January 25, 2005

‘Alzheimer’s Gene’ Affects Even Healthy Seniors

Causes problems with prospective memory, researchers discover

HealthDayNews -- Even if they're healthy, older people with the higher-risk genotype for Alzheimer's disease can suffer major problems with prospective memory -- the ability to remember what they need to do in the future, such as take medications or make a doctor's appointment, a new study says.

People who carry the high-risk e-4 allele on both of their ApoE genes are eight times more likely to develop Alzheimer's as non-carriers. People with the high-risk allele on only one ApoE gene are three times more likely to develop Alzheimer's than non-carriers, according to the research.

University of New Mexico researchers studied a group of 32 healthy, dementia-free adults between 60 and 87 years old. Half of them carried the e-4 allele and half did not.

The study participants were asked to do a prospective memory task that required them to remember to write a specific word when they saw a target word. Far more often than the non-carriers, the e-4 carriers forgot to remember to write down the specified word when they were supposed to, meaning they forgot to do what they meant to do, when they meant to do it.

The findings counter the prevailing view that the e-4 allele has only subtle, undetectable effects on a carrier's cognition, the researchers said.

In light of the study results, doctors might consider helping even healthy e-4 carriers to improve their prospective memory, the study authors said. The study also suggests that testing prospective memory may prove useful as an early diagnostic tool for Alzheimer's disease (AD).

"Our sample of carriers were healthy as far as we could tell, but our assessments were not as sensitive as some of those used at the major Alzheimer's research centers. It might well be that some of our carriers were in early AD stages that were not yet detected," study co-author Mark McDaniel said in a prepared statement.

The study appears in the January issue of Neuropsychology.

More information

University of New Mexico

The U.S. National Institute on Aging has more about Alzheimer's disease genetics.