The pattern of cognitive performance in CADASIL: a monogenic condition leading to subcortical ischemic vascular dementia

OBJECTIVE: Subcortical ischemic vascular lesions, which are closely related to small vessel disease, are a common substrate of cognitive impairment and dementia. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic variant of small vessel disease resulting from mutations in NOTCH3. Mutation carriers almost invariably develop cognitive deficits and eventually dementia. The current study describes the profile of cognitive abnormalities in CADASIL subjects. METHOD: A cross-sectional study of 65 mutation carriers (mean age=47.3 years, SD=10.5) and 30 matched comparison subjects (mean age=47.2 years, SD=14.0) was conducted. Participants underwent a series of assessments that included ratings of global cognition, the cognitive portion of the Vascular Dementia Assessment Scale, and specific tests of executive function and attention with measures of processing speed and error monitoring. RESULTS: CADASIL subjects had pronounced impairments of the timed measures (Stroop II and III, Trail Making Test, symbol digit, digit cancellation). Measures of error monitoring (Stroop III, Trail Making Test, symbol digit, maze task) were also significantly affected but to a lesser extent. Prominent deficits further included verbal fluency and ideational praxis. Recall, orientation, and receptive language skills were largely preserved. Subgroup analyses indicated a similar profile in subjects with early and advanced impairment of global cognitive performance. CONCLUSIONS: The findings highlight processing speed as the most substantial area of cognitive impairment in CADASIL subjects, with less pronounced yet significant deficits in other aspects of executive performance and attention. This profile of cognitive impairment is present at an early stage and enables the construction of targeted test batteries for clinical trials. It is hypothesized that the profile of dysfunction described here represents the core of the cognitive syndrome associated with small vessel disease and subcortical ischemic vascular lesions.