Table 1 Definitions of variables used

Wave 1 (2011–2012)

Time-invariant

 Age

Continuous

 Sex

Male = 1, female = 2

 BMI

Continuous

 Education level

11 Categories: “Illiterate,” “Did not finish primary school but capable of reading and/or writing,” “Home school,” “Elementary school,” “Middle school,” “High school,” “Vocational school,” and four higher levels

 Marital status

Living with spouse present = 1, married but not living with spouse temporarily for reasons such as work = 2, separated = 3, divorced = 4, widowed = 5, never married = 6

 Smoking

Yes = 1, no = 2

 Hukou status

Agricultural = 1, nonagricultural = 2

 Alcohol use

Drink more than once per month = 1, drink less than once per month = 2, none of these = 3

 Living status before age 16

Village = 1, city/town = 2

 Health status before age 16

Excellent = 1, very good = 2, good = 3, fair = 4, poor = 5

 Hypertension

Yes = 1, no = 2

 Diabetes or high blood sugar

Yes = 1, no = 2

 Psychiatric problems

Yes = 1, no = 2

 Memory-related disease

Yes = 1, no = 2

 Stroke

Yes = 1, no = 2

 Glucose

Continuous

 Glycosylated hemoglobin

Continuous

 Total cholesterol

Continuous

Time-variant

Waves 1–3 (2011–2016)

Continuous variable ranging from 0 to 21

 Pulse pressure

Continuous

 Systolic blood pressure

Continuous

 Diastolic blood pressure

Continuous

 ADL

Continuous variable ranging from 0 to 11

 Depression

Continuous variable ranging from 0 to 30