More than 500 genes linked to intelligence have been identified by scientists – ten times more than were previously known.
Scientists compared variation in DNA in more than 240,000 people from around the world and found they accounted for seven per cent of the differences in IQ.
The study – the largest of its kind – could lead to new treatments for Alzheimer’s disease.
Previous research has suggested “intelligence genes” protect against dementia.
The genes seemed to influence other biological processes, with some also associated with living longer.
Those that contributed to problem-solving powers boosted the process by which neurons carry signals from one place to another in the brain.
Principal investigator Professor Ian Deary, of the Centre for Cognitive Ageing and Cognitive Epidemiology at Edinburgh University, said: “We know environments and genes both contribute to the differences we observe in people’s intelligence.
“This study adds to what we know about which genes influence intelligence – and suggests health and intelligence are related in part because some of the same genes influence them.”
His team pinpointed 538 genes that play a role in intellectual ability – and 187 regions in the human genome connected to thinking skills.
The findings published in Molecular Psychiatry shed fresh light on the biological building blocks of people’s differences in intelligence.
They enabled Prof Deary and colleagues at Southampton University and Harvard University in Boston to predict 7 per cent of differences in IQ between an independent group of individuals – by their DNA alone.
Study leader Dr David Hill, also from the Centre for Cognitive Ageing and Cognitive Epidemiology said: “Our study identified a large number of genes linked to intelligence.
“Importantly we were also able to identify some of the biological processes that genetic variation appears to influence to produce such differences in intelligence – and we were also able to predict intelligence in another group using only their DNA.”
The researchers used data from the UK Biobank – a major genetic study into the role of nature and nurture in health and disease.
This enabled them to compare DNA with IQ scores based on verbal and numerical tests.
Earlier this year it was reported 52 genes linked to intelligence had been uncovered following a similar study of over 78,000 individuals.
People who expressed the genes were less likely to suffer from Alzheimer’s, depression, schizophrenia and obesity.