Cognitive function and health appear to be genetically linked, according to research published in Molecular Psychiatry. The study was carried out by an international team from the US, the UK and Germany.
In some cases, the illness appears to lead to cognitive impairment; other instances suggest that lower cognitive function in early life indicates a higher risk for a number of mental and physical conditions later on.
Previous studies have suggested that lower educational attainment and poor health outcomes often go together. A study of twins has highlighted common genetic effects linking cognitive levels with lifespan.
Cognitive function shows signs of heritability, as do many physical and mental illnesses. This has prompted researchers to look at the overlap between the two, in a search for genetic clues.
The investigation, led by researchers at the University of Edinburgh in the UK, examined data from the UK Biobank for around 100,000 people.
The team wanted to investigate whether illness causes a loss of cognitive functioning, or if an existing cognitive impairment indicates a higher risk, or if the same cause underlies both.
The subjects’ cognitive level, assessed through mental test data, was compared with the 22 health indicators and the results of their genome.
The data were for tests on reaction time, memory and verbal-numerical reasoning. Educational attainment was also considered, where, incidentally, if a person did well in one of the three categories, they also tended to do well in the others.
The selected health traits included vascular-metabolic diseases such as coronary artery disease, stroke and type 2 diabetes, and neuropsychiatric disorders, including Alzheimer’s, ADHD and bipolar disorder. Blood pressure, body mass index (BMI) and cranial measurements were also considered.
There was an overlap between genetic traits related to some diseases and those pertaining to thinking skills, with scores on educational attainment showing a significant genetic correlation with 14 out of 22 health-related traits.
Data gathered from previous genetic studies were used to confirmed the findings.
Co-author Dr. Stuart Ritchie told Medical News Today:
“We found that there are many overlaps: to take one example, genes related to being taller are also related to obtaining a college or university degree. […] People with more genes linked to cardiovascular disease tended to have lower reasoning ability. […] Interestingly, some results were in the opposite direction: people with more genes related to autism (but mostly not with a diagnosis of autism) had a slight tendency towards higher reasoning scores and were more likely to have a degree.”
Dr. Sarah Harris, a lead author, told MNT that the same genes that increase the risk of conditions such as autism, bipolar disorder and schizophrenia may be associated with higher cognitive abilities and greater educational attainment. She added that environmental factors also contribute to these conditions.
In light of the findings, the researchers believe that genetic factors may underlie at least some of the association between educational attainment and health. In other words, specific genes may contribute to both cognitive and health-related traits.
They also predict that some currently healthy individuals who have lower cognitive function and lower educational attainment may be at risk for coronary artery disease, type 2 diabetes or high blood pressure.
Further possible interactions include the impact of genetic variants associated with health conditions on cognitive ability, for example through the use of medications to treat disorders. Similarly, cognitive factors could affect health, perhaps through guiding lifestyle choices.
The researchers stress the importance of investigating biological pathways that influence both cognitive function and health-related traits.
Previous research published by Medical News Today has suggested a genetic link between schizophrenia and creativity.