MINNEAPOLIS — The gradual buildup of amyloid plaques in the brain is one of the hallmarks of dementia onset. However, not everyone with the same amount of plaque develops the same thinking or memory problems. Scientists have been puzzled by this for years. Recently, researchers with the American Academy of Neurology may have finally found an answer.
Their study finds a variety of lifelong lifestyle factors like participating in clubs, religious groups, and sports or artistic activities appear to promote a so-called “cognitive reserve” that serves as a buffer against cognitive decline and dementia. Educational attainment by age 26, occupation, and reading ability also add to this reserve.
Researchers say one of the biggest takeaways of the project is don’t stop learning. The study found continuing to learn over the course of one’s life may help protect the brain. This held true even among people who had lower scores on cognitive tests in childhood, which is especially notable because earlier research indicates people with low scores in childhood are more likely to have a steeper cognitive decline as they age.
“These results are exciting because they indicate that cognitive ability is subject to factors throughout our lifetime and taking part in an intellectually, socially and physically active lifestyle may help ward off cognitive decline and dementia,” says study author Dorina Cadar, PhD, from Brighton and Sussex Medical School, in a media release. “It’s heartening to find that building up one’s cognitive reserve may offset the negative influence of low childhood cognition for people who might not have benefited from an enriching childhood and offer stronger mental resilience until later in life.”
How much does more engagement build the brain’s cognitive reserve?
This project encompassed 1,184 people born in 1946 in the United Kingdom. Each person took cognitive tests when they were eight years-old, and then again when they reached the age of 69. Next, the team used a cognitive reserve index to combine people’s education level at age 26, their participation in enriching leisure activities at age 43, and their occupation up to age 53. Reading skills at 53 were also gauged as a measure of overall lifelong learning, considered separate from education and occupation.
The cognitive test completed by the participants at age 69 featured a maximum possible score of 100. The average score was 92 (lowest score: 53, highest score: 100).
Higher childhood cognitive skills, a higher cognitive reserve index, and higher reading ability were all associated with higher scores on the cognitive test by age 69 years-old. On average, for every unit increase in childhood test scores, the old-age cognitive test score increased by 0.10 points. Meanwhile, for every unit increase in the cognitive reserve index, cognitive scores increased by 0.07 points on average, and for every unit increase in reading ability, cognitive scores increased by an average of 0.22 points.
On average, those with a bachelor’s degree or other higher education qualifications scored 1.22 points more than those with no formal education. Those who engaged in six or more leisure activities (adult education classes, clubs, volunteer work, social activities, gardening) scored 1.53 points more on average than those who only participated in up to four leisure activities. Regarding occupation, people with a professional or intermediate level job scored 1.5 points more on average than those working jobs deemed partly skilled or unskilled occupations.
Better readers decline slower
Additionally, participants with a higher cognitive reserve index and reading ability tended to see their cognitive scores decline at a slower rate than people with lower scores, regardless of childhood test scores.
“From a public health and societal perspective, there may be broad, long-term benefits in investing in high education, widening opportunities for leisure activities and providing cognitive challenging activities for people, especially those working in less skilled occupations,” adds Michal Schnaider Beeri, PhD, of Icahn School of Medicine at Mount Sinai in New York, who wrote an editorial accompanying the study.
Study authors note that this project had certain limitations. For instance, participants who remained with the study until age 69 were more likely to be healthier, have stronger overall thinking skills, and more socially advantaged than those who did not stick with the project. Thus, these findings may not reflect the general population.
The study is published in the journal Neurology.