Adults with high cumulative cognitive reserve appear to have some protection against dementia, even when brain pathologies show the presence of this problem, according to a 2019 study in JAMA Neurology.
Researchers used data from 1,602 dementia-free participants (average age, 80). They assigned each participant a cognitive reserve score based on self-reported lifelong factors such as education, cognitive activities, and social activity and networks.
During an average follow-up of six years, 386 participants (24 percent) developed dementia, and 747 participants died. All participants were divided into three groups based on their lifespan cognitive reserve scores. The risk of dementia was 31 percent in the lowest third, 24 percent in the middle third, and 22 percent in the highest third. Compared to those in the lowest third, those in the middle category were 23 percent less likely to develop dementia symptoms, and those in the highest third were 39 percent less likely.
Of the 47 participants who died, 611 underwent autopsies, and 241 of them had dementia. Interestingly, those with higher cognitive reserve scores had a lower risk of dementia even when brain autopsies showed that they had had pathologies that should have triggered dementia symptoms.
Considerable data from the past 20 years has shown that not all individuals develop the same severity of symptoms even with similar pathology in their brains. Cognitive reserve may explain this finding.