Quick thinkers are born not made: The speed at which we process new information is written in our genes
The journal article is: "GWAS for executive function and processing speed suggests involvement of the CADM2 gene". Processing speed is one aspect of IQ so this is another genetic contribution to IQ identified.
It has long been agreed that IQ is affected by many genes but an earlier article in the same series ("Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949)" shows that 28% to 29% of the genes affecting IQ have now been identified: "The proportion of phenotypic variation accounted for by all genotyped common SNPs [single-nucleotide polymorphism] was 29% and 28%"
The first article in the series was "Genome-wide Studies of Verbal Declarative Memory in Nondemented Older People: The Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium". It isolated genes for memory performance, also important to IQ
"General cognitive function" is basically just a euphemism for IQ -- less likely to frighten the horses. It is encouraging to see the long list of academics involved in the studies above. Interest in studying "general cognitive function" is obviously widespread, despite its political incorrectness. Layman's account of the first study mentioned above given below
Quick thinkers are born not made, claim scientists. They have discovered a link between our genes and the ability to remain mentally on the ball in later life. It is the first time a genetic link has been shown to explain why some people have quick thinking skills.
Researchers identified a common genetic variant – changes in a person’s genetic code – related to how quickly a person is able to process new information. The researchers say the finding could help understand how the brain works, and why some people develop mental decline, while others do not.
Professor Ian Deary, director of the centre for cognitive ageing and cognitive epidemiology at the University of Edinburgh and a co-author on the study, said: ‘Processing speed is thought to be a core capability for preserving other mental skills in older age.
‘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.’
Professor Deary said the study found one variant with a relation to processing speed. He said: ‘The genetic difference that was significantly related to slight slowing of processing speed was one that about one third of the population have.’
The Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium, which includes experts at the University of Edinburgh, brought together data from 12 different countries on 30,000 people, aged more than 45 years old.
The participants – none of whom had dementia – took cognitive function tests that included tests of simple, repeated coding under pressure of time.
Researchers then processed the results alongside details of each person’s genome to identify genetic variants or changes associated with speed of thinking skills.
People with slower processing speed overall were found to have variants near a gene called CADM2.
The CADM2 gene is linked to the communication process between brain cells - the gene is particularly active in the frontal and cingulate cortex in the brain, which are areas of the brain involved in thinking speed.
Professor Deary said the study examined the genetic contribution to processing speed differences among middle-aged and older people.
‘This is important because, as people age, when processing speed slows down there tends to be reduced efficiency of other thinking skills too, like reasoning executive functions, and some aspects of memory,' he said.
‘So it is important to understand the mechanisms by which people differ in their processing speed.'
Lead researcher Dr Carla Ibrahim-Verbaas, resident in Neurology at Erasmus University Medical Center in Rotterdam, said: ‘We have identified a genetic variant which partly explains the differences in information processing speed between people.
‘Our study confirms the likely role of CADM2 in between-cell communication, and therefore cognitive performance. It is of interest that the gene has also been linked to autism and personality traits.’
The study complements two other recent discoveries by the CHARGE team, which identified genetic variants associated with memory performance and general cognitive functioning in older adults.
The study, published in Molecular Psychiatry journal, involved researchers in Australia, Austria, Croatia, Finland, France, Germany, Holland, Iceland, Ireland, Italy, the UK and the US.