Alzheimer’s trade-off for mentally active seniors

Mental exercise lets seniors outrun Alzheimer’s disease — for a while. Then the race takes a tragic turn for the sharp-minded, a new study finds, as declines in memory and other thinking skills kick into high gear.

After age 65, regular participation in mentally stimulating activities, including doing crossword puzzles and reading, delays intellectual decay caused by Alzheimer’s disease, say neuropsychologist Robert Wilson of Rush University Medical Center in Chicago and his colleagues. But when this debilitating condition finally breaks through the defenses of a mentally fortified brain, it rapidly makes up for lost time, the scientists report in a paper published online September 1 in Neurology.

“The benefit of delaying initial signs of cognitive decline by keeping mentally active may come at the cost of more rapid dementia progression later on,” Wilson says.

His team also found that mental stimulation slows cognitive declines typically experienced by seniors with healthy brains but offers no protection against the onset of memory and thinking problems that fall short of Alzheimer’s disease.

Several recent studies have pointed to a delayed but sharp drop in thinking skills among mentally active people who develop Alzheimer’s disease, remarks neuropsychologist Yaakov Stern of Columbia University College of Physicians and Surgeons in New York City. Unlike the new report, though, those studies did not compare mentally active adults who developed Alzheimer’s disease with those who remained healthy or lost some mental function.

“This cognitive trade-off is a good one if a mentally active person suffers with clinical symptoms of Alzheimer’s disease for a shorter period of time,” Stern says.

Adults who learn to succeed at various intellectual challenges develop cognitive resources needed to cope with early stages of brain disease, Stern hypothesizes.

Wilson’s team studied 1,157 healthy Chicago residents with a range of incomes and ethnic backgrounds, ages 65 and older. To gauge mental activity levels, participants reported how often they watched television, visited museums, played cards or other games, listened to radio and read newspapers, magazines and books.

Each person underwent two or three evaluations over six years. At the end of the period the researchers identified 148 individuals with Alzheimer’s disease and 395 volunteers with milder forms of brain disease.

Those who initially reported high overall rates of mental activity displayed pronounced cognitive declines after being diagnosed with Alzheimer’s disease, Wilson says. Mentally inactive adults who developed the brain disease suffered moderate cognitive hits.

Given individual differences in the severity and onset of Alzheimer’s disease, these findings are consistent with a delay of months or years in cognitive decline among mentally active adults, followed by plummeting mental faculties, the researchers hold.

Biostatistician Charles Hall of Albert Einstein College of Medicine in New York City led a 2009 study that found a similar pattern of cognitive decline among elderly Bronx residents who stayed mentally active. Wilson’s analysis of a larger, more diverse sample of adults supports current thinking that mental training programs (SN: 5/24/08, p. 7) and other cognitive interventions work best if initiated before symptoms of Alzheimer’s disease appear, Hall says.

Researchers are now looking for biological markers of Alzheimer’s disease (SN: 2/18/06, p. 102), which may affect as many as 5.1 million U.S. adults.