In a study from the University of Tartu, scientists found Neandertal DNA may provide answers to why there is a genetic risk for brain disorders.
It has been known for a long time that human brain disorders such as neurological or psychiatric diseases run in families, suggesting some heritability.
In line with this hypothesis, genetic risk factors for developing these illnesses have been identified. However, fundamental questions about the evolutionary drivers have remained elusive.
Recent discoveries about events in the deep human past have handed scientists new tools to start to unravel these mysteries:
when modern humans moved out of Africa >60,000 years ago, they met and mixed with other archaic humans such as Neandertals.
Around 40% of the Neandertal genome can still be found in present-day non-Africans, and each individual still carries ~2% of Neandertal DNA.
Some of the archaic genetic variants may have conferred benefits at some point in our evolutionary past.
Today, scientists can use this information to learn more about the impact of these genetic variants on human behavior and the risk of developing diseases.
In the study, researchers analyzed Neandertal DNA associations with a large variety of more than a hundred brain disorders and traits such as sleep, smoking, or alcohol use in the U.K. Biobank.
The study found that while Neandertal DNA showed over-proportional numbers of associations with several traits that are associated with central nervous system diseases, the diseases themselves did not show any significant numbers of Neandertal DNA associations.
Among the traits with the strongest Neandertal DNA contribution were smoking habits, alcohol consumption, and sleeping patterns.
Using data from other cohorts, several of these results could be replicated. Of specific note were two independent top-risk Neandertal variants for a positive smoking status that were found in the U.K. Biobank and Biobank Japan respectively.
The results suggest that Neandertals carried multiple variants that substantially increase the smoking risk in people today. It remains unclear what phenotypic effects these variants had in Neandertals.
However, these results provide interesting candidates for further functional testing and will potentially help us in the future to better understand Neandertal-specific biology.
If you care about brain health, please read studies about a new drug to stop brain tumor growth, and after COVID-19, watch for these potential heart and brain problems.
For more information about brain health, please see recent studies that drugs and alcohol can hijack your brain, and results showing reducing simple carbs in meals may prevent brain aging.
The study was conducted by Michael Dannemann et al and published in Translational Psychiatry.
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