A large-scale genetic study has identified a total of 1,016 genes that are associated with intelligence, of which 939 added genes were previously unknown to science.
Using a breakthrough statistical method to conduct their study, the international team of researchers found that the genes attributed to high cognitive abilities were also linked to genes responsible for longevity. This insight suggests that intelligent people may live longer than most of their counterparts. More so, intelligent people were seemingly protected from genes that bring Alzheimer's disease, ADHD, and schizophrenia.
On the other hand, the genes responsible for intelligence are also linked to genes that bring an increased risk of autism.
Meta-analysis In 269,867 Individuals
The researchers, headed by Danielle Posthuma, a statistical geneticist from Vrije University in Amsterdam, used a method called MAGMA to perform the genome-wide association study or GWAS of 269,867 people. The participants answered a series of neurocognitive tests that served as an assessment of their intelligence.
The scores from the tests were compared to the participants' DNAs that were analyzed through a process called single nucleotide polymorphisms. This process involved observing the actual gene mutations that are correlated with superior intelligence.
The team was able to detect more than 9 million mutations from the DNA samples of the participants. They also identified 205 regions in DNA, and, as mentioned, a total of 1,016 specific genes related to intelligence. The study noted that 77 of these genes had already been previously identified prior to the present study.
The study also said the majority of the genes for intelligence were found to be located in the "medium spiny neurons" which forms part of the brain's basal ganglia. The latter is comprised of clusters of neurons located deep within the portion of the brain where learning, cognition, and emotion are being processed.
Practical Applications Of The Study
Posthuma said their findings can be significant in the diagnosis of autism, ADHD, and of people at risk of developing depression, Alzheimer's, and schizophrenia. In the future, diagnosis of such conditions may be conducted based on gene analysis. The most ideal application will be designing gene therapy treatments for these mental conditions.
"These results are a major step forward in understanding the neurobiology of cognitive function as well as genetically related neurological and psychiatric disorders," the team wrote in its study published in the journal Nature Genetics on June 25.
Peter Visscher, a geneticist who was not involved in the study, said the findings served as solid evidence of how several genes are working together to make people intelligent and maintain stable minds.