Neanderthal DNA may provide clues about genetic risks for brain disorders and addiction

Summary: The traits with the strongest contribution to Neanderthal DNA were sleep patterns, smoking habits, and alcohol consumption.

source: Estonian Research Council

It has long been known that disorders of the human brain such as neurological or psychiatric diseases run in families, which suggests some heritability. Consistent with this hypothesis, genetic risk factors for the development of these diseases have been identified.

However, basic questions about evolutionary drivers have remained elusive. In other words, why aren’t genetic variants that increase disease risk eliminated during development?

Answering these questions was very difficult. However, new discoveries about events in the deep human past have given scientists new tools to begin unraveling these mysteries: When modern humans moved out of Africa more than 60,000 years ago, they met and mingled with ancient humans such as Neanderthals.

About 40% of the Neanderthal genome can still be found in non-Africans at present, and each individual still carries about 2% of Neanderthal DNA. Some ancient genetic variants may have had 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 disease risk.

Using this approach, a new study from an international team led by researchers from the University of Tartu, Charity Berlin and the UMC Amsterdam Center analyzed the associations of Neanderthal DNA with a large variety of more than a hundred disorders and brain traits such as sleep, smoking and alcohol. Used in the UK Biobank with the aim of narrowing down the specific contribution of Neanderthal DNA to variation in behavioral traits in people today.

The study found that while Neanderthal DNA showed excessive numbers of associations with many traits associated with CNS diseases, the diseases themselves showed no high numbers of Neanderthal DNA associations.

Among the traits with the strongest contribution to Neanderthal DNA were smoking habits, alcohol consumption, and sleep patterns. Using data from other groups such as the Estonian Biobank, the Netherlands Depression and Anxiety Study, FinnGen, Biobank Japan and deCode, many of these findings can be replicated.

Of note are two independent Neanderthal high-risk variants of positive smoking status that were found in the UK Biobank and Japan Biobank, respectively.

“Our results indicate that Neanderthals carry multiple species that significantly increase the smoking risk of people today. It remains unclear what the phenotypic effects of these variants were in Neanderthals.

Michael Dunnemann, associate professor of evolutionary genomics at the University of Tartu and lead author of the study.

“Important associations between Neanderthal DNA and alcohol use and smoking habits may help us reveal the evolutionary origin of addictive behavior and reward-seeking,” added Stefan M. Gold, professor of neuropsychiatry at the Charité, Berlin, who co-led the study.

This indicates the DNA strand
About 40% of the Neanderthal genome can still be found in non-Africans at present, and each individual still carries about 2% of Neanderthal DNA. The image is in the public domain

“It is important to note that sleep problems and alcohol and nicotine abuse have consistently been identified as common risk factors for a range of neuropsychiatric disorders. On the other hand, there are some interesting findings from anthropology that have suggested some social benefits of a higher tolerance for these substances in hunters.”

“Thus, our findings support the hypothesis that it is not brain diseases themselves that have evolutionary explanations but natural selection that shapes the traits that make us susceptible to them in the modern context.”

Neanderthals already inhabited parts of Eurasia more than 100,000 years before modern humans moved out of Africa to populate the rest of the world. The high frequency of some variables associated with different sleep patterns may indicate that these were beneficial outside of Africa – an environment that is determined, for example, by different levels of seasonality and UV exposure than the environment in which modern humans evolved in,” added Dunnemann.

About this genetics and evolutionary neuroscience news

author: Carlos Quiff
source: Estonian Research Council
Contact: Carlos Koiv – Estonian Research Council
picture: The image is in the public domain

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This indicates a brain

original search: open access.
Neanderthal introduction divides the genetic landscape of neuropsychiatric disorders and associated behavioral phenotypesWritten by Michael Dunneman et al. Translational psychiatry


Neanderthal introduction divides the genetic landscape of neuropsychiatric disorders and associated behavioral phenotypes

Despite advances in determining the genetic basis of mental and neurological disorders, fundamental questions about their evolutionary origins remain elusive.

Here, variants provided by ancient humans such as Neanderthals could serve as an interesting research model.

We compared the number of associations of Neanderthal variants with the number of associations of non-archaic variants matched for frequency with respect to human CNS disorders (neurological and psychiatric), nervous system drug prescriptions (as a proxy for disease), and unrelated disease phenotypes in the UK Biobank ( UKBB).

While no enrichment of UKBB Neanderthal genetic variants was observed for psychiatric or neurological disease categories, we found significant associations with specific phenotypes including pain, chronological/sleep pattern, smoking and alcohol consumption.

In some cases, the enrichment signal was driven by Neanderthal variants that represent the strongest genome-wide association. Polymorphisms within the UKBB smoking-associated Neanderthal haplotype can be replicated in four independent genome data sets.

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