Conditioning the Brain for Long-term Mental Fitness

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We always talk about the importance of physical fitness, but rarely about mental fitness even though it's just as important for maintaining a healthy and good quality of life for the long term. The body evolves with physical challenges, and thus, the brain with mental challenges. Let's see how.

1. Early-life education attainment

Low educational attainment is defined as education at the level of lower secondary and below.

In a 2014 study in Lancet Neurology, a team of scientists conducted a statistical analysis of multiple meta-analyses that assess risk factors in Alzheimer’s disease, a neurodegenerative disease involving loss of cognitive abilities, such as memories and concentration.

They found that, globally, the highest modifiable population-attributable risk (PAR) for Alzheimer’s disease is low educational attainment — at 19.1%. This means that 19.1% of Alzheimer's disease cases can be prevented if the risk factor — low educational attainment — was addressed.

In another meta-analysis study published in 2017 in PLOS Medicine, scientists combined data from 14 longitudinal studies from 12 different countries that investigated risk factors in cognitive decline. They discovered that each additional year of education was associated with better cognitive competence across all domains — memory, language, processing speed, and executive functioning.

2. Midlife occupational complexity

High occupational complexity demands daily novel mental stimulations. Examples of such jobs include teachers, mechanics, project managers, doctors, authors, and researchers, among others. By contrast, jobs involving repetitive work such as housekeepers and factory workers are considered as low complexity.

Karp and colleagues from the Aging Center Research in Sweden followed 931 participants without dementia for over 6 years. They published their research in 2009, showing that those with higher occupational complexity had a lower risk of developing dementia in later life. (The most common type of dementia is Alzheimer's disease.

This protective effect was stronger with data-centred jobs involving analyzing and synthesizing data — with a relative risk of 0.52 — that is, a 48% lower risk (1-0.52 = 0.48). The good news is that this effect remains significant even in those with low educational attainment, as the authors noted: “…highest levels of work complexity may modulate the higher dementia risk due to low education.”

Other population-based studies are also in alignment wherein high occupational complexity (mainly people- and data-centred jobs) were associated with:

3. Late-life mentally-stimulating leisure activities

A few examples include leisure activities like sewing, reading, chess, card games, and playing a musical instrument.

In a meta-analysis published in 2005 in Psychological Medicine, scientists harmonized 7 studies pertinent to mental activities in late life and the risk of dementia. All 7 studies reported a positive protective effect. The pooled odds ratio from the 7 studies was 0.5, meaning that the elderly that often engage in mental activities were 50% less likely to develop dementia than those who did not. This effect remains significant after controlling for variables such as education, occupation, age, and general health.

Quoting the authors: “…increased complex mental activity in late life was associated with lower dementia rates independent of other predictors; a dose-response relationship was also evident between extent of complex mental activities in late life and dementia risk.”

Studies later onward also corroborated this finding wherein increased late-life mental activities were associated with:

4. Lifetime mental engagement

Published in PLOS Medicine in 2017, a 9-year longitudinal study comprising of 2,368 participants investigated if there's any relationship between the risk of dementia and lifetime mental activities. They showed that, on their own, early-life, middle-life, and late-life mental activities safeguard against dementia. But this protection became stronger when mental activities at all three stages of life combined — resulting in about 60% lower risk of dementia.

As the authors emphasized: “cumulative exposure to reserve-enhancing factors over the lifespan was associated with reduced risk of dementia in late life, even among individuals with genetic predisposition.” (Dementia is partly genetics in nature, with the APOE4 allele being the greatest known genetic risk factor for Alzheimer's disease).

5. The brain ‘evolves’ with mental challenges

Neuroimaging techniques have shown that individuals with higher education attainment have a unique brain profile. There was an increase in the brain volume and cortical thickness in the medial prefrontal cortex, orbitofrontal cortex, and anterior cingulate. Further gene analyses also revealed that these brain regions have enhanced gene expressions pertinent to neurotransmission and immunity.

The authors of this research, thus, concluded that: “Our results point to a distinctive enrichment with certain biologic pathways that may equip these regions with a higher capacity for plastic change in response to lifetime intellectual enrichment and potentially also a higher resilience to age-related pathologic brain changes.”

Like individuals with high educational attainment, more complex occupations have also been associated with a distinct brain structure. Published in Frontiers of Neuroscience in late 2021, Habeck and colleagues performed neuroimaging on 277 adults.

They quantified “structural brain health” with the formula below.

Brain health = [z(global thickness) + z(mean tract integrity) −z(log-WMH)]/3

  • Global thickness refers to the brain volume or thickness of the cortex.
  • Tract integrity refers to the stability of nerve fibres of the white matter.
  • WMH stands for white matter hyperintensities wherein brain imaging reveals an increased brightness/intensity of the white matter, which means that the white matter is degenerating.

They discovered that more complex jobs — involving problem-solving, leadership, and information processing — correlated positively with improved brain health. These researchers also confirmed that this correlation was not due to education, intelligence, or gender.

Further, in individuals with higher lifetime engagement in mental activities, the rate of hippocampal shrinkage was slower than in those with lower scores. The hippocampus is a region deep in the brain, known for its cardinal roles in learning and memory, and it is the main source of adult neurogenesis throughout life.

So, in the end, while physical fitness benefits the body and brain, don't forget mental fitness for true brain health.

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