Cognitive Correlates of the No Practice Effects (NPE) Battery: Factor Analyses from the Novel Cognitive and Functional Measures for Alzheimer’s Disease Prevention Trials (NoMAD)

Abstract

AbstractBackgroundThe No Practice Effects (NPE) battery is a novel set of neuropsychological measures designed to assess important cognitive domains and have robust psychometric properties for use in preclinical and early‐stage Alzheimer’s disease clinical trials. The current study used exploratory factor analysis to examine cognitive domains in the NPE battery. We further examined the association between identified cognitive domains with demographic characteristics, brain imaging metrics, and genetic risk markers for Alzheimer’s disease.MethodsA total of 116 older adults who are cognitively healthy or have early mild cognitive impairment (eMCI) (mean age 70.35 ± 6.53, 62.9% women) and have baseline cognitive assessments were included. The NPE battery contains seven primarily computerized tests of memory and attention. We conducted an exploratory factor analysis using an oblique rotation to identify different cognitive domains within the NPE, then composite scores were calculated for each domain. Simple correlation analyses were conducted to examine the association between these composite scores and demographic characteristics. The multiple regression analyses were performed to examine the association between composite scores and AD risk markers.ResultsThe exploratory factor analysis produced three factors within the NPE battery corresponding to 1) Cognitive Control/Executive Functions (including Letter and Category Verbal Fluency, Brown‐Peterson Paradigm, Digit Symbol Substitution Test, Letter‐Number Span, and N‐Back); 2) Response Monitoring (Recognition Memory Test [RMT] learning and correctly rejected recognition items) reflecting encoding process and post‐recollection cognitive monitoring; and 3) Recall/Retention (RMT total recall and hits on recognition items) that may be considered a “memory consolidation” factor. Greater performance on Response Monitoring was associated with younger age (r2 = ‐0.27, P = 0.004), higher education level (r2 = 0.29, P = 0.002), and APOE4 genotype (B = ‐0.27, SE = 0.13, P = 0.04). Recall/Retention was positively associated with the thickness of the entorhinal cortex (B = 0.58, SE = 0.28, P = 0.04), but not hippocampal or parahippocampal volumes. The general composite score encompassing all tests was associated with age (r2 = ‐0.29, P = 0.002), education (0.28, P = 0.003), and APOE4 (B = ‐0.25, SE = 0.10, P = 0.01).ConclusionThese results provide preliminary evidence that the NPE battery identifies domains characteristic of cognition. These cognitive domains were associated with demographic factors, such as age and education, along with APOE4 genotype, and brain structural measures.