Abstract
Subjective and objective cognitive declines are given equal weight as symptoms of pre-mild cognitive impairment in Alzheimer’s disease by recent research criteria. However, the overlap of these constructs is unclear. We used standardized regression-based (SRB) change to define subtle objective cognitive decline across serial neuropsychological assessments. We then examined the associations between objective change and subjective cognitive complaints. Finally, we investigated the impact of different symptom combinations on rates of classification for the early stages of the Alzheimer’s Continuum.
Data from 1,341 cognitively intact older adults with serial Uniform Data Set 3.0 Neuropsychological Battery assessments (6–24-month follow-ups) were used to compute SRB declines at the following z-scores cut-points: −1.282, −1.645, and − 1.96. We used Chi-square tests and Cohen’s kappa statistics to evaluate the relationship between SRB change and presence/absence of subjective cognitive decline at follow-up. We also examined the prevalence rates of different symptom combinations in an amyloid positive sample (n = 29).
The base rate of having at least one significant SRB decline ranged from 26.00% to 59.40%. Subjective cognitive decline was positively associated with SRB-defined decline in the normative sample, though agreement was limited (= − .01–.10). SRB decline with no subjective decline occurred in 0.0–37.90% of amyloid positive participants, while 3.40–37.90% had subjective but not objective decline. 37.90–79.30% of amyloid positive participants exhibited either SRB or subjective decline.
Subjective and objective cognitive declines appear to represent unique symptom classes and should be separately considered when staging patients on the Alzheimer’s Continuum.
