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

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.

To investigate the association between physical activity and the risk of vascular CIND (VCI-ND) or mild cognitive impairment (MCI).

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.

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.

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.