Is our virome lowering our intelligence?

We have talked about the virome and its possible substantial impact on human health on this blog before.  Lately, the virome has been getting a lot of press about its potential beneficial aspects, but today we want to discuss a negative one.  A paper was recently published in the Proceedings of the National Academy of Sciences that identified a specific virus in the virome that may be directly affecting the brain, and lowering our aptitude for spatial awareness and attention. 

Researchers were testing the oral microbiome of a cohort of people who were also taking intelligence tests as part of a separate, unrelated, study.  After genome sequencing they noticed the conspicuous existence of a virus, known as Chlorovirus ATCV-1, in about half the study population.  This virus was known to exist in algae, but had never been identified in humans, and there it was, affecting half there population.  Moreover, the virus cut across all demographics in there study, and was not related to age, race, or gender.  When the scientists compared the intelligence tests of those who had the virus versus those that did not, those that had the virus scored slightly less on tests involving spatial awareness.  However, they are quick to note that other tests for intelligence were unaffected.  They reiterate that these scores were related to the existence of the virus and not any specific demographic.

The scientists tried to recreate these results in mice.  They infected a group of mice with the virus and compared its scores on spatial tests with a control group.  The group that had the virus scored considerably lower on the tests.  When they measured specific genes that were affected in the infected mice they discovered some that related to dopamine regulation, which is known to be critical to memory formation and learning. 

Overall this fascinating study not only identified a new member of our virome, but showed that this virus may be altering our spatial reasoning abilities.  So the next time your significant other yells at you for getting lost, just blame it on your virome!