Cognitive and physical activities in midlife were linked independently with reduced risk of dementia and dementia subtypes, a longitudinal study that spanned 44 years found.
Women who frequently engaged in cognitive activities — including artistic endeavors, reading, needlework, or social clubs — when they were ages 38 to 54 years were 46% less likely to develop Alzheimer’s disease in late life and 34% less likely to develop dementia, according to Jenna Najar, MD, of the University of Gothenburg in Sweden, and colleagues.
And women who were physically active were 53% less likely to develop dementia with cerebrovascular disease and 57% less likely to develop mixed dementia, they reported in Neurology.
“There have been a number of studies looking at the relationship between activities and dementia risk, but the results have been a bit conflicting,” Najar said in an interview with MedPage Today. “One important thing our research contributes is our long observation period. We have followed these women for more than 4 decades. This is important because low activity levels could be an early symptom of dementia processes.”
While several longitudinal studies have reported that mental and physical activity were tied to lower dementia risk, most have a high mean age at baseline and a short follow-up period. Among studies that have followed individuals for longer time spans, outcomes are mixed. Perhaps the most striking long-term result came from another University of Gothenburg study in 2018 that showed highly fit women were nearly 90% less likely to have dementia decades later.
In this population-based study, Najar and colleagues evaluated 800 women from the Prospective Population Study of Women in Gothenburg, following them from 1968 to 2012. At baseline, the women had a mean age of 47 and were assessed in five cognitive activities — intellectual, artistic, manual, club, and religious — with the frequency of each activity rated as no/low (score 0), moderate (score 1), or high (score 2), using the following guidelines:
- Moderate intellectual activity was reading a book in the last 6 months; high was reading more frequently or writing
- Moderate artistic activity was visiting a concert, theater, or art exhibition in the last 6 months; high was attending more frequently, playing an instrument, singing in a choir, or painting
- Moderate manual activity was needlework in the last 6 months or gardening in the last year; high involved several interests or frequent activities
- Moderate degree of club activity included having a membership; high meant having a board membership
- Moderate degree of religious activity included church attendance at least a few times in the last year; high included church attendance at least 12 times in the last year
The total possible score was 10. The researchers divided participants into two cognitive activity groups: those with scores of 0 to 2 (44% of participants) and those with scores of 3 to 10 (56% of participants).
They also divided participants into two physical activity groups, active (82% of participants) and inactive (17% of participants), based on baseline assessments using the Saltin-Grimby Physical Activity Level scale. The active group engaged in activities that ranged from light physical activity like walking, gardening, bowling, or biking a minimum of 4 hours per week to regular intense exercise like running or swimming several times a week or competitive sports. The inactive group was sedentary, mostly watching television or movies.
At multiple points in the study, psychiatrists or psychiatric research nurses performed neuropsychiatric examinations, using criteria from the Diagnostic and Statistical Manual of Mental Disorders, Third Edition Revised (DSM-III-R).
Over the follow-up period, a subset of women were diagnosed with dementia (n=194), including Alzheimer’s disease (n=102), vascular dementia (n=27), mixed dementia (n=41), and dementia with cerebrovascular disease (n=81), based on established criteria and information from neuropsychiatric examinations, informant interviews, hospital records, and registry data. Mean age at dementia onset was 79.8. During follow-up, 596 women died; they had a mean age at death of 80.
Women with a high level of cognitive activities had reduced risk of total dementia (HR 0.66, 95% CI 0.49-0.89) and Alzheimer’s disease (HR 0.54, 95% CI 0.36-0.82) than women with a low level of cognitive activities. Women who engaged frequently in physical activity in midlife showed a reduced risk of mixed dementia (HR 0.43, 95% CI 0.22-0.86) and dementia with cerebrovascular disease (HR 0.47, 95% CI 0.28-0.78) than physically inactive women. There was no relationship between physical activity and Alzheimer’s disease.
After excluding women who developed dementia midway through the study (to rule out the possibility that they had prodromal dementia at baseline, with less participation in activities as an early symptom), the researchers analyzed the data again and found similar results, except the link between physical activity and dementia was stronger.
The authors noted several limitations to this analysis. They used medical and hospital registry records to identify individuals lost to cumulative attrition, but those sources underestimate the number of dementia cases. Competing risk of death also may have affected results. Cognitive and physical activities were self-reported and assessed only once in the study, at baseline.
The study was supported by the Swedish Research Council, the Swedish Research Council for Health, Working Life and Welfare, the Swedish Alzheimer Foundation, Swedish Brain Power, the Swedish Brain Fund, the Alzheimer’s Association, the Bank of Sweden Tercentenary Foundation, the Söderström-Königska Hospital Foundation, the Gamla Tjänarinnor Foundation, the Handlanden Hjalmar Svenssons Research Fund Foundation, and IRIS Scholarship.
Najar and co-authors disclosed no relevant relationships with industry.