Abstract
The allelic polymorphism of the serotonin transporter's gene 5-HTTLPR is considered as one of the factors determining an individual genetic predisposition to the development of a wide range of affective disorders, including depression. Many studies have shown that the climatic and social conditions of people's life can have a significant impact on the connections of 5-HTTLPR with the risk of depression. The stop-signal paradigm (SSP) is an experimental method allowing evaluating an individual ability to the self-control of behavior in a changing environment. In the SSP experiment, a subject should either press one of several buttons quickly after the appearance of the target stimuli or suppress the already started movement if an inhibitory signal follows the target stimulus. The aim of this study is a research of associations between the allelic the 5-HTTLPR polymorphism and the individual scores of the personal anxiety level, as well as the behavioral and neurophysiological indicators of the ability to self-control over motor reactions in the SSP. The study was conducted among people from three ethno-regional groups: healthy Caucasoids from Novosibirsk, the Mongoloid groups of the indigenous population of the Tuva Republic and Sakha Republic (Yakutia). Genetic, ethnographic, and psychological influences on an individual's ability to control motor responses were compared. The amplitude of the premotor peak of the evoked brain potential was used as a neurophysiological marker of the person's readiness to the execution of target-directed activity. It was revealed that the frequency of the S-allele polymorphism 5-HTTLPR was significantly higher for both mongoloid groups compared to the Caucasoids. The S/S genotype was associated with an increased level of personal anxiety and at the same time with a better ability to the self-control of behavior in the SSP experiment. Anxiety level, participants' sex, ethnicity, and allelic polymorphism 5-HTTLPR had a statistically significant effect on the amplitude of the premotor readiness potential recorded under the SSP conditions in the frontal and parietal-occipital cortical regions. Our data support the hypothesis that the S/S genotype of the 5-HTTLPR polymorphism may be associated with more success in adapting to the climatic conditions connected with high life risk in comparison to L/L and L/S genotypes.
Highlights
The subject of psychological genetics is the identification of molecular markers associated with psychological charac teristics of healthy people and predisposition to the onset of psychiatric and neurological diseases (Eysenck, 1990; Mil ler, Lynam, 2003)
5 we showed that 5-HTTLPR polymorphism is associated with indicators of motor control under event-related po tentials (ERPs) conditions (Karpova et al, 2017)
The two Mongoloid samples differed from each other in the prevalence of alleles of the 5-HTTLPR polymorphism, not as contrastingly as they both differed from the Caucasian sample
Summary
The subject of psychological genetics is the identification of molecular markers associated with psychological charac teristics of healthy people and predisposition to the onset of psychiatric and neurological diseases (Eysenck, 1990; Mil ler, Lynam, 2003). Serotonin neurotransmitter transporter (5-HTT) polymorphism is one of the most extensively studied molecular markers of predisposition to a wide range of mental disorders (Lesch et al, 1997; Arango et al, 2003). The pro moter region of the serotonin transporter gene (5-HTTLPR) contains 16 tandem repeats about 20 bp units. Polymorphism 5-HTTLPR is presented by two allelic variants: long variant contains 16 repeats (L allele) and short variant contains 14 re peats (S allele). It is known, the S allele is associated with a reduced efficiency of the transport function of this protein (Lesch et al, 1996). The long allele contains an A/G single nucleotide polymorphism, with the Lg allele func tionally similar to the S allele (Hu et al, 2005)
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