Summary: A new study reports environmentally induced epigenetic alterations have a greater impact on intelligence that previously believed.
Is there a link between differences in IQ test performance and the activity of certain genes? Researchers from Charité – Universitätsmedizin Berlin have shown that modifications in the structure of a specific gene have a negative impact on individual test performance. This suggests that environmentally-induced epigenetic changes to our genetic material have a greater impact on intelligence than previously thought. Results from this study have been published in Translational Psychiatry.
Stress and adverse life experiences are examples of environmental factors that can affect gene activity, leading to structural changes in our genetic material (genome). These ‘epigenetic changes’ enable the human genome to adapt to its environment, allowing our DNA to be passed on to the next generation of cells, as well as passing on the information that determines whether, and under which conditions, a particular gene will be activated.
This study was led by Dr. Jakob Kaminski and Prof. Dr. Andreas Heinz of Charité’s Department of Psychiatry and Psychotherapy on Campus Charité Mitte. The international team of researchers compared the IQ test results of close to 1,500 adolescents with epigenetic modifications. The study focused on testing genes that are important in dopamine-based signal transmission (dopamine neurotransmission). Dopamine plays an important role in the brain’s reward system and is crucial in modulating a person’s drive and motivation. The researchers were able to demonstrate a link between the epigenetic regulation of dopamine neurotransmission and an individual’s IQ test performance. Epigenetic modification resulted in the dopamine receptor gene being silenced: neurons carried fewer dopamine receptors, and signal transmission was reduced. In this current study, silencing of the gene was associated with lower IQ test results.
Commenting on the results of the study, Dr. Kaminski explains: “We have previously been able to observe links between stress and cognitive performance, particularly in relation to the activity of the dopamine-controlled reward system. Environmentally-induced gene activity now joins the ranks of other factors known to influence IQ test performance, such as poverty and genetic constitution. In this study, we were able to observe how individual differences in IQ test results are linked to both epigenetic changes and differences in brain activity which areunderly environmental influences.” The researchers are hoping to conduct more in-depth studies to determine the extent of environmentally-induced neurobiological modifications, as well as the degree to which these modifications affect IQ test performance.
Source: Jakob Kaminski – Charité
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Original Research: Open access research for “Epigenetic variance in dopamine D2 receptor: a marker of IQ malleability?” by Jakob A. Kaminski, Florian Schlagenhauf, Michael Rapp, Swapnil Awasthi, Barbara Ruggeri, Lorenz Deserno, Tobias Banaschewski, Arun L. W. Bokde, Uli Bromberg, Christian Büchel, Erin Burke Quinlan, Sylvane Desrivières, Herta Flor, Vincent Frouin, Hugh Garavan, Penny Gowland, Bernd Ittermann, Jean-Luc Martinot, Marie-Laure Paillère Martinot, Frauke Nees, Dimitri Papadopoulos Orfanos, Tomáš Paus, Luise Poustka, Michael N. Smolka, Juliane H. Fröhner, Henrik Walter, Robert Whelan, Stephan Ripke, Gunter Schumann, Andreas Heinz & the IMAGEN consortium in Translational Psychiatry. Published August 30 2018.
Epigenetic variance in dopamine D2 receptor: a marker of IQ malleability?
Genetic and environmental factors both contribute to cognitive test performance. A substantial increase in average intelligence test results in the second half of the previous century within one generation is unlikely to be explained by genetic changes. One possible explanation for the strong malleability of cognitive performance measure is that environmental factors modify gene expression via epigenetic mechanisms. Epigenetic factors may help to understand the recent observations of an association between dopamine-dependent encoding of reward prediction errors and cognitive capacity, which was modulated by adverse life events. The possible manifestation of malleable biomarkers contributing to variance in cognitive test performance, and thus possibly contributing to the “missing heritability” between estimates from twin studies and variance explained by genetic markers, is still unclear. Here we show in 1475 healthy adolescents from the IMaging and GENetics (IMAGEN) sample that general IQ (gIQ) is associated with (1) polygenic scores for intelligence, (2) epigenetic modification of DRD2 gene, (3) gray matter density in striatum, and (4) functional striatal activation elicited by temporarily surprising reward-predicting cues. Comparing the relative importance for the prediction of gIQ in an overlapping subsample, our results demonstrate neurobiological correlates of the malleability of gIQ and point to equal importance of genetic variance, epigenetic modification of DRD2 receptor gene, as well as functional striatal activation, known to influence dopamine neurotransmission. Peripheral epigenetic markers are in need of confirmation in the central nervous system and should be tested in longitudinal settings specifically assessing individual and environmental factors that modify epigenetic structure.