Boston naming performance distinguishes between Lewy body and Alzheimer's dementias

Although naming impairment is common among persons with dementia, little is known about how specific error types on naming tasks may differ between dementias. Recent research has suggested that persons with dementia with Lewy bodies (DLB) have more visuospatial/visuoperceptual dysfunction than those with Alzheimer's disease (AD), which may impact their ability to correctly perceive and name objects. Our retrospective study evaluated the presence and frequency of error types among patients with DLB and AD on the Boston Naming Test (BNT). Errors on the BNT were classified into five types (i.e., visuoperceptual, semantic, phonemic, no response, and other), and performance was compared among 31 probable DLB patients and 31 probable AD patients matched for age, gender, education, and overall dementia severity. AD patients' overall performance on the BNT was significantly worse than DLB patients (p<.05). In terms of error types, DLB patients made significantly more visuoperceptual errors (p<.05) while AD patients made significantly more semantic errors (p<.001). Logistic regression revealed that the number of visuoperceptual and semantic errors significantly predicted group membership (p<.005), with an accuracy of up to 85%. Results suggest that error analysis of BNT responses may be useful in distinguishing between patients with DLB and AD.