Combined effects of mild cognitive impairment and slow gait on risk of dementia

Background: Mild cognitive impairment (MCI) is a high risk of conversion to dementia and gait dysfunction is also a risk for dementia. The goal of the study was to examine if co-occurrence of MCI and slow gait (SG) increases the risk of dementia. Methods: A prospective study was conducted in 3937 older adults who did not have dementia at baseline. Participants were classified into groups based on status of MCI and SG: without MCI and SG (control), without MCI and with SG (SG), without SG and with MCI in a single domain (sMCI) or multiple domains (mMCI), sMCI and SG (sMCI + SG), and mMCI and SG (mMCI + SG). Incident dementia was followed monthly. Cox proportional hazards regression models were used to calculate the hazard ratio for incident dementia in each group. Results: During a mean follow-up period of 43 months, 182 subjects had incident dementia. MCI was a risk factor for dementia and SG increased the risk, even after adjusting for covariates (SG: HR = 1.31 (0.81-2.14), 95% CI = 0.276, sMCI: HR = 1.87, 95% CI = 1.21-2.88, p = .005; mMCI: HR = 3.36, 95% CI = 1.98-5.71, p < .001; sMCI + SG: HR = 3.33, 95% CI = 1.92-5.77, p < .001; mMCI + SG: HR = 5.02, 95% CI = 2.75-9.14, p < .001). Conclusions: Co-occurrence of MCI and SG has a high risk of dementia compared to that of each condition alone. Evaluation of both gait and cognition is useful in risk assessment of dementia.