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Study Shows Age-Related Mental Declines Well Before 60th Birthday

Age-related memory loss is widely believed to begin around the age of 60, but new research suggests that memory and other mental declines may commonly occur decades earlier.

British civil service workers subjected to a battery of tests designed to assess brain functioning showed evidence of declines in memory, reasoning, and comprehension as early as age 45.

The study is among the first to attempt to track these cognitive skills among people in their 40s and 50s, and the findings could have important implications for the future research and treatment of age-related dementia, investigators say.

“The (mental) declines among people in their 40s and 50s were modest, but they were real,” says lead author Archana Singh-Manoux, PhD, of France’s Center for Research in Epidemiology and Population Health.

45-Year-Olds Had Memory Loss

Singh-Manoux and colleagues examined data from an ongoing British health study known as Whitehall II.

Over the course of a decade, starting in 1997, roughly 5,200 men in the study and 2,200 women were tested on three separate occasions to assess memory, mental reasoning, and language.

The study participants were between the ages of 45 and 70 when the testing took place.

After taking education level into account, the testing showed declines in memory, reasoning, and various measures of language fluency -- with the exception of vocabulary -- at all age levels.

Over the 10-year evaluation, men in their mid-to-late 40s when testing began experienced a 3.6% decline in mental reasoning, compared to a 9.6% decline among men in their mid-to-late 60s. Similar age-related declines were recorded among women.

The study appears online Jan. 5 in the journal BMJ.

Singh-Manoux tells WebMD that the findings highlight the importance of including younger adults in future studies examining aging, memory loss, and other aspects of age-related mental decline.

In an editorial published with the study, Francine Grodstein, ScD, who studies the impact of aging on the brain, writes that these studies will need to be very large because mental losses before age 65 are very small.

Grodstein is an associate professor in the department of epidemiology at Harvard School of Public Health and an associate professor of medicine at Brigham and Women's Hospital in Boston.

By identifying mental losses in younger adults, the study “sets a new benchmark for future research, and eventually clinical practice,” she writes, adding that future efforts to prevent dementia may need to start in adults as young as 45.

Protect the Heart, Protect the Head?

The findings do not mean that large numbers of adults in their 40s, 50s, and even 60s have significant, unrecognized memory loss, Grodstein tells WebMD.

“The good news for the average person is that the level of decline among people in their 40s and 50s is very small,” she says. “This study certainly doesn’t say that there are a lot of people in their 40s walking around with dementia.”

While the new study did not examine the impact of lifestyle on memory, others suggest that maintaining a healthy lifestyle and taking steps to lower heart attackand stroke risk may also protect against age-related mental declines.

“It increasingly appears that what is good for our hearts is good for our heads,” Singh-Manoux says.