A common genetic variant that accelerates normal brain ageing in older people by up to 12 years has been identified by US researchers.
The findings could point towards a novel biomarker for the evaluation of anti-ageing interventions and highlight potential new targets for the prevention or treatment of age-associated brain disorders such as Alzheimer's disease, the researchers said.
"If you look at a group of elderly, some will look older than their peers and some will look younger. The same differences in ageing can be seen in the frontal cortex, the brain region responsible for higher mental processes," said Asa Abeliovich, Professor at Columbia University Medical Centre (CUMC) in the US.
The results, published in the journal Cell Systems, showed that many of these differences are tied to variants of a gene called TMEM106B. About one-third of people have two copies of TMEM106B and another third have one copy.
People who have two 'bad' copies of this gene have a frontal cortex that, by various biological measures, tends to appear 12 years older than those who have two normal copies.
"TMEM106B begins to exert its effect once people reach age 65. Until then, everybody's in the same boat, and then there's some yet-to-be-defined stress that kicks in. If you have two good copies of the gene, you respond well to that stress. If you have two bad copies, your brain ages quickly," Abeliovich explained.
"It's in healthy tissue that you start to get disease. It appears that if you have these genetic variants, brain ageing accelerates and that increases vulnerability to brain disease. And vice versa: if you have brain disease, the disease accelerates brain ageing," he noted.
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