Carrying Neanderthal DNA may be associated with an increased risk of depression and addiction, but certain gene variants may also indirectly protect against schizophrenia. This was shown by a study published on the bioRxiv platform.
Scientists say that approximately 40,000 years ago, the ancestors of Homo sapiens interbred with Neanderthals, inheriting some of their genetic material. Today, up to 2% of the genome of modern humans outside of Africa still contains Neanderthal DNA, despite the fact that much of it has been lost through natural selection.
To assess the impact of this inheritance, the researchers analyzed neuroimaging data from approximately 40,000 individuals, comparing brain structure with genetic variants of Neanderthal ancestry. As a result, they identified 28 genomic regions associated with changes in brain development and morphology.
One major gene, DAAM1 on chromosome 14, was found to be associated with dozens of structural features in the cranial and parietal cortex. The analysis showed that Neanderthal versions of it may even reduce the risk of developing schizophrenia.
However, not all the effects were positive. Variants in the PRDM5 gene, also inherited from Neanderthals, are associated with thinning of certain cortical regions and increased susceptibility to depression, addiction and personality disorders. Another gene, LC13A3, has been found to affect the structure of the brain's white matter and indirectly increase the risk of neurological disorders.
The authors point out that most of the Neanderthal genetic variants affecting the brain were probably unfavorable and gradually disappeared. However, some of them have persisted and continue to have a noticeable, if minor, effect on the organization and function of the human brain.
