White matter disease independently predicts progression from mild cognitive impairment to Alzheimer's disease in a clinic cohort.

BACKGROUND: The contribution of vascular pathology to the rate of progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD) remains unclear.

OBJECTIVE: To ascertain the relative roles of cerebral white matter disease and medial temporal atrophy (MTA) in predicting progression from MCI to AD.

METHODS: MCI patients with baseline MRI and ≥18 months of longitudinal follow-up were evaluated. DSM-IV-TR criteria were used to diagnose conversion to dementia. MTA and white matter hyperintensity (WMH) were quantified using the Scheltens scale and modified Fazekas scale.

RESULTS: Of a total of 171 MCI patients, 79 patients with baseline MRI and longitudinal follow-up were studied. Twenty-three MCI patients who progressed to dementia (MCI-P) were identified corresponding to a 19.4% annual risk of conversion. In MCI-P patients, the mean Mini-Mental State Examination and Montreal Cognitive Assessment decline was 1.3 and 2.9 points, respectively. MTA, periventricular WMH and deep subcortical WMH were significantly greater in the MCI-P cohort. WMH was found to predict MCI-P with an odds ratio of 7.69 (p = 0.03).

CONCLUSION: MTA and deep subcortical WMH independently predict conversion from MCI to AD. Optimization of vascular risk factors among patients with MCI can potentially reduce the conversion from MCI to AD.