Normative Values of Cognitive and Physical Function in Older Adults: Findings from The Irish Longitudinal Study on Ageing

Objectives To provide normative values of tests of cognitive and physical function based on a large sample representative of the population of Ireland aged 50 and older. Design Data were used from the first wave of The Irish Longitudinal Study on Ageing (TILDA), a prospective cohort study that includes a comprehensive health assessment. Setting Health assessment was undertaken at one of two dedicated health assessment centers or in the study participant's home if travel was not practicable. Participants Five thousand eight hundred ninety-seven members of a nationally representative sample of the community-living population of Ireland aged 50 and older. Those with severe cognitive impairment, dementia, or Parkinson's disease were excluded. Measurements Measurements included height and weight, normal walking speed, Timed Up-and-Go, handgrip strength, Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Color Trails Test, and bone mineral density. Normative values were estimated using generalized additive models for location shape and scale (GAMLSS) and are presented as percentiles, means, and standard deviations. Results Generalized additive models for location shape and scale fit the observed data well for each measure, leading to reliable estimates of normative values. Performance on all tasks decreased with age. Educational attainment was a strong determinant of performance on all cognitive tests. Tests of walking speed were dependent on height. Distribution of body mass index did not change with age, owing to simultaneous declines in weight and height. Conclusion Normative values were found for tests of many aspects of cognitive and physical function based on a representative sample of the general older Irish population.