Regression-based cognitive change norms applied in biochemically defined predementia Alzheimer's disease.

OBJECTIVE

We aim to develop 2-year cognitive change norms for adults ages 41-84 for six cognitive tests, and to evaluate these norms in groups with AD biomarkers.

BACKGROUND

Practice effects are common in repeated neuropsychological testing. Not accounting for practice effects may obscure cognitive decline in early Alzheimer's disease (AD).

METHOD: We developed standardized regression-based change norms from normative samples consisting of healthy controls from the Dementia Disease Initiation study (n = 125), the Trønderbrain study (n = 57), and the Gothenburg mild cognitive impairment (MCI) study (n = 65). Norms were applied in a sample with cognitive symptoms (subjective cognitive decline or MCI) and AD cerebrospinal fluid (CSF) biomarkers (n = 246), classified according to the A/T/N system.

RESULTS

The change norms adjusted for pertinent demographics and practice effects. The group with cognitive complaints displayed a trend toward cognitive decline compared to the normative group, with the A +T/N + subgroup showing the most marked decline. This was observed in tests of episodic memory and cognitive flexibility/divided attention.

CONCLUSIONS

We present 2-year cognitive change norms for adults between 41 and 84 years, adjusted for practice and demographics. A web-based change norm calculator is provided. (PsycInfo Database Record (c) 2023 APA, all rights reserved).