After studying the same group of healthy women for 10 years after menopause, University of California—Los Angeles (UCLA) researchers found their mental processing ability declined on average by 5 percent.
Cognitive processing speed, which includes speed of perception and reaction, showed an average decline of around 1 percent every two years and verbal memory declined on average around 1 percent every five years.
Previous studies in young and middle aged women (especially those going through the menopause transition) had seen increases in scores on cognition testing with repeat testing, instead of declines.
“Many scholars suspected this was only an artifact of measurement: people in midlife are still good learners and they learn to take the tests better and so improve their scores – a phenomenon called practice effects,” says Dr Arun Karlamangla, the study’s lead author. “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.”
However, while delayed recall showed decline, immediate recall did not show decline. “Nor did the working memory (like the RAM in a computer),” he says.
Dr Karlamangla believes hormones may also play a role. “We did not explicitly see an increase in decline rates relating to the menopause transition, since the majority of the women were 2 years or more past their final menstrual period at the start,” he says.
He also highlights the study did not address prevention.
The next step, Dr Karlamangla says 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,” he says.
While cognitive processing speed goes down gradually with age, even in the 50s, Dr Karlamangla says the take home message is this is analogous to running speed, walking speed and speed of reflexes going down with aging in midlife. “Nothing to worry about – just usual wear and tear from life events and processes. Such changes are part of natural aging and not a harbinger of cognitive impairment in later years,” he says.
Based on the take-home message, he says people shouldn’t worry if they are forgetting where the left their keys or find they are slower to learn to use new technologies than their kids. “Some slowing is natural/usual and it does not mean they are getting dementia,” he says.
Cassandra Szoeke Director of the Women’s Healthy Ageing Project (WHAP), University of Melbourne says it was one of the longest studies done in the United States. She highlights more women than men develop dementia and points to an Australian study which over 15 years measured cognitive abilities of women aged over 45.
It showed while cognitive decline did occur for these women, not everyone declined equally, and some didn’t decline at all.
“We live in a fast paced society and mood can also affect cognitive ability,” she says. “It takes 30 years to develop dementia and more long-term studies looking at a variety of aspects are needed.”