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The research group investigated the genotype of 278 men and women. They were particularly interested in what is known as the tyrosine hydroxylase gene (TH gene). Depending on the expression of the gene, people’s brains contain differing amounts of neurotransmitters from the catecholamine family, to which the neurotransmitter dopamine belongs.
The team also used a questionnaire to record how well the participants were able to control their actions. Women with poorer action control had a genetic predisposition towards higher dopamine levels. Dopamine and action controlWhether someone tends to postpone tasks or tackle them directly depends on the individual’s ability to maintain a specific intention to act without being distracted by interfering factors.
Dopamine could be crucial here. In previous studies, the neurotransmitter has not only been associated with increased cognitive flexibility but also seems to make it easier for information to enter the working memory.”We assume that this makes it more difficult to maintain a distinct intention to act,” says doctoral candidate Caroline Schlüter.
“Women with a higher dopamine level as a result of their genotype may tend to postpone actions because they are more distracted by environmental and other factors.”More susceptible to genetic differences? Previous studies have revealed gender-specific differences between the expression of the TH gene and behaviour. “The relationship is not yet understood fully, but the female sex hormone oestrogen seems to play a role,” explains Erhan Genç.
Oestrogen indirectly influences dopamine production in the brain and increases the number of certain neurons that respond to signals from the dopamine system. “Women may therefore be more susceptible to genetic differences in dopamine levels due to oestrogen, which, in turn, is reflected in behaviour,” says the biopsychologist.