Published on: January 31, 2021
by Women’s Brain Health Initiative:
There is an interesting phenomenon that dementia researchers have noticed. Some individuals who have extensive dementia-type damage in their brains experience little to no changes in cognitive function. People who experience this phenomenon are said to have high “cognitive reserve.”
What differentiates those with high cognitive reserve from those with low cognitive reserve – in other words, what makes some people more resistant to age-related brain decline or disease? Many factors are thought to be involved, but collectively these factors have one thing in common: mental stimulation.
Individuals with high cognitive reserve are more likely to lead cognitively stimulating lives.
In particular, more time spent on education, greater occupational complexity, speaking more than one language, and engagement in mentally stimulating leisure activities are some of the factors that have been associated with reduced risk of dementia and slower rate of cognitive decline.
In a review published in April 2019 in Neuroscience Bulletin, Dr. Ai-Min Bao and colleagues summarized previous research on the relationship between various “environmental-stimulation” factors and cognitive reserve. Below is a summary of some of their main findings and conclusions:
Education is thought to be a key contributor to cognitive reserve. Most studies have found that participants with higher education have a lower risk of developing cognitive-decline symptoms. However, the findings about the association between educational attainment and cognitive reserve have not been consistent.
Mentally demanding occupations may provide a protective effect for cognitive function. Complex, intellectual work has been linked with a reduced risk of Alzheimer’s disease (AD), while less complicated, manual labour has been associated with earlier development of AD.
Interestingly, any cognitive protection provided by a complex occupation seems to disappear with retirement. Retiring at an older age has been linked to a later age of AD diagnosis, suggesting that staying mentally active at work for longer might help stave off AD. It is important to note, though, that research on the association between occupational complexity and cognitive reserve has not been consistent either.
Bilingualism has been found in multiple studies to play a role in improving cognitive reserve. In particular, research has found bilingualism to be linked to a delay in the onset of dementia by approximately four years, compared to monolingualism.
Although there is some inconsistency in the findings, the researchers concluded that, overall, bilingualism appears to protect against the symptoms of dementia. And, recent data suggests that multilingualism may be linked to an even stronger protective effect on cognition than bilingualism.
Leisure activities may also give cognitive reserve a boost, although research findings are again inconsistent. Many studies have found a protective cognitive effect from engaging in mentally stimulating and/or socially oriented leisure activities, while others did not find a significant effect.
Despite the mixed findings about the relationship between leisure activities and cognitive reserve, the researchers concluded that leisure activities undertaken throughout the lifespan or in late life seems to be associated with a reduced risk of dementia.
Which leisure activities benefit your brain most? And, does quantity of activity matter?
A wide variety of leisure activities have been associated with pro-cognitive effects, including reading, playing card and board games, solving puzzles, using a computer, and playing a musical instrument.
A recent U.S. study conducted by Dr. Janina Krell-Roesch and colleagues, published in 2019 in Neurology, investigated whether the timing, number, and frequency of mentally stimulating leisure activities in midlife and late life are associated with the risk of developing mild cognitive impairment (MCI). The study involved 2,000 participants with an average age of 78 who did not have MCI at baseline.
At the beginning of the study, the participants completed a questionnaire about how often they engaged in various types of mentally stimulating activities (namely, reading books, using the computer, participating in social activities, playing games, and doing craft activities) in midlife (between the ages of 50 and 65 years) and late life (ages 66 and over). Every 15 months thereafter, for an average of five years of follow up, participants performed thinking and memory tests.
Overall, we found that engaging in mentally stimulating activities was associated with a reduced risk of developing MCI, said Dr. Krell-Roesch, a researcher for the Mayo Clinic’s Translational Neuroscience and Aging Program.
More specifically, the researchers found that the risk of developing MCI was significantly reduced for participants who engaged in:
“Furthermore, we found that the more activities people did in late life, the less likely they were to develop MCI,” continued Dr. Krell-Roesch. “Compared to doing no activities at all, engaging in any two activities was associated with 28% lower risk of MCI, three activities with 45% lower risk, and four activities with 56% less risk.”
These findings support the notion that it is never too late to benefit from mentally stimulating leisure activities. Even though much cognitive reserve accumulates in childhood and early to mid-adulthood – through education and work, for example – it appears that one can continue to grow cognitive reserve throughout the lifespan, even late in life, by engaging in leisure pursuits that challenge the brain.
Playing a musical instrument is another leisure activity that has been linked to higher cognitive reserve.
A 2019 review and meta-analysis conducted by Dr. Sebastian Walsh and colleagues examined three studies of good methodological quality to find out if playing a musical instrument reduces the incidence of cognitive impairment and dementia. The researchers found that playing a musical instrument is associated with large protective effects.
“A study that we reviewed involving twins reported that musicians were 64% less likely to develop MCI or dementia than non-musicians. And, when we analyzed the pooled data from the other two studies we reviewed, we found a 59% reduction of dementia risk,” said Dr. Walsh, an Academic Clinical Fellow at University of Cambridge.
“Our findings provide encouraging evidence in support of the brain-boosting power of playing an instrument; however, the results should be interpreted with caution. They are based on small sample sizes and only provide evidence of a link between playing music and MCI/dementia risk, not evidence of a causal relationship.”
Protecting your cognitive function can be fun!
“There is still much to learn about the relationship between mentally stimulating activities of all types and the risk of dementia. Even though we don’t yet have definitive proof that engaging in mentally stimulating activities decreases the risk of dementia, research is pointing in that direction,” continued Dr. Walsh.
“The thing that appeals to me most about cognitive reserve is that, unlike almost all drug treatments, there are no side effects to mentally stimulating activities. Moreover, activities like learning a new language or playing a musical instrument are fun and add to your emotional wellbeing. It’s a fun, low-risk way to potentially boost your brain health. As we don’t yet have evidence of an age ‘cut-off point’ beyond which there’s no benefit, I would wholeheartedly recommend that people of all ages engage in as many mentally stimulating activities as they enjoy.”
Source: MIND OVER MATTER V11
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