Scientists have identified a part of our genetic code linked to the brain’s power to process information, in what they say is the first such link to have been found in the human genome.

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Brain power is influenced by our genes – this study identifies one linked to types of thinking speed.

Quick-thinking agility in middle and later life was put to the test and linked to an area of our genetic material near a gene the authors say has already been linked to autism and personality.

The study concludes: “Our findings suggest that genetic variation in the CADM2 gene is associated with individual differences in information processing speed.”

Published in Molecular Psychiatry, the results are from genome-wide association studies – scanning the complete genetic codes of many people.

This science means health and disease associations can be located on the human genome. Using large numbers of people to ensure the associations are not just individual, small or random effects, increases the reliability of concluding that a particular part of the complete genetic code has a role in a particular part of life.

This study involved some 30,000 people over the age of 45 years, none of whom had dementia, the cognitive decline resulting from brain diseases such as Alzheimer’s and vascular dementia.

Details of each person’s genome were available for analysis and used to find associations with their thinking speeds, to locate genetic variants that may be responsible for differences in cognitive function.

The tests of mental agility included one of processing speed known in research as part A of the trail-making test.

For this test, participants are given a series of numbers up to 25, which are randomly spread out in a space, and the idea is to put them into ascending order under pressure of time, starting the trail at a circle marked “begin” and drawing a line by following the sequence to the point marked “end.”

Executive function was the other part of thinking power put to the test – our higher function in other words.

Included in the evaluation of mental capacity was part B of the trail-making test. For this version, the lines are drawn between alternating numbers and letters, involving an ability to switch mental processing between two types of information – and again the time taken is measured.

Such tests are used in various areas of neuroscience, and wider fields too. In occupational health, the test has appeared as a means to test older drivers’ on-road performance, for example.

Among the researchers was study coauthor Prof. Ian Deary, director of the University of Edinburgh’s center for cognitive aging and epidemiology. He believes processing speed is a “core capability for preserving other mental skills in older age.”

With the results on processing speed gathered, the team looked for correlations with the participants’ genetic variations, and the thinking skills under test found a link with an area of variation near a gene called CADM2, which is also known as Syncam2.

The researchers cite evidence of the CADM2 gene’s activity in the frontal and cingulate cortex in the brain – which are areas involved in thinking speed – and explain the gene is linked to the communication process between brain cells.

Prof. Deary comments on the importance of the findings in the study, which, says the study paper, “provides the most comprehensive meta-analysis of processing speed and executive function genome-wide association studies to date.” He says:

This inkling into why some people’s processing speed is more efficient than others is a small but encouraging advance in understanding the biological foundations of more efficient thinking.”

The authors’ conclusion also notes other roles linked to CADM2:

“This gene is a candidate for autism and personality, but based on the pathway and expression analyses it may also be relevant to a broad range of neuropsychiatric diseases including dementias.”