People at genetic risk for Alzheimer's age mentally just like noncarriers
Australian researchers say that a genotype that heightens the risk for Alzheimer's disease does not contribute to cognitive change during most of adulthood. The largest study of its kind has found that carriers and non-carriers show the same type and extent of normal age-related cognitive declines, decades before carriers start to more often develop symptoms of dementia. The findings suggest that the higher-risk genotype acts only in later years to layer disease on top of normal aging.
The findings appear in the January issue of Neuropsychology, which is published by the American Psychological Association (APA).
The study may help rule out the possibility of very early Alzheimer's as the cause of the declines among carriers before they reach old age. Write the authors, "[Alzheimer's disease] processes may occur later in the lifespan and add to normal cognitive aging to produce a dementia syndrome."
The study confirmed that carriers of the APOE4 gene type (allele), which confers higher risk for Alzheimer's, are just like other people their age throughout most of adult life in terms of core mental functions. Previous findings had been unclear. Lead author Anthony Jorm, PhD, DSc, explains, "Although some areas of cognitive decline begin from early adulthood onwards, this is not due