Minor neuropsychological deficits in patients with subjective cognitive decline

Objective: To determine the nature and extent of minor neuropsychological
deficits in patients with subjective cognitive decline (SCD) and their
association with cerebrospinal fluid (CSF) biomarkers of Alzheimer’s
disease (AD). Method: We analyzed data from n=449 cognitively normal
participants (n=209 healthy controls, n=240 SCD patients) from an interim
data release of the German Center for Neurodegenerative Diseases
Longitudinal Cognitive Impairment and Dementia Study (DELCODE). An
extensive neuropsychological test battery was applied at baseline for
which we established a latent, five cognitive domain factor structure
comprising learning & memory, executive functions, language
abilities, working memory and visuospatial functions. We compared groups
regarding global and domain-specific performance and correlated
performance with different CSF markers of AD pathology. Results: We
observed worse performance (Cohen’s d≈0.25-0.5, adjusted for age-, sex
differences with ANCOVA) in global performance, memory, executive
functions and language abilities for the SCD group compared to healthy
controls. In addition, worse performance in these domains was moderately
(r≈0.3) associated with lower CSF-Aβ42/40 and CSF-Aβ42/ptau181 in the
whole sample and specifically in the SCD subgroup. Conclusions: Within the
spectrum of clinically unimpaired (i.e., “pre- mild cognitive impairment”)
cognitive performance, SCD is associated with minor deficits in memory,
executive function and language abilities. The association of these subtle
cognitive deficits with AD CSF biomarkers speaks to their validity and
potential use for the early detection of underlying preclinical AD.