JOIN USScientists have found that people who have a variant of a longevity gene have improved brain skills such as thinking, learning and memory.
Researchers found that increasing levels of the gene, called KLOTHO, in mice made them smarter, possibly by increasing the strength of connections between nerve cells in the brain.
"This could be a major step toward helping millions around the world who are suffering from Alzheimer's disease and other dementias," said Dena Dubal, an assistant professor of neurology, the David A Coulter Endowed Chair in Aging and Neurodegeneration at the University of California San Francisco (UCSF) and the lead author of the study published in Cell Reports.
"If we could boost the brain's ability to function, we may be able to counter dementias," Dubal said.
People who have one copy of a variant, or form, of the KLOTHO gene, called KL-VS, tend to live longer and have lower chances of suffering a stroke whereas people who have two copies may live shorter lives and have a higher risk of stroke.
In the study, researchers found that people who had one copy of the KL-VS variant performed better on a battery of cognitive tests than subjects who did not have it, regardless of age, sex or the presence of the apolipoprotein 4 gene, the main genetic risk factor for Alzheimer's disease.
The investigators tested a variety of cognitive skills, including learning, memory, and attention. More than 700 subjects, 52 to 85 years old were tested as part of three studies. None had any sign of dementia.
Consistent with previous studies, 20 to 25 per cent of the subjects had one copy of the KL-VS variant and performed better on the tests than those who had no copies.
Performance on the tests decreased with age regardless of whether a subject had one or no copies of the KL-VS gene variant.
The KLOTHO gene provides the blueprint for a protein made primarily by the cells of the kidney, placenta, small intestine, and prostate.
A shortened version of the protein can circulate through the blood system. Blood tests showed that subjects who had one copy of the KL-VS variant also had higher levels of circulating klotho protein. The levels decreased with age as others have observed.
The researchers speculate that the age-related decrease in circulating levels of klotho protein may have caused some of the decline in performance on the cognitive tests.
Researchers then genetically engineered mice to overproduce klotho protein. The klotho-enhanced mice lived longer and had higher levels of klotho in the blood and in a brain area known as the hippocampus, which controls some types of learning and memory.
Similar to human studies, the klotho-enhanced mice performed better on a variety of learning and memory tests, regardless of age.