The Pace of Cognitive Aging in Older Adults Without a Neurocognitive Disorder

TL;DR

This study examines how memory declines with age in older adults without dementia, finding that the decline is minimal in the 70s but becomes more noticeable in the 80s and 90s.

Contribution

The study provides age-specific estimates of memory decline in older adults without dementia using a long-term cohort.

Findings

Memory decline is about -0.05 standard deviations per year in normative aging.

Age-specific estimates show -0.04 SD/y in the 70s, -0.10 SD/y in the 80s, and -0.15 SD/y in the 90s.

The decline becomes noticeable in the 80s and quite impairing in the 90s.

Abstract

The pace of cognitive change without a neurocognitive disorder is one of the major questions in cognitive aging. The Children of the Depression Age (CODA) cohort of the Health and Retirement Study (HRS) is ideal for studying cognitive aging because it has a long follow-up (22 years) and a narrow age range at baseline (67-74 years). We analyzed data on delayed word recall performance in HRS-CODA (N = 2,295), gathered every other year during the follow-up period. Using latent growth curve modeling and treating delayed recall as a categorical outcome, we found a quadratic model showed better fit to the data than a linear model, with no strong evidence for a practice and retest effect. When calculating the pace of normative aging, our results suggested normative (defined as the absence of a dementia diagnosis over the follow-up period) memory decline is about -0.05 standard deviations per year (SD/y), but is better characterized by age specific estimates of -0.04 SD/y, -0.10 SD/y, and -0.15 SD/y for individuals in their 70s, 80s, and 90s, respectively. These results would suggest that memory decline, in the absence of a recognized dementia and without a confounding of baseline age differences and longitudinal age changes, would be present but almost imperceptible to an individual in their eighth decade, but noticeable in their ninth and quite impairing in their tenth decade.