New insight into cognitive decline
However, seniors who have never been married and widowers seem to perform more poorly as they age.
Previous studies on age-related cognitive decline have not
adequately clarified the role demographics and socioeconomic status
might play in the rate of decline. Some small and short-term studies
have found small socioeconomic differences in decline rates, while
others have shown none at all, leaving the issue murky at best.
In a new national study of older Americans 70-plus years of age
(mean age 75), researchers from the David Geffen School of Medicine at
UCLA and the UCLA School of Public Health found that rates of cognitive
decline over a nine-year period were similar across socioeconomic and
racial and ethnic groups. The findings indicate that disparities in
cognitive functioning among older Americans of different groups are
almost entirely due to differences in the cognitive peaks they reached
earlier in life, not to differences in rates of decline.
"It has been known that cognitive performance at any given age
appears to depend on demographic characteristics; the more educated,
for instance, perform better," said lead investigator Dr. Arun
Karlamangla, associate professor of medicine in the
division of geriatrics at the Geffen School of Medicine. "But though
there are differences in the level of performance you start with in
your late 60s, this study's surprise is that the rate of decline in
your 70s is the same for every group."
The study was based on data from 6,476 adults born prior to 1924
culled from the Study of Assets and Health Dynamics Among the Oldest
Old (AHEAD). Participants were tested five times between 1993 and 2002
on various memory and cognition items, including word recall, the
"serial sevens" subtraction test, orientation to time, attention,
language and knowledge of current affairs.
The study found evidence of a link between socioeconomic status
(SES) and cognition, but only at baseline - that is, the first test.
Those with high SES performed better on the first assessment than those
with middle SES, who in turn performed better than individuals with low
SES. These differences, researchers said, could be linked to the
effects of education, such as learned test-taking strategies and the
possible direct effects of education on brain structure.
Researchers did find some demographic variation in rates of
cognitive decline, with older participants declining faster than
younger ones, and widows and widowers and those who never married
declining faster than married individuals.
"The most consistent predictors of faster declines in cognitive
functioning were being old and being single," the researchers wrote.
There are some potential limitations to the study, the researchers
noted. Though few associations between socioeconomic status and the
rate of cognitive decline were found in the AHEAD total cognition
score, an association might emerge in other cognition domains not
examined in the study. There was a greater drop-off during the
follow-up period among participants with low socioeconomic status and
among low-functioning individuals, possibly skewing results.
Additionally, the researchers did not control for differences between
groups in physical health.