Table 1. Description of Measures of Aging in Midlife and Matched Measures of Health in Childhood.

Outcome	Type of measure	Descriptiona	Ages, y
Pace of aging	Laboratory test	Participants’ pace of biological aging across ages 26-45 y was measured as changes in 19 biomarkers of cohort members’ cardiovascular, metabolic, pulmonary, kidney, immune, and dental systems across ages 26, 32, 38, and 45 y. The measure quantifies participants’ rate of aging in year-equivalent units of physiological decline per chronological year. The average participant experienced 1 y of physiological decline per year, a mean (SD) pace of aging of 1 (0.3).13	26-45
	Self-report	Participants’ self-perceived age at age 45 y was measured using participants’ response to the question, “Many people feel younger or older than they really are. What age do you feel most of the time?” The mean (SD) self-perceived age in participants aged 45 y was 40 (8) years.	45
	Matched childhood measure	Participants’ childhood physical health between birth and age 11 was measured using birth records, medical exams, anthropometry, lung function testing, nurse ratings, and interviews with parents about health conditions (eg, asthma, childhood diabetes).22	Birth, 3, 5, 7, 9, 11
Hearing	Laboratory test	Participants’ social hearing (ability to hear in noisy environments) at age 45 y was measured using the Listening in Spatialised Noise–Sentences Test (LISN-S). The test determines speech reception thresholds for sentences presented in competing speech under various conditions. For our primary analyses, we used a measure of low cue speech reception threshold, reflecting hearing performance when the person is not receiving optimum auditory information.23	45
	Self-report	Participants’ hearing difficulties at age 45 y were measured using 3 items from the Speech, Spatial, and Qualities of Hearing Scale (SSQ12) (eg, “Can you follow the conversation in a busy restaurant?”).24	45
	Matched childhood measure	Participants’ childhood social hearing at age 11 was assessed using a speech-in-noise test. The test measures children’s ability to correctly identify words under conditions of no noise, 10-, and 5-dB signal-to-noise ratio. To match the childhood measure to the adult hearing measure, we used children’s performance in the 5-dB signal-to-noise ratio condition, reflecting social hearing ability in the most difficult auditory environment.25	11
Vision	Laboratory test	Participants’ contrast sensitivity at age 45 y was measured using a Pelli-Robson chart administered by trained technicians. The chart presents 3 letters per line and the letters gradually fade from black to gray to white on a white background to determine the lowest level of “contrast” that the eye can detect. The resulting measure is a contrast sensitivity score function, reflecting a person’s best-corrected contrast detection threshold, the lowest contrast at which a pattern can be seen.	45
	Self-report	Participants’ vision difficulties at age 45 y were assessed using the 10-item Vision Quality of Life Core Measure (VCM1) questionnaire (eg, “How often has your eyesight stopped you from doing the things you wanted to do?”).26	45
	Matched childhood measure	Participants’ childhood vision was assessed at ages 7, 9, and 11 y using the Sheridan Gardiner single optotype letter matching test at 6 m (at age 7 y) and a 4-m logarithmic test chart (at ages 9 and 11 y).27	7, 9, 11
Balance	Laboratory test	Participants’ balance at age 45 y was measured using the Unipedal Stance Test, as the maximum time achieved across 3 trials of the test with eyes closed.28	45
	Self-report	Participants’ balance difficulties at age 45 y were measured using 4 items (eg, “Do you have feelings that things are spinning or moving around?”).	45
	Matched childhood measure	Participants’ childhood balance at ages 3, 7, and 9 y was measured using the balance subtests of the Bayley Motor Scales (age 3 y) and of the Basic Motor Ability Test (ages 7 and 9 y).29,30	3, 7, 9
Motor function	Laboratory test	Participants’ gait speed (m/s) at age 45 y was measured using the GAITRite Electronic Walkway (CIR Systems Inc). Gait speed was assessed under 3 conditions: usual gait speed (walk at normal pace; mean of 2 walks) and 2 challenge paradigms, dual task gait speed (walk at normal pace while reciting alternate letters of the alphabet out loud; mean of 2 walks), and maximum gait speed (walk as fast as safely possible; mean of 3 walks). We calculated the mean of the 3 individual walk conditions to generate a measure of composite gait speed.13	45
	Self-report	Participants’ physical function at age 45 y was assessed using the 10-item RAND 36-Item Health Survey 1.0 physical functioning scale, with reversed scores to reflect limitations.31	45
	Matched childhood measure	Participants’ childhood motor development at ages 3, 5, 7, and 9 y was measured using the Bayley Motor Scales (age 3 y), McCarthy Motor Scales (age 5 y) and Basic Motor Ability Test (ages 7 and 9 y).29,30,32	3, 5, 7, 9
Cognitive function	Laboratory test	Participants’ cognitive ability at age 45 y was measured using the Wechsler Adult Intelligence Scale–IV (WAIS-IV), individually administered.33	45
	Self-report	Participants’ cognitive complaints at age 45 y were measured using 23 items mapping onto DSM-5 symptoms of mild neurocognitive disorder and items from the Cognitive Failures Questionnaire (CFQ), eg, “I have difficulty finding the word I want to use”; “I repeat myself, I tell the same story to the same person”; “I forget why I went from one part of the house to the other.”34,35	45
	Matched childhood measure	Participants’ childhood cognitive ability at ages 7, 9, and 11 y was measured using the Wechsler Intelligence Scale for Children – Revised (WISC-R), individually administered at each age. IQ scores for the 3 ages were averaged.36	7, 9, 11

^aMore information is available in eAppendix 3 in the Supplement.