Mental 'Exercise' May Only Hide Signs of
WEDNESDAY, Sept. 1 (HealthDay News) -- Reading, crossword
puzzles and other mentally stimulating activities have pros and
cons when it comes to Alzheimer's disease, new research
In line with prior research, the study finds that such mental
activity may slow declines in thinking and memory during normal old
But folks who loved these pursuits actually displayed a
hastening of their mental decline once symptoms of dementia began
to set in, the researchers say.
"We think there's a trade-off," said senior study author Robert Wilson of Rush University Medical Center in Chicago. Keeping mentally active means that there is "a little more time during which the person is cognitively competent and independent and a little less time in a disabled and dependent state" once dementia does set in, said Wilson, who is senior neuropsychologist at Rush's Alzheimer's Disease Center.
The findings were published online Sept. 1 in
Previous work has suggested that engaging in cognitively
challenging activities may help ward off the appearance of dementia
in older people. To test this, Wilson and his co-workers tracked
almost 1,200 older individuals over nearly 12 years.
The team assessed each person's engagement in mentally
stimulating pursuits using a 5-point "cogntive activity" scale.
At the time of study enrollment, all of the participants were
free of dementia; by the study's end, 614 people were cognitively
normal, 395 showed mild cognitive impairment, and 148 had
The researchers found that increased cognitive activity among
normal individuals -- things such as listening to the radio,
watching television, reading, playing games and going to museums --
meant that they were less likely to experience cognitive decline
over several years.
Specifically, for each gained point on the cognitive activity
scale, the rate of mental decline fell by 52 percent over 6
But the opposite was true for those who did go on to develop
dementia -- in that case, people who had loved mentally challenging
activities actually showed a quicker mental decline after the
illness took over. In fact, the rate of decline accelerated by 42
percent for each point on the cognitive activity scale, the
Wilson and his colleagues believe that this discrepancy may be
explained by the accumulation of neurodegenerative lesions called
plaques and tangles in the brains of dementia patients.
Previous work has suggested that mentally stimulating exercises
do not actually prevent these lesions from accumulating. Instead,
they allow individuals to remain relatively cognitively normal for
a while longer, even in the presence of those lesions.
However, once the plaques and tangles accumulate to a certain
threshold, high cognitive activity can no longer prevent symptoms
of dementia, and the behavioral signs of the disease appear.
Because people can behave normally for years -- even while brain
lesions are appearing -- at the point at which they're first
diagnosed with dementia, a person with a history of cognitive
activity actually has more plaques and tangles in their brain than
a person who wasn't so cognitively active, Wilson believes.
"The person who has a history of being cognitively active actually has more of the pathology in their brain, and so really has more severe disease," he theorized. "That's why they decline more rapidly from that point on."
According to the authors, the results suggest that mental
exercises help prevent the onset of dementia, but only if they're
started before signs of cognitive impairment appear -- after that
point, the brain is probably too damaged for such interventions to
make a difference.
"The results do suggest that mental exercises help stave off dementia but then increase mental decline after dementia onset," said Charles Hall, professor of neurology at Albert Einstein College of Medicine, New York City. He cautioned that it remains possible that some unknown factor still connects mental activity with these effects.
To be sure that there is a direct causal relationship between
mental exercises and the effects the authors found, "it's really
important that we do intervention studies to test this hypothesis,"
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