Exercise as it relates to Disease/Reducing the risk of dementia for adults 65 years of age and older through exercise

This is an analysis of the journal article “Exercise is associated with reduced risk for incident dementia among persons 65 years of age and older” by Eric B. Larson, Li Wang, James D. Bowen, Wayne C. McCormick, Linda Teri, Paul Crane, and Walter Kukull (2006)

What is the background to this research?
Dementia is becoming a major public health problem amongst the elderly. Dementia is characterised by the impairment of brain functions and the progressive deterioration in memory, cognitive function, self-care and personality. Dementia becomes apparent during the later years of an individual’s life and there is currently no cure. Approximately 5 percent of the general population older than 65 and 20 to 40 percent of the general population over 85 years of age have been diagnosed with moderate to severe dementia. There is a general agreement between many studies that encouraging physical activity throughout life may promote brain health, maintain cardiovascular health and most importantly prevent or slow cognitive decline and the development of many types of dementia.

Where is the research from?
This research came from the Center of Health Studies, Group Health Cooperative; University of Washington; and Health Services Research and Development Center of Excellence, VA Puget Sound Health Care System, Seattle, Washington. With support from the National Institute of Ageing.

What kind of research was this?
This is a population-based, longitudinal cohort study of ageing and dementia involving the use of questionnaires, tests and self-reporting. A longitudinal cohort study is an observational research method which gathers data from the same subjects and observes them for the entire study period.

What did the research involve?
The aim of this research is to determine whether regular exercise is associated with a reduced risk for dementia and Alzheimer’s disease. Once the study was approved the participants received the Cognitive Ability Screening Instrument (CASI), which is an initial screening for cognitive function. Once cognitive function was assessed 1895 participants 65 years and older were selected based on their CASI scores being above the 25th percentile (scores 91 to 100). Of these 1895 participants, 155 withdrew after the baseline visit, leaving the final sample size of 1740 participants.

Physical activity was assessed at baseline using a self-report method. Participants were asked the number of days per week they participated in each type of exercise for at least 15 minutes during the last year. Activities included; walking, hiking, aerobics or calisthenics, water aerobics, swimming, weight or strength training and other exercises. Frequency was then calculated by the times participated per week, if they participated at least 3 times per week they were put in the exercise regularly category. There are many factors that can influence the relationship between exercise and risk of dementia, therefore certain tests and self-reported measures were taken to rule out any variables. These included:
 * Performance-based physical function test (PPF)
 * Self-rated health condition – Excellent, very good, good, fair or poor
 * Self-reported medical condition – Diabetes, high blood sugar, heart attack, stroke, surgeries etc.
 * Self-report lifestyle characteristics – Smoking, alcohol consumption, taking dietary supplements

What were the basic results?
The results indicated that regular exercise is associated with a delay in onset of dementia and Alzheimer disease. It is identified that participants that exercised 3 or more times per week had a reduced risk of dementia compared to those who exercised less than 3 times per week. Research also suggests that the participants who had low scores on the PPF test had a greater risk reduction of dementia, compared to those with higher scores.

Eric B. Larson et al further concluded after a mean followup of 6.2 years, that of the 1740 participants:
 * 1185 remained dementia-free
 * 107 developed Alzheimer disease
 * 33 developed vascular dementia
 * 18 developed other types of dementia
 * 121 withdrew from the study
 * 276 died

The study reported an incidence of 13 cases of dementia per 1000 person years for the high exercise group, and 19.7 per 1000 for the low exercise group. With the majority of participants remaining dementia-free, it suggests that the risk of dementia for adults 65 years and older can be reduced through regular exercise.

What conclusions should be taken away from this research?
Regular physical activity is an effective method in reducing the risk of dementia. There have been numerous studies conducted that investigate the relationship between the risk of dementia and physical activity and they have all supported similar results. They indicate that participation in regular physical activity has several benefits on an individual’s health, including reducing the risk of dementia later in life. This research is useful in many ways as it identifies dementia as being one of the most feared illnesses of the ageing population, individuals do not want to lose their independence and quality of life.

What are the implications of this research?
This research has shown that increased levels of physical activity could be an effective strategy for reducing the risk of dementia for adults 65 years and older. There are also many other aspects that could be beneficial to investigate such as; exercise intensity, type of exercise, duration and the relationship among physical function, exercise and the onset of dementia.