Cerebral amyloid angiopathy and visuospatial functioning: Analysis of the clock drawing test

Abstract

AbstractBackgroundCerebral amyloid angiopathy (CAA) contributes to cognitive impairment as well as dementia in the elderly. In clinical cohorts, symptomatic CAA is associated with impairments in executive function and processing speed. Because CAA severity tends to be highest in the occipital and posterior temporal and parietal lobes, it may also affect visuospatial function. We hypothesized that participants with a clinical diagnosis of CAA will have impaired performance on tests of visuospatial function when compared to control, mild cognitive impairment (MCI) and Alzheimer’s disease (AD) participants.MethodParticipants with CAA presented with lobar intracerebral hemorrhage, transient focal neurological episodes, or mild cognitive impairment; met Boston criteria for probable CAA; and did not have dementia. Clocks were scored based on a published 20‐point system (Mendez, JAGS 1992). Clock items were subcategorized by general contours, number items, and hand items (Mendez, JAGS 1992); and by a subset of 9 items correlated in prior literature with visuospatial function and temporal‐parietal hypoperfusion (visuospatial items).ResultData from 53 CAA without dementia, 43 MCI, 30 AD with mild dementia (MMSE ≥20), and 40 control participants were analyzed (mean age 71.6 [SD 7.5]; 47% women). Compared to controls, CAA participants performed significantly worse on total score, hand items, and visuospatial items (Table 1). AD participants performed worse than controls on all components except general contour, and MCI participants did not differ from controls. Among CAA participants, total and visuospatial scores did not correlate with history of stroke, number of microbleeds, or white matter hyperintensity volume (p>0.10).ConclusionMean performance on the clock drawing test is lower in CAA patients without dementia than controls, suggesting visuospatial impairment. This impairment may be related to vascular amyloid deposition in posterior brain regions; however, it was not correlated with typical markers of CAA severity suggesting it may be an early but not necessarily progressive feature. Future research should investigate the mechanisms of visuospatial impairment in CAA—including whether it is related to posterior white matter damage or parieto‐occipital atrophy—and its association with daily function and risk for cognitive decline.