Physical activity reduces the risk of dementia in MCI subjects : a cohort study

Background: Leisure activities, particularly exercise, play a protective role against dementia in healthy people, but it is unknown if this protective effect could be generalized to subjects with mild cognitive impairment (MCI). Objective: To investigate the influence of leisure activities on the risk of progression of MCI to dementia. Methods: 176 MCI subjects attending a memory clinic underwent a standardized lifestyle questionnaire between October 2007 and May 2010. Social, cognitive, and physical scores were derived based on the assiduity of interpersonal contacts and on the frequency of participation in individual leisure activities. Subjects were requested to return every 12 months for dementia surveillance. The outcome measure was the risk of dementia associated with social, cognitive, and physical scores. Results: Over a median follow-up time of 2.59 year, 92 (52.2%) MCI subjects developed dementia. Subjects with physical scores in the highest third had a lower risk (HR 0.44; 95% CI 0.23-0.85) of dementia compared with those in the lowest third. No association was found between cognitive or social scores and the risk of dementia. Conclusion: To our knowledge, this is the first prospective clinical study which demonstrates that high levels of participation in physical leisure activities are associated with reduced risk of dementia in subjects with MCI. In line with findings coming from community-based studies on healthy elderly, our finding suggests that the protective role of exercise against the development of dementia can be generalized to MCI subjects seen in clinical practice. Clinicians should encourage MCI subjects to participate in physical leisure activities.