Do we really grow smarter with age?
For some people, the answer is clearly yes, new research suggests. And our genetic makeup has a lot do with it.
A new study from Scotland, published in the journal Nature, found that genetic factors account for 24 percent of the fluctuations in a person's intelligence between adolescence and old age. Lifestyle and environmental factors also play a role, but researchers did not identify which of the many genes or other factors that might be involved.
"The nature-nurture controversy is never more contentious than when it concerns the genetics of intelligence," wrote Robert Plomin, a psychologist at King's College in London, in a commentary accompanying the study. The new research, he said, "may mark the beginning of the end of this controversy."
To conduct their study, scientists analyzed records from 1,940 unrelated individuals whose intelligence was measured first at age 11 and then again at age 65, 70 or 79. The participants also provided blood for DNA analysis.
What they determined was that many of the same genetic factors seem to explain why people differ in intelligence in childhood and old age. They also people with above-average intelligence as children tended to be smarter in old age, as well.
The findings could help scientists better understand Alzheimer’s and other diseases that cause cognitive declines in older people.
“General intelligence is a heritable trait that is a risk factor for both the onset of dementia and the rate of cognitive decline in community-dwelling older persons,” they said.