Prevention of CIND by physical activity: Different impact on VCI-ND compared with MCI

Background: Cognitive impairment that does not meet the criteria for dementia (Cognitive Impairment, No Dementia - CIND) is a heterogeneous category with an increased risk of dementia. While greater physical activity is generally associated with a lower odds of both dementia and CIND, whether this effect applies across subgroups is not known. Objectives: To investigate the association between physical activity and the risk of vascular CIND (VCI-ND) or mild cognitive impairment (MCI). Methods: In the Canadian Study of Health and Aging community-dwelling cohort, of 4683 people who were not impaired at baseline, 3945 remained without cognitive impairment at 5 years, 454 were diagnosed with CIND, and 284 with dementia. Incident CIND and VCI-ND (n = 163) and MCI (n = 100) subtypes were investigated in relation to baseline physical activity, stratified by sex. Results: In women, moderate-high exercise was associated with a lower odds of CIND (OR=0.62, 95% CI=0.46-0.84) and VCI-ND (0.34, 0.18-0.63) relative to low exercise. There was no association for men or for MCI. Conclusion: Exercise appears to reduce the risk of VCI-ND in women. Whether the lack of an effect of exercise on the odds of MCI reflects that 'prevented AD' is indistinguishable from MCI is an intriguing possibility that merits further study. (C) 2008 Elsevier B.V. All rights reserved.