Extrapyramidal Signs and Cognitive Subdomains in Alzheimer Disease.

Objective: Extrapyramidal signs (EPS), commonly observed in Alzheimer disease (AD), predict cognitive impairment and functional decline. This study investigated the association between EPS and five cognitive subdomains in a large number of participants with AD. Design: Cross-sectional analyses of the nationwide Clinical Research of Dementia of South Korea (CREDOS) study, 2005-2012. Setting: Multicenter clinical settings. Participants: 1,737 participants with AD drawn from the CREDOS study. Measurements: The EPS group was defined by the presence of at least one EPS based on neurologic examination. We assessed five cognitive subdomains: attention, language, visuospatial function, memory, and frontal/executive function using the Seoul Neuropsychological Screening Battery-Dementia version. The associations of EPS with each cognitive subdomain were analyzed with a multiple linear regression model after controlling for confounding factors: sex, age, years of education, severity of dementia (Clinical Dementia Rating Sum of Boxes), and white matter hyperintensities. Results: 164 AD participants (9.4%) had EPS. AD participants with EPS showed lower performance compared with those without EPS in two cognitive subdomains: attention and visuospatial function. The language, memory, and frontal/executive subdomains did not differ between the EPS-positive and the EPS-negative groups. In addition, we found a significant moderating relationship between EPS and deep white matter hyperintensities on visuospatial function score. Conclusions: EPS in AD are associated with severe cognitive impairment in attention and visuospatial function. Careful screening for EPS in patients with AD may assist in prediction of cognitive profile.