Test, and the Wisconsin Card Sorting Test. The Val66Met polymorphism of the BDNF gene was also genotyped in all schizophrenic patients. RESULTS: We observed no significant difference between patients in the H-SCZ and NH-SCZ groups, with regard to Positive and Negative Syndrome Scale scores. Total Life History of Aggression (P < .01) and Overt Aggression Scale scores for the most severe episode (P < .01) or for the previous month (P < .05) were higher in the H-SCZ group than in the NH-SCZ group. There were no significant differences in the genotype distribution or allelic frequency of the Val66Met polymorphism between the schizophrenic groups. In addition, we observed no significant differences between H-SCZ and NH-SCZ groups with regard to performance on neuropsychological tests. The Met allele of the Val66Met polymorphism was associated with poor intelligence quotient, memory quotient), learning, and delayed recall in the H-SCZ group. However, genotype did not seem to influence neurocognitive function in schizophrenic patients who had committed homicide. CONCLUSIONS: The neurocognitive tests used in our study were unable to distinguish between violent and nonviolent schizophrenic patients. Furthermore, the Val66Met polymorphism was not associated with aggressiveness in patients with schizophrenia.

New functional single nucleotide polymorphism (Ala72Ser) in the COMT gene is associated with aggressive behavior in male schizophrenia.

A new functional single nucleotide polymorphism (SNP) Ala72Ser in the COMT gene was discovered recently. The purpose of our study is to examine the association between Ala72Ser and Val158Met functional polymorphisms in COMT gene and homicidal behavior in schizophrenia. DNA was genotyped for the Ala72Ser and Val158Met SNPs of the COMT gene in a sample of 93 schizophrenic patients who committed homicide (H-SCZ) and 100 schizophrenic patients who had never committed homicide (NH-SCZ). A statistically significant difference was found in genotype distribution and allele frequencies in SNP Ala72Ser of COMT gene between H-SCZ and NH-SCZ group. In haplotype analysis, the frequency of the combination of high-high activity allele (Ala-Val) was lower in H-SCZ group than in NH-SCZ group (P = 0.000069). Our study showed a highly significant association between a COMT haplotype of two functional SNPs and aggressive behavior in schizophrenia.