It did boost cognitive faculties regardless of a person’s age by the equivalent of about six IQ points
PEOPLE are living longer, which is good. But old age often brings a decline in mental faculties and many researchers are looking for ways to slow or halt such decline. One group doing so is led by Dena Dubal of the University of California, San Francisco, and Lennart Mucke of the Gladstone Institutes, also in San Francisco. Dr Dubal and Dr Mucke have been studying the role in ageing of klotho, a protein encoded by a gene called KL. A particular version of this gene, KL-VS, promotes longevity. One way it does so is by reducing age-related heart disease. Dr Dubal and Dr Mucke wondered if it might have similar powers over age-related cognitive decline.
What they found was startling. KL-VS did not curb decline, but it did boost cognitive faculties regardless of a person’s age by the equivalent of about six IQ points. If this result, just published in Cell Reports, is confirmed, KL-VS will be the most important genetic agent of non-pathological variation in intelligence yet discovered.
Dr Dubal and Dr Mucke made their discovery when they looked at 220 volunteers aged 52 to 85, to study the effects ofKL-VS on ageing. They assessed their volunteers’ faculties of memory, attention, visuo-spatial awareness and language. From these, they constructed a composite measure of cognition.
That measure suggested people with a VS version of the KLgene in their chromosomes had better cognition than those without one. When they analysed data collected by two other groups who work independently on KL-VS they discovered these researchers had found the same thing. That comparison brought the number of people examined to 718, a fifth of whom were possessors of KL-VS.
The six-point IQ gap is an extrapolation, since the cognitive tests did not measure general intelligence directly. But if it is correct, variation in the KL gene could account for as much as 3% of the variation of IQ in the general population (or, rather, in the population from which the researchers’ samples were drawn, namely white Americans). In comparison, the previous record-holders, HMGA2 and NPTN, each account for only half a percent of that variation.