Description of Alternative Explanatory Variables That May Explain the Association Between Perinatal Complications and Aging Indicators at 38 y

Alternative Explanatory VariableDescriptionAssessment AgesPerinatal Complications (Mean, SD)
Family histories of medical problemsIn 2003–2006, we interviewed study members and their biological parents to obtain histories of medical problems about study members’ first- and second-degree relatives.54 The following conditions were assessed: heart disease (defined as a history of heart attack, balloon angioplasty, coronary bypass, or angina), stroke, high blood pressure, high cholesterol, diabetes, asthma, and cancer. We created the family history score indicating medical problems by calculating the proportion of a study member’s extended family with a positive history of any medical problem.Lifetime0 (3.87, 1.13)
1 (3.72, 1.07)
≥2 (3.66, 1.13)
Childhood social adversityThe SES of study members’ families was measured with a 6-point scale assessing parents’ occupational status. The scale places each occupation into 1 of 6 categories (from 1, unskilled laborer to 6, professional) on the basis of education levels and income associated with that occupation in data from the New Zealand census. Family SES was the average of the highest SES level of either parent from birth through age 15 y. This variable reflects the socioeconomic conditions experienced by the participants while they were growing up.Birth to 11 y0 (1.08, 0.50)
1 (1.12, 0.48)
≥2 (1.15, 0.51)
Cognitive healthIntelligence tests were administered in childhood at ages 7, 9, 11, and 13 y and again in adulthood at age 38 y. We used the Wechsler Intelligence Scale for Children–Revised55 and the Wechsler Adult Intelligence Scale, Fourth Edition.56 These tests comprise a series of subtests that yield indices standardized to population norms (M = 100, SD = 15). To derive a measure of life course cognitive health, we created an average IQ score by using data from 7 to 38 y.7–38 y0 (101.41, 13.73)
1 (99.49, 13.81)
≥2 (96.57, 14.28)
Mental healthPsychiatric disorders (according to the Diagnostic and Statistical Manual of the American Psychiatric Association) were assessed among study members via private structured interviews using the Diagnostic Interview Schedule at ages 18, 21, 26, 32, and 38 y. We repeatedly assessed the following disorders by using 1-year reporting periods: alcohol dependence, cannabis dependence, dependence on hard drugs, tobacco dependence (assessed with the Fagerstrom Test for Nicotine Dependence),57 conduct disorder, major depression, generalized anxiety disorder, fears and phobias, obsessive–compulsive disorder, mania, and schizophrenia. As previously described,58 we carried out confirmatory factor analyses of these psychiatric disorders, taking into account their persistence, co-occurrence, and sequential comorbidity, from ages 18–38 y. The structure of mental disorders could be summarized by 3 core psychopathological dimensions: an internalizing liability to depression and anxiety, an externalizing liability to antisocial and substance use disorders, and a thought disorder liability to symptoms of psychosis. At a higher-order level, we showed that these liabilities themselves reflected 1 general underlying dimension that summarized subjects’ propensity to develop any form of common psychiatric and substance use disorders.58 Higher scores on this dimension index persistent and impairing mental illness.18–38 y0 (98.24, 13.93)
1 (101.14, 15.51)
≥2 (99.14, 15.24)
Vascular healthBlood pressure at ages 26, 32, and 38 y was assessed according to standard protocols59 using a Hawksley random-zero sphygmomanometer (Hawksley & Sons Ltd, Lancing, UK) with a constant deflation valve. Systolic and diastolic blood pressures were combined to derive a measure of mean arterial pressure: [(2 × diastolic) + systolic]/3. To derive a measure of vascular health, we averaged all 3 mean arterial pressure variables at 26, 32, and 38 y.26–38 y0 (89.41, 7.69)
1 (90.25, 7.63)
≥2 (89.76, 7.25)
Physical healthPhysical health at ages 26, 32, and 38 y was measured by clinical indicators of poor adult health, including metabolic abnormalities (waist circumference, high-density lipoprotein level, triglyceride level, blood pressure, and glycated hemoglobin), poor cardiorespiratory fitness, poor pulmonary function, periodontal disease, and systemic inflammation (high-sensitivity C-reactive protein) (Supplemental Table 3). Pregnant women were excluded from the reported analyses. We summed the number of clinical indicators on which study members exceeded clinical cutoffs at each age. To derive a measure of physical health, we averaged all 3 physical health indexes at 26, 32, and 38 y. (Blood pressure duplicates vascular health, but we retained it in the physical health index because it is a standard constituent of a clinical physical health examination).26–38 y0 (1.37, 1.05)
1 (1.56, 1.12)
≥2 (1.34, 1.00)