TaqIB allele polymorphism of the dopamine receptor D2 gene in patients with endogenous psychoses

The genotype at theTaqIB locus of the dopamine receptor D2 (DRD2) gene was established by PCR in 113 healthy donors and 340 patients with endogenous psychoses. The allele and genotype frequencies in patients with affective psychoses significantly differed from those in controls and in patients with schizophrenia. The proportion of B2/B2 homozygotes decreased with increasing contribution of the affective component to the clinical manifestation of schizo-affective and affective disorders. TheTaqIB polymorphism was assumed to play a role in mood aberrations in patients with mental disorders.     

Polymorphism in the Human Serotonin Transporter Gene in Endogenous Psychoses

Associations of the VNTR-17 and 5-HTTLPR polymorphisms of the serotonin transporter gene with affective disorders, including depression, have been found. These polymorphisms were analyzed in two groups of Russian probands: patients with endogenous psychoses and control individuals without mental disorders (423 and 277 persons, respectively). No associations were found between VNTR-17 genotypes or alleles and the diseases. However, the frequency of10/10 (VNTR-17) homozygotes increased with age in both patients and healthy persons. The results of the analysis of the 5-HTTLPR polymorphism suggest an association of the short (s) allele of the 5-HTTLPR polymorphism with schizophrenia and schizoaffective psychoses, but not with affective disorders.     

Disruption of neurocognitive decision-making mechanisms in depression

To analyze the relationship of disruptions in neurocognitive decision-making mechanisms based on logic and reasoning, or in a situation of uncertainty based on emotional experience (emotional learning) with clinical indices of depression, a multidisciplinary clinical, psychological, and neurophysiological study was conducted in 28 patients suffering from depression (women aged 18–56) and 50 healthy volunteers (women aged 18–55). The intensity of depression was estimated quantitatively by the Hamilton’s Depression Rating Scale (HDRS-17) to qualitatively estimate cognitive functions, the “Ten Words” technique, the Wisconsin Card-Sorting Test (WCST), and the Iowa Gambling Task (IGT) were used; and to assess the functional brain state of all patients suffering from depression, a multichannel recording of the background electroencephalogram (EEG) was made. It was demonstrated that in depression, a neurocognitive deficiency was observed that correlates positively with the intensity of the depressive symptomatology. As well, a reduction occurs in the ability to make decisions based both on logic and reasoning (in the WCST), which is associated with EEG features of hypofrontality, and based on emotional learning (in the IGT test). Only in patients suffering from depression with a reduced ability to make rational decisions based on logic and reasoning was a “compensatory shift” observed toward decision making based on emotions, which leads to relatively higher indices of emotional learning. It is assumed that hypofrontality, which results in difficulties in making decisions requiring logical thought, leads to interruption of subcortical, including hippocampal, structures, an increase in the activation of which is related to better indices of emotional learning.     

Serotonin Type 2a (5-HTR2A) Receptor Gene Polymorphism and Personality Traits in Patients with Major Psychoses

Genetic polymorphism of the serotonin receptor (5-HTR2A) gene has been reported to be associated with the expression of clinical traits characteristic of major psychoses, including schizophrenia and affective disorders. In this study, personality traits of patients with these diseases and the associations of these traits with 5-HTR2A allelic polymorphisms were studied. It was demonstrated that schizophrenic and affective patients with the 2/2genotype of serotonin receptor had lower scores on the anxiety scale and on the anxiety-related hypochondriasis and neuroticism scales than subjects with the 1/1and 1/2genotypes.