Table 1.

List of measures and how they were defined as external validators of the nine-class solutions

External validators	Definition
Demographics
Ethnicity	We categorized race into Non-Hispanic White, African American, and Other, which included Hispanics, Asians, and others.
WRATa	Administered during the clinical interview as a measure for premorbid IQ. Assessed on a continuous scale.
BIMCb	Administered during the clinical interview as a measure of global cognitive function. Assessed on a continuous scale.
Physical function
Gait speed	Continuous measure assessing the time taken (in seconds) to walk 20 feet, turn, and return (40 feet total) at the subject’s normal walking pace on a 12 foot instrumented walkway.
Grip strength	Continuous measure of the maximum strength on 3 trials on the dominant hand using a grip dynamometer.
Peak Flow	Continuous measure of mean expiration of 3 trials of blowing into a peak flow meter.
Psychological well-being
Stress	Perceived Stress Scale (PSS-14, range 0–52) (Cohen, Kamarck, & Mermelstein, 1983); continuous scale with higher scores indicating more stress. We assessed the Distress and Coping components separately on a continuous scale with higher scores indicating more stress. The PSS-14 has been validated in our cohort (Ezzati et al., 2014) and applied using this approach in prior studies (Hewitt, Flett, & Mosher, 1992), including on our own dataset (Ezzati et al., 2014).
Depression	The Geriatrics Depression Scale - short form (Sheikh & Yesavage, 1986); continuous scale, with higher scores indicating more depression symptomatology.
Neuroticism	The International Personality Item Pool (IPIP) (Goldberg et al., 2006) was used to measure neuroticism.
Health and disease
Smoking	Ordinal: 1) Never; 2) past; 3) current
Diabetes (DM)	DM was defined according to the NCEP Adult Treatment Panel III (“Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III),” 2001) : Elevated fasting glucose at ≥ 100mg/dL. All participants with DM in the EAS were treated.
Hypertension (HTN)	HTN was defined according to the NCEP Adult Treatment Panel III (“Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III),” 2001):Systolic blood pressure ≥130mmHg diastolic BP ≥85 mmHg.We analyzed both treated and untreated HTN.
History of stroke	Collected from the medical history during the clinical interview.

^aWRAT = Wide Range Achievement Test - we used this as a marker of premorbid IQ (Franzen, Burgess, & Smith-Seemiller, 1997).

^bBIMC= Blessed Information Memory Concentration Test (Katzman et al., 1983).