Challenges in the development of accurate normative neuropsychological test data for older adults: Findings from the HELIAD Study: Neuropsychology/early detection of cognitive decline with neuropsychological tests

Background Normative data collected from older adult cohorts may be tainted by the inadvertent inclusion of undiagnosed individuals at the very early stage of a dementia process or Mild Cognitive Impairment (MCI). To avoid this pitfall, we developed normative data from an older adult group who remained cognitively intact at follow‐up examination. The present work addresses the challenge and the absence of appropriate normative data for a range of neuropsychological tests in older adults in Greece. Method 1031 community dwelling participants (age≥65) underwent neurological and neuropsychological assessment on two occasions with a mean interval of 2.8 years (range:1.2‐5.2; SD:0.8) for the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD). A value of 0 or 0.5 for the Clinical Dementia Rating (CDR) and a threshold value of ≥ 26 on the Mini Mental State Examination (MMSE) were used as clinical diagnostic criteria to determine the cognitive status of the participants. Based on these criteria, 750 individuals were cognitively intact in both evaluations and their data were used for norms development. Participants received a comprehensive neuropsychological assessment encompassing five cognitive domains: memory, language, attention/speed, executive and visual‐spatial functioning. Multiple linear regression models were performed, with age at baseline (years), education (years) and sex as the demographic predictors for regression‐based normative formulae, and raw test scores as the dependent variables. The effects of age, education and sex were investigated for each test and subtest separately. Discrete norms were also derived, stratified by four age strata (64‐69, 70‐74, 75‐79, 80‐89) and by three education strata (0, 1‐9, 10+). Result Regression analyses revealed that education was associated with all test scores, whereas age was an important predictor of all but a few visuoperceptual, executive functioning and memory variables. Women outperformed men on verbal memory, attention/information processing speed and subtests of executive functioning. Men, however, outperformed women on visual memory recall and visuospatial perception. Conclusion The current study provides sound normative data for widely‐used neuropsychological tests among older adults, untainted by potential early and undiagnosed cognitive impairment. We report both discrete and regression‐based norms for use in clinical settings to identify cognitive decline in older adults.