Visuoperception test predicts pathologic diagnosis of Alzheimer disease in corticobasal syndrome

Objective: To use the Visual Object and Space Perception Battery (VOSP) to distinguish Alzheimer disease (AD) from non-AD pathology in corticobasal syndrome (CBS). Methods: This clinicopathologic study assessed 36 patients with CBS on the VOSP. All were autopsied. The primary dependent variable was a binary pathologic outcome: patients with CBS who had primary pathologic diagnosis of AD (CBS-AD, n = 10) vs patients with CBS without primary pathologic diagnosis of AD (CBS-nonAD, n = 26). We also determined sensitivity and specificity of individual VOSP subtests. Results: Patients with CBS-AD had younger onset (54.5 vs 63.6 years, p = 0.001) and lower memory scores on the Mattis Dementia Rating Scale-2 (16 vs 22 points, p = 0.003). Failure on the VOSP subtests Incomplete Letters (odds ratio [OR] 11.5, p = 0.006), Position Discrimination (OR 10.86, p = 0.008), Number Location (OR 12.27, p = 0.026), and Cube Analysis (OR 45.71 p = 0.0001) had significantly greater odds of CBS-AD than CBS-nonAD. These associations remained when adjusting for total Mattis Dementia Rating score, disease laterality, education, age, and sex. Receiver operating characteristic curves demonstrated significant accuracy for Incomplete Letters and all VOSP spatial subtests, with Cube Analysis performing best (area under the curve 0.91, p = 0.0004). Conclusions: In patients with CBS, failure on specific VOSP subtests is associated with greater odds of having underlying AD. There may be preferential involvement of the dorsal stream in CBS-AD. Classification of evidence: This study provides Class II evidence that some subtests of the VOSP accurately distinguish patients with CBS-AD from those without AD pathology (e.g., Cube Analysis sensitivity 100%, specificity 77%).