This version of the gene might protect against Alzheimer's disease and prevent dementia, researchers report in the Jan. 13 Journal of the American Medical Association. Earlier work linked the variant to impressive longevity and high levels of HDL, the good cholesterol.
But before running to get your genes tested, be aware that scientists don't know for certain how the gene variant might achieve any of these salutary effects, particularly dementia prevention.
They do know that people harboring the variant form of CETP make less of the CETP protein, and apparently that's better. "What CETP does in the brain is less clear," says study coauthor and neurologist Richard Lipton of the Albert Einstein College of Medicine in New York City.
In the new study, Lipton and his colleagues identified 523 people, average age 78. (Forty were later diagnosed with Alzheimer's or dementia.) Blood samples showed that 21 percent carried two copies of the variant form of CETP (one copy comes from each parent) and 45 percent harbored a single variant copy (from one parent). The rest had two copies of the standard version of CETP (no variant).
Over the next four years, those endowed with two copies of the variant were only one-third as likely to develop dementia or Alzheimer's disease as were those who carried the standard CETP gene. Those harboring one copy of the variant CETP didn't seem to glean protection from it.
"I believe this is areal, but small, effect," says neurologist John Ringman of UCLA "Whether or not it will generalize to the population is an open question."
