Mobility decline of unknown origin in mild cognitive impairment: an MRI-based clinical study of the pathogenesis.

Mobility dysfunction of unknown origin predicts dementia in the elderly and is associated with periventricular leukoaraiosis (LA), another predictor of dementia of still controversial pathogenesis, in the elderly with mild cognitive impairment (MCI). Thus, this study examined which gait and balance parameters best correlate with periventricular LA to better understand the pathogenesis of mobility decline in MCI. High resolution MRI and detailed mobility assessment were performed in 61 subjects (72 years+/-5) with MCI. Cognitive assessment included Free and Cued Selective Reminding Test (FCSRT) and the Trail Making test part B (TMB). Mobility assessment included reports of falls in the previous 6-month period, the walking while talking test, the timed "up and go test" (TUG), measurement of fast gait speed, the standing test and the one-leg standing test. There was an association between marked periventricular LA and slow postural changes, slow gait (TUG and gait speed), altered balance (standing test and one-leg standing test), altered walking while talking test. But after adjusting for age and ventriculomegaly on a logistic multiple regression model, performance on the TUG test was the only clinical predictor of periventricular LA (>10 s, P=0.002). Poorer TUG performances were more frequent with vascular than Alzheimer's disease-like profiles on the FCSRT and TMB tests (P=0.01). In conclusion, the clinical profile of patients demonstrating a main MR brain correlate of mobility dysfunction supports a main pathomechanism of subtle vascular extrapyramidal dysfunction in MCI.