Change in Cognitive Performance From Midlife Into Old Age: Findings from the Midlife in the United States (MIDUS) Study

Abstract

Objective A substantial body of research has documented age-related declines in cognitive abilities among adults over 60, yet there is much less known about changes in cognitive abilities during midlife. The goal was to examine longitudinal changes in multiple cognitive domains from early midlife through old age in a large national sample, the Midlife in the United States (MIDUS) study. Method The Brief Test of Adult Cognition by Telephone (BTACT) was administered on two occasions (MIDUS 2, MIDUS 3), an average of 9 years apart. At MIDUS 3, those with the cognitive assessment (N = 2,518) ranged in age from 42 to 92 years (M = 64.30, SD = 11.20) and had a mean education of 14.68 years (SD = 2.63). The BTACT includes assessment of key aging-sensitive cognitive domains: immediate and delayed free recall, number series, category fluency, backward digit span, processing speed, and reaction time for attention switching and inhibitory control, which comprise two factors: episodic memory and executive functioning. Results As predicted, all cognitive subtests and factors showed very small but significant declines over 9 years, with differences in the timing and extent of change. Processing speed showed the earliest and steepest decrements. Those with higher educational attainment scored better on all tests except reaction time. Men had better executive functioning and women performed better on episodic memory. Conclusions Examining cognitive changes in midlife provides opportunities for early detection of cognitive impairments and possibilities for preventative interventions.

Longitudinal Characterization and Biomarkers of Age and Sex Differences in the Decline of Spatial Memory

“…Longitudinal studies that address sex differences in older humans generally indicate poorer episodic memory in men. There is a debate concerning sex differences in the trajectory of cognitive impairments, with results indicating no difference or a steeper decline in males (Finkel et al, 2003;Ferreira et al, 2014;Lundervold et al, 2014;McCarrey et al, 2016;Olaya et al, 2017;Hughes et al, 2018;Lee et al, 2018;Casaletto et al, 2019). Cross-sectional rodent studies indicate age and sex differences in tasks that involve repeated acquisition of spatial information and episodic memory (Lukoyanov et al, 1999;Markowska, 1999;Rossetti et al, 2018); nevertheless, most longitudinal studies in animal models of aging have not compared sex differences in the decline of memory.…”

Supplemental Material for Risk of Cognitive Declines With Retirement: Who Declines and Why?

“…Several precautions were taken to ensure our samples of middle-aged and older adults who retired versus remained employed were directly comparable. This was accomplished by (a) selecting individuals who were working at baseline and who either retired or remained employed nine years later and (b) using propensity score matching to equate participants on central demographic and health variables linked to cognitive functioning: age, gender, education, income, occupation, and health status (Hughes et al, 2018;Lachman et al, 2014;. We adopted propensity score matching over alternative procedures because this approach has been shown to improve balance on influential covariates and thereby reduce bias in parameter estimates of sample differences (Austin, 2011;West et al, 2014).…”

“…Empirically, past studies have shown that episodic memory and executive functioning typically ONLINE SUPPLEMENTAL MATERIALS 4 begin to decline more rapidly in midlife after age 50 (Hughes et al, 2018;Lachman et al, 2014).…”

“…Measures of episodic memory and executive functioning factors were calculated by averaging the standardized values of their respective subtests (Hughes et al, 2018). Episodic memory was thus comprised of the standardized average of the immediate and delayed recall tests.…”

A cross-sectional study on interference control: age affects reactive control but not proactive control

“…For example, content-context binding (Cowan et al, 2006;Hommel, Kray & Lindenberger, 2011;Siegel, 1994;Swanson, 2017) and switch (Kray, Eber & Lindenberger, 2004;Reimers & Maylor, 2005) decrease approximately linearly across the adult life-span. The decline of memory, process speed, inhibition and reasoning begin from middle age (Anstey et al, 2015;Borella, Carretti & De Beni, 2008;Davis et al, 2017;Hughes et al, 2018;Persad et al, 2002;Singh-Manoux et al, 2012;Zimprich & Mascherek, 2010). Although the timing of age-related decline of cognitive functions varies, middle age looks like an important age boundary.…”