A small but growing body of research suggests that mental exercise can play a role in keeping your brain healthy. The majority of the research has focused on normal aging but there are some studies that have looked at aging individuals with impairment.
Seven randomized controlled trials of cognitive exercise lasting at least 3 months have shown that regular cognitive exercise improves test performance in the same task by about 1 standard deviation. Furthermore, solving reading and math problems can help executive function in every day life. 124 community-dwelling seniors (age range, 70 to 86) in Japan were asked to solve reading and arithmetic problems every day for 6 months. Compared to baseline, they showed improvement in tests of general cognitive ability and executive function.
The effects of mental exercise are specific to the brain areas stimulated, and associate with brain growth in these areas. A study from Norway had middle-aged and elderly healthy volunteers complete an 8-week training program to improve their ability to identify the source of recently learned information (verbal source memory). Compared to controls who did not receive training, these individuals not only improved their verbal source memory, but the thickness of their brain areas involved in this activity increased (right fusiform and lateral orbitofrontal cortex).
Aging individuals with possible cognitive impairment can improve memory and executive function (at least) with specific training. In a study from Johns Hopkins University, 149 older adults were either put on a waiting list or trained to help elementary school children with reading, library skills, and classroom behavior for 15 hr/week for 8 months. The older adults whose baseline executive function was in the impaired range showed a 45-50% improvement in memory and executive function over 8 months, whereas untrained control elderly adults declined in these areas.
Individuals who engage in more cognitively stimulating activity over the course of their life appear to be more resistant to the effects of Alzheimer's disease (AD). The Nun study of 38 nuns found that those with higher "idea density" in their writing as young adults had less cognitive impairment in late life, even though their brains showed AD neuropathological lesions.
School performance may be a measure of engagement in cognitively stimulating activity. Among 725 participants sampled from the population-representative Aging, Demographics, and Memory Study (ADAMS, 2000-2002), those who reported below average school performance were 4 times more likely to have AD than those who reported above average or average school performance.
Lower IQ is a measure of one's cognitive reserve and may predispose to a variety of brain disorders. A population-based, New Zealand study of 1,037 subjects from a 1972-1973 birth cohort were followed up to age 32 years old. A lower childhood IQ was associated with increased risk of developing schizophrenia spectrum disorder, adult depression, adult anxiety, depression and possibly generalized anxiety disorder. Interestingly, higher childhood IQ associated with increased risk of bipolar disorder.
Occupational status also reflects an individual's cognitive reserve, which may be protective against metabolic disorders. A British study of subjects, 40-60 years old, over 10 years, found that higher occupational status was strongly associated with a lower chance of having metabolic syndrome.
Types of mental exercise should include activities which you continuously challenge your brain and learn new things. These include:
Stimulating your brain with new learning and tasks increases your brain activity, and builds reserves of brain cells and connections.
In the case of Alzheimer's disease (AD), researchers suggest that mental exercise reduces the risk of AD by up to 33%. Activities that involve learning something new and then recalling it later are recommended since they activate the parts of the brain that are first affected by AD.