March 25, 2022
Many older men and women with memory problems are given a diagnosis of mild cognitive impairment, or MCI, a brain condition in up to one in seven adults over 60 that involves problems with thinking and memory. But having MCI does not mean that you will ultimately develop Alzheimer’s disease or another form of dementia, as it can be reversible in some cases and fairly stable in other cases.
A new study from researchers at the University of Waterloo in Canada and other institutions found that almost a third of 472 older women who were diagnosed with mild cognitive impairment returned to having normal thinking and memory skills over more than eight years of follow-up. Ultimately, fewer than 20 percent of those women who reverted to healthy brain function eventually got worse again and went on to develop dementia.
Study participants were part of the so-called Nun Study, a long-running study of aging and cognition among members of the School Sisters of Notre Dame. All were 75 or older when the study period began, and almost 15 percent were over 90. Most had gotten a college or graduate degree. The researchers had information on their school performance years earlier in such topics as English, Latin and math. They also analyzed writing samples from their school days.
In the study, the women with MCI who did well in school were more than twice as likely to revert to normal cognition than their less educated or academically excelling peers. Getting good grades in English classes when younger as well as a facility to write in ways that used complex grammar and that was rich in ideas and metaphors all seemed to be associated with lower chances of developing of dementia.
Education is thought to build so-called cognitive reserve, a rich network of interconnecting brain cells and pathways that help the brain to function well. Scientists theorize that if some brain cells are lost to Alzheimer’s disease, enough connections remain to keep memory and thinking more intact than it would normally be in the case of a weaker or less complex brain network.
“Possessing high cognitive reserve, based on education, high academic grades and written language skills, may predict what happens years after someone receives a diagnosis of mild cognitive impairment,” said the study’s principal investigator, Suzanne Tyas, a professor in the School of Public Health Sciences at Waterloo. “We found that higher levels of education more than doubled the chances that people with mild cognitive impairment would return to normal cognition instead of progressing to dementia.”
The findings offer some reassurance to people who have Alzheimer’s disease in their families and who are having memory difficulties of their own. Mild cognitive impairment causes memory problems but does not typically interfere with daily activities like driving, getting dressed or preparing meals. And while MCI is generally considered a risk factor for Alzheimer’s, this and other studies show that the brain condition by no means indicates you will ultimately develop the disease.
In the study, it was about as likely that women with MCI would revert to normal cognition than progress to dementia. Other treatable conditions such as vitamin deficiencies and clinical depression can cause cognitive perturbations that are reversible if treated effectively. Overall, about a third of the women with MCI never returned to normal and eventually progressed to dementia. About three percent of the women remained in the MCI stage. And about a third of the women died during the course of the study. The findings were published in the journal Neurology.
“We can’t do much about age and genetics, so it’s encouraging that our findings show that there are other ways to reduce the risk of dementia, such as building cognitive reserve through education and language skills earlier in life,” Dr. Tyas said.
Other studies have shown that regular exercise may also help to stem the progression from MCI to dementia. Last year, for example, researchers in Korea reported that older men and women with MCI who got at least 10 minutes of moderate to vigorous exercise more than once a week were 18 percent less likely to progress to Alzheimer’s disease than their sedentary peers with MCI over the next two to four years.
There is still no cure for mild cognitive impairment or Alzheimer’s disease, and age and genetic factors play a large role in who gets the disease. But, as this and other research shows, there is growing evidence that the risk of developing dementia may be modified by lifestyle factors like cognitive stimulation and challenges, exercise and a heart-healthy diet. And the sooner these healthful behaviors are started, the better.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: University of Waterloo. Maryam Iraniparast, Yidan Shi, Ying Wu, et al: “Cognitive Reserve and Mild Cognitive Impairment: Predictors and Rates of Reversion to Intact Cognition vs. Progression to Dementia.” Neurology, published online February 2022
