Intellectually challenging activity of various types has been associated with a reduced risk of dementia in longitudinal studies, but there are currently no published randomized controlled trials to provide first level of evidence on this. Daily mental activities have been associated with a decreased risk of all-cause dementia, while the Bronx Aging Study demonstrated that a high level of participation in cognitive leisure activities is associated with a decreased risk of amnestic MCI in community dwellers. In the Washington Heights Study, participants who engaged in a higher level of leisure activities (self-reported participation in over 6 among 13 activities versus a low activity level) in the previous month were less likely to develop all-cause dementia. A recently published follow-up study of a RCT of cognitive training appeared to show sustained improvement in specific cognitive performance up to 5 years after the intervention. A group of researchers recently showed that continuous cognitive activation is associated with reduced evidence of MCI development and that the level of cognitively stimulating activity in old age is related to the risk of developing dementia. However, as in the previous studies, the assessment and collection data of cognitive activity participation was performed through a pooled analysis of past and current frequency of participation in several activities based upon a structured questionnaire containing tens of items. The additional problem in the interpretation of the results complicating the frequent inclusion of physical activity among leisure activities is that the latter include extremely different stimuli going from reading books or newspapers, to writing for pleasure, doing crossword puzzles, playing board games or cards, participating in organized group discussions, and playing musical instruments, among others. Some of these activities intended as “cognitive” are also social ones, and therefore the interpretation of their role is biased by another important component of a good cognitive performance, that is, socialization.
Once again, similarly to the preventive aspects of physical exercise, there are still a number of reasons that should motivate people to partake in continuous cognitive stimulation in healthy and cognitively impaired subjects. These are based upon the “use it or loose it” concept and include their role as a part of a healthy lifestyle. The latter include the performance of cognitively stimulating activities according to personal interests, abilities and education, and, in demented patients, the prescription of activities that reduce passive behaviors and increase engagement to cognitive and physical activities.
So as far as evidence supports, it is best to engage in regular mental activity that promotes new learning, which you enjoy and get satisfaction from, say 30 minutes per day, 4 to 5 times per week. Several studies have suggested that individuals who are more mentally active have reduced risk for cognitive deficits later in life.
It is now known that when people become retired, they start having cognitive problems. This is most likely due to the drastic change in activity level – one day you are multitasking and working hard, meeting new people, challenging yourself at many levels, and the next, you are home and trying to adjust with a very new environment, which in most cases is not as stimulating as a regimented work environment. As a result, the brain suffers. Research shows that there is a significant negative causal impact of retirement on cognitive functioning. Although the effect of retirement on cognitive functioning is not instantaneous, most of the drop occurs at the beginning of the retirement period when the change is most drastic. The decrease in activity patterns causes loss of cognitive skills, while stimulating mental activities increase them (the “use it or lose it” hypothesis), and suggest that retirement plays a significant role in explaining cognitive decline at older age. Of course, the level of cognitive decline depends on the type of professional activity for the individual while employed: physical versus intellectual work; light versus heavy workload; stressful work or not. Some studies have shown that intellectually demanding jobs during adulthood are associated with better cognitive functioning in later life, whereas manual labor is associated with worse cognitive functioning. They show that individuals have some control over the evolution of their cognitive functioning through the activities they undertake. As a matter of fact, for the aging population, the World Health Organization recommended education and learning opportunities throughout the life course, to recognize and enable the active participation of people in economic development activities, formal and informal work and voluntary activities as they age, according to their individual needs, preferences and capacities; and to encourage people to participate fully in family community life, as they grow older.