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.