Does cognitive and social activity reduce the risk of dementia?

Alzheimer’s disease is characterized by the loss of memory and other cognitive functions. Many observational studies have found that cognitive and social activities are associated with a reduced risk of dementia. However, a recent publication in Lancet Public Health suggests an alternative explanation for these results [1].

In the new study, researchers analyzed data from the UK Million Women Study, an observational study of 1.3 million women who were invited for breast cancer screening at the National Health Service (NHS). Women were screened in 2001 and asked whether they participated in education, art, craft or music groups, and voluntary work. They were screened again in 2006 and asked how many hours per day they read. Overall, more than 800,000 women (average age 60) participated. NHS health records were used to determine whether the women were diagnosed with dementia over an average follow-up of 12-16 years.

Women who reported not participating in cognitive or social activities in 2001 were at a 41% increased risk of dementia less than five years later and a 21% increased risk of dementia 5-10 years later. However, lack of participation in cognitive or social activities was not associated with an increased risk of dementia more than 10 years later. Likewise, those who reported not reading in 2006 were at a more than 200% increased risk of dementia less than five years later and a 37% increased risk of dementia 5-10 years later. However, not reading was no longer associated with dementia risk more than 10 years later.

The pathological brain changes that occur with Alzheimer’s disease precede the cognitive manifestations by more than a decade. The researchers speculate that the association between cognitive and social inactivity and dementia risk less than 10 years later may be related to the ongoing pathological changes that occur in Alzheimer’s disease before cognitive symptoms. With a follow-up period greater than 10 years, cognitive and social inactivity was no longer associated with the risk of dementia, possibly because there is insufficient pathology more than 10 years before dementia onset to reduce cognitive and social activity.

However, other observational studies with long follow-up periods have reported divergent results. For instance, one observational study in 9,550 adults (average age 65) reported that cultural engagement (e.g., going to a museum or gallery) every few months was associated with a 43% reduced risk of developing dementia 12 years later [2]. Another observational study including 800 Swedish middle-aged women (average age 47) reported that increased levels of cognitive activity (e.g., reading, writing, visiting an art exhibit, painting, etc.) were associated with a 34% reduced risk of dementia and a 46% reduced risk for Alzheimer’s disease 44 years later [3].

There are inherent difficulties in observational research. Each study above used a different methodology to assess the type and amount of cognitive and social activity. In addition, each study included individuals who were different ages at baseline (e.g., 47 vs 60-65) and monitored dementia cases with different follow-up periods (e.g., 44 years vs ~12-16 years). Finally, different methods were used to assess dementia. One study used medical health records, one a combination of self-reported diagnosis and questionnaires for family members or caregivers, and one used neuropsychiatric examinations.

Although divergent, these findings may not be mutually exclusive. Cognitive and social activity may reduce the risk of dementia later in life, but pathological brain changes before overt Alzheimer’s symptoms may reduce participation in cognitive and social activities.

Better evidence can be obtained from randomized controlled trials, which are the “gold standard” of biomedical research, because they can test whether an intervention causes a given effect. For instance, the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) trial was a 10-year randomized controlled trial that enrolled over 2,800 healthy older adults (average age 74) [4]. The ACTIVE study found that a specific type of computerized cognitive training over six weeks could reduce the risk of dementia by 29%, 10 years later. Randomized controlled trials remove many of the variables that limit observational studies and provide stronger rationale for a particular intervention.

Cognitive and social activities may reduce the risk of dementia in several ways. Cognitive activities may increase the connections between brain cells, making the brain more resilient despite the presence of Alzheimer’s pathology. In addition, social activities may ameliorate feelings of social isolation and depression, both of which may be associated with an increased risk for dementia. Although results from observational studies sometimes diverge, there is good evidence that cognitive activity throughout life (such as reading, going to museums, or playing a musical instrument) as well as participation in social activities (e.g., participation in groups or clubs, spending time with friends and family, going to church) may be beneficial for brain health.

1. Floud S, Balkwill A, Sweetland S et al. (2021) Cognitive and social activities and long-term dementia risk: the prospective UK Million Women Study. Lancet Public Health  6, e116-e123.
2. Fancourt D, Steptoe A, Cadar D (2020) Community engagement and dementia risk: time-to-event analyses from a national cohort study. J Epidemiol Community Health  74, 71-77.
3. Najar J, Ostling S, Gudmundsson P et al. (2019) Cognitive and physical activity and dementia: A 44-year longitudinal population study of women. Neurology  92, e1322-e1330.
4. Edwards JD, Xu H, Clark DO et al. (2017) Speed of processing training results in lower risk of dementia. Alzheimers Dement (N Y)  3, 603-611.

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