Confluent White Matter in Progression to Alzheimer Dementia.

Abstract

Alongside Alzheimer disease pathology, cerebral small vessel disease (CSVD) contributes to the differential progression rates from mild cognitive impairment (MCI) to dementia. Hence, identification of specific type of CSVD lesions that influence progression is needed. The objective of this study was to evaluate the role of silent CSVD in the progression from MCI to dementia and if confluent white matter hyperintensities (WMHs) pose a higher risk for progression in the clinical setting. Patients with MCI with baseline magnetic resonance imaging and longitudinal follow-up were evaluated. WMH were quantified using visual scoring at baseline (all subjects) and at end of study period (subgroup). Influences of baseline total WMH, baseline confluent WMH, and increase of WMH on progression from MCI to dementia were analyzed. A total of 200 patients with a mean age of 67.9 (SD 8.7) years were evaluated. Progression to dementia was significantly higher among patients with MCI with confluent WMH (55.7% vs. 32.3%; P<0.001). The odds ratio of a patient with confluent WMH progressing to dementia was 2.66. The annual decline in Mini Mental State Examination was significantly higher in those with confluent WMH lesions (-1.60 vs. -1.20; P=0.010). In the subgroup with follow-up magnetic resonance imaging (n=70), patients who demonstrated an increase in WMH had greater decline in annual Mini Mental State Examination scores (-1.79 vs. -0.59; P=0.054). Confluent WMH lesions in MCI are associated with higher rates of progression to dementia.