Declines in mental sharpness and cognitive ability are common in old age ― but when they typically start has been less clear. A new study suggests that in women, the answer could be: much sooner than you thought.
While previous studies have rarely showed cognitive decline occurring before people hit their 60s, new research from UCLA shows that brain aging can begin to show as early as a woman’s 50s.
The longitudinal study, published last week in the journal PLOS One, followed a group of women for 10 years around the time of menopause, and found that their mental processing ability declined an average of 5 percent over the course of roughly a decade.
Cognitive functioning was measured based on two main areas: processing speed, an indication of quickness of perception and reaction; and verbal memory, which tests memory of words and language. Processing speed declined roughly 1 percent every two years, and verbal memory declined an average 1 percent every five years.
The findings are particularly striking given that previous studies on middle-aged women have failed to detect any changes in cognitive function.
“Previous studies on young and middle-aged women had seen increases in scores on cognition testing with repeat testing, instead of declines,” Dr. Arun Karlamangla, a professor of medicine at UCLA and the study’s lead author, told The Huffington Post. “This was thought to be from so-called practice effects. We were the first study to control for practice effects and eliminate confounding by the menopause transition, to uncover declines in processing speed and verbal memory.”
“Practice effects” are when repeated testing using the same tests in the same individuals influences their results, typically for the better.
For the study, the researchers examined data on 2,124 healthy women, and gave them regular tests over the course of six and a half years, on average, to measure for cognitive changes. The women began the study when they were in their late 40s and 50s, and they were tested every one to two years. Most of the women were post-menopausal at the start of the study period.
“Some women decline slower and others declined faster. The next step will be to determine if there are malleable factors that influence the rates of decline."”
So why do women seem to experience cognitive aging earlier than men? It may seem tempting to chalk it up to menopause, but there’s no clear evidence that’s the case. Hormones may play a role, and some studies have suggested that estrogen levels could be to blame. In the current study, however, explicit changes relating to the hormonal shifts of menopause were not seen.
The results also showed significant individual variations, with some women showing signs of cognitive aging much earlier than others. More research is needed to identify the factors that may influence a woman’s risk of early cognitive decline.
“Some women decline slower and others declined faster,” Karlamangla said. “The next step will be to determine if there are malleable factors that influence the rates of decline. If I were to guess, I would conjecture that cardiovascular risk factors ― blood pressure, blood glucose, blood cholesterol, inflammation, etc. ― have strong, possibly causal, links to the rate of decline.”
If you’re concerned about early brain aging, there are many research-tested methods for preventing early cognitive decline at any age. While the study didn’t specifically look at interventions, we know that things like meditation, exercise, yoga, eating a healthy whole foods diet (with lots of leafy greens) and maintaining a positive outlook on life are all powerful ways of protecting the brain from aging.