ABSTRACT
Background: The world’s older population is growing dramatically. Consequently, the incidence and prevalence of dementia have also increased. According to The World Health Organization (WHO), over 50 million people worldwide have dementia. While there is no cure for the most common types of dementia, there is extensive research on potentially modifiable risk factors for dementia. Findings from several systematic reviews and meta-analyses of observational studies found that physical activity, a modifiable risk factor, aids in preserving cognitive function and decreases the risk for dementia. Several studies have provided evidence of physical activity’s positive effect on the quality of life of the aging population, other studies have also found that overall, women older than 65 years of age are more sedentary and more physically inactive than men in the same age group and have a higher risk of dementia at old age. There are however contradicting results from observational and interventional studies on the association between modifiable risk factors such as physical activity and dementia risk in women. The objective of this study is to investigate the association between physical activity level and dementia risk in women.
Methods and measurement: Data from 4,670 women who participated on both HUNT3 and HUNT4 +70 between the ages of 55 and 75+ was utilized. After excluding participants with missing data on physical activity level, and confounders, 3,555 participants with an average age of 66.68 years (SD 5.74) were included in this prospective study. Data on self-reported physical activity was collected from HUNT3 questionnaires. The physical activity variable was categorized as “hard activity” (causing perspiration or panting) and “light activity” (not causing perspiration or panting), each with activity durations from: none, under 1 hour, 1-2 hours to 3 or more hours during the week. Two clinical experts made independent diagnoses of dementia and mild cognitive impairment by applying the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic criteria for each participant in HUNT4 70+. Logistic regression was used as an analytic method. The results were presented as odds ratio (OR), with a 95% confidence interval (CI). Age, level of education, marital status, diabetes, history of cardiovascular disease CVD, hypertension, depression, body mass index, smoking status, frequency of alcohol intake, and insomnia were identified as potential confounders based on literature review findings.
Results: In total, 356 (10%) participants were diagnosed with dementia; 17 (20%) of participants taking part in no activity were diagnosed with dementia as well as 146 (13.1%) of participants taking part in light activity for less than 3 hours per week, 101 (12%) participants taking part in light activity for 3 or more hours per week, 72 (6.0%) taking part in hard activity for less than 3 hours per week, and 20 (6.4%) of participants taking part in hard activity for 3 hours per week. A protective association between physical activity level and
a lower risk of dementia diagnosis in women was found. Compared to those who were inactive, ‘Hard’ activity of less than three hours per week showed the greatest reduction of dementia diagnosis compared to no physical activity (OR 0.501, p= 0.033, 95% CL 0.265- 0.947).
Conclusions: Those who engaged in hard physically activity for less than 3 hours a week had a statistically significant reduction in dementia diagnosis. More research on physical activity and risk of dementia in women is needed.
Keywords: Physical Activity, Aging, Dementia, Women, HUNT, Prospective Study.