Sociodemographic patterns in biomarkers of aging in the Add Health cohort

Figures & data

Table 1. Weighted descriptive statistics for study sample, Add Health Wave V biosample (N = 4713).

Sample Characteristics	N or mean	% or range
Age (years)	38.3	(33.0–44.8)
Sex Assigned at Birth
Female	2822	50.4%
Male	1891	49.6%
Self-Selected Race/Ethnicity
Asian	221	2.4%
American Indian/Alaska Native	32	0.8%
Black, African American	887	17.0%
Hispanic	484	8.6%
Pacific Islander	26	0.2%
Some other race or origin	16	0.4%
White	3047	70.5%
Nativity
Foreign Born	229	4.2%
Native Born	4484	95.8%
Educational Attainment
HS/GED or less	709	17.8%
Some College/Technical Training	1818	40.7%
College Degree or higher	2186	41.5%
Total Household Income
<$25,000	658	15.6%
$25,000–$49,999	828	18.5%
$50,000–$99,999	1552	33.5%
≥$100,000	1636	32.4%
Missing	39
Current Region
West	1076	18.0%
Midwest	1214	30.6%
Northeast	472	9.6%
South	1773	41.7%
Missing	178
BMI
Normal	1196	24.0%
Overweight	1350	29.1%
Obese	2166	46.9%
Missing	1
Smoking Status
Never Smoker	2756	53.3%
Past Smoker	919	22.1%
Current Smoker	1035	24.7%
Missing	3

Statistics are mean, (range) for continuous variables and N, % for categorical.

Table 2. Weighted distributions of inflammatory and neurodegenerative biomarkers, Add Health Wave V biosample (N = 4713).

Biomarker (units)	N	Mean, (SE of Mean)		Median	5th Percentile	25th Percentile	75th Percentile	Range	% Below the LOD	% Extrapolated by LCBR^1
IL-10 (pg/mL)	4712	0.35,	(0.01)	0.24	0.11	0.17	0.35	(0.02–57.92)	0.01%	0.16%
IL-1β (pg/mL)^2	3221	0.02,	(0.001)	0.02	0.004	0.005	0.06	(0.001–403.81)	31.0%	3.82%
IL-6 (pg/mL)	4707	1.79,	(0.54)	0.66	0.24	0.42	1.09	(0.02–1273.58)	0.22%	0.09%
IL-8 (pg/mL)	4713	54.21,	(6.85)	13.33	6.21	9.77	22.01	(2.43–3418.95)	0%	0.83%^3
IL-6/IL-10 (pg/mL)	4706	4.43,	(0.26)	2.67	0.73	1.57	4.73	(0.01–577.11)	N/A	N/A
TNF- α (pg/mL)	4711	2.81,	(0.10)	2.49	1.28	1.99	3.03	(0.13–2954.57)	0.06%	0.003%^3
hsCRP (mg/L)	4502	3.83,	(0.13)	1.75	0.24	0.78	4.43	(0.15–88.20)	3.6%	0.11%
NFL (pg/mL)	4708	7.46,	(0.16)	6.19	3.29	4.72	8.28	(0.74–235.23)	0.07%	0%
Total Tau (pg/mL)	4666	2.66,	(0.10)	2.26	0.56	1.52	3.03	(0.05–769.95)	0%	1.9%^4

¹Data reduction software at Laboratory for Clinical Biochemistry Research (LCBR) extrapolated values for some data points beyond the detectable range of the standard curve. Extrapolated values were below the Limit of Detection (LOD) unless indicated.

²Mean (SE) estimated using Tobit regression analyses to account for large proportion of left-censoring. Distributional values were approximated by imputing LOD/2 for censored values.

³Observations were above the LOD.

⁴There were observations both below and above the LOD. About 1.9% were below and extrapolated, and two observations were above.

Table 3. Weighted, log-transformed means and standard errors of inflammatory biomarkers by sociodemographic variables, Add Health Wave V biosample(N = 4713).

			ln(IL-1β) N = 3221				ln(IL-8) N = 4713				ln(IL-6/IL-10) N = 4706				ln(TNF-α) N = 4711				ln(hsCRP)^2 N = 4502
Sociodemographic Variable			Mean	(95% CI)		p-value^3	Mean	(95% CI)		p-value^4	Mean	(95% CI)		p-value^4	Mean,	(95% CI)		p-value^4	Mean	(95% CI)		p-value^4
Age Categories
		≤median age (38.2 years)	−3.71	(−3.84,	−3.58)	0.0002	2.94	(2.87,	3.02)	<.0001	0.97	(0.90,	1.03)	0.002	0.90	(0.87,	0.94)	0.20	0.66	(0.58,	0.74)	0.04
		>median age	−4.06	(−4.22,	−3.91)		2.80	(2.73,	2.87)		1.05	(1.00,	1.10)		0.89	(0.87,	0.91)		0.59	(0.51,	0.66)
Biological Sex
	Male		−3.90	(−4.04,	−3.76)	0.95	2.88	(2.81,	2.96)	0.30	0.96	(0.91,	1.01)	0.0001	0.95	(0.93,	0.98)	<0.0001	0.41	(0.34,	0.48)	<0.0001
	Female		−3.90	(−4.02,	−3.77)		2.85	(2.78,	2.92)		1.06	(1.00,	1.13)		0.84	(0.82,	0.87)		0.83	(0.75,	0.91)
Self-Selected Race/Ethnicity
	Asian		−4.05	(−4.56,	−3.54)	0.67	2.59	(2.45,	2.73)	0.02	0.85	(0.68,	1.01)	<0.0001	0.79	(0.74,	0.85)	<0.0001	0.02	(−0.31,	0.34)	<0.0001
	Black		−3.79	(−4.00,	−3.58)		2.85	(2.75,	2.96)		1.23	(1.14,	1.33)		0.85	(0.81,	0.88)		0.85	(0.72,	0.97)
	Hispanic		−3.92	(−4.20,	−3.65)		2.84	(2.70,	2.97)		1.07	(0.95,	1.19)		0.88	(0.82,	0.95)		0.61	(0.46,	0.75)
	White		−3.93	(−4.07,	−3.78)		2.88	(2.81,	2.96)		0.95	(0.89,	1.01)		0.91	(0.89,	0.94)		0.58	(0.51,	0.65)
Nativity
		Foreign Born	−4.05	(−4.49,	−3.61)	0.49	2.69	(2.54,	2.83)	0.01	0.99	(0.79,	1.20)	0.77	0.87	(0.80,	0.94)	0.41	0.36	(0.05,	0.67)	0.003
		Native Born	−3.89	(−4.01,	−3.77)		2.87	(2.81,	2.93)		1.01	(0.96,	1.06)		0.90	(0.88,	0.92)		0.63	(0.57,	0.69)
Education
	College Degree or Higher		−3.99	(−4.13,	−3.85)	0.06	2.86	(2.78,	2.95)	0.91	0.83	(0.77,	0.89)	<0.0001	0.86	(0.84,	0.89)	<0.0001	0.43	(0.35,	0.51)	<0.0001
	Some College/Technical Training		−3.88	(−4.06,	−3.71)		2.86	(2.78,	2.94)		1.08	(1.02,	1.14)		0.90	(0.87,	0.93)		0.69	(0.61,	0.77)
	HS/GED or lower		−3.72	(−3.91,	−3.53)		2.88	(2.78,	2.98)		1.27	(1.18,	1.36)		0.96	(0.92,	0.99)		0.88	(0.77,	0.99)
Total Household Income
	<$25,000		−3.73	(−3.91,	−3.56)	0.08	2.83	(2.74,	2.92)	0.15	1.26	(1.17,	1.36)	<0.0001	0.98	(0.94,	1.02)	<0.0001	0.97	(0.84,	1.09)	<0.0001
	$25,000–$49,999		−3.86	(−4.09,	−3.63)		2.90	(2.79,	3.01)		1.15	(1.08,	1.22)		0.92	(0.88,	0.96)		0.80	(0.68,	0.92)
	$50,000–$99,999		−3.89	(−4.05,	−3.73)		2.89	(2.81,	2.97)		1.01	(0.93,	1.08)		0.90	(0.87,	0.93)		0.66	(0.57,	0.74)
	≥$100,000		−4.02	(−4.16,	−3.87)		2.82	(2.73,	2.92)		0.81	(0.76,	0.87)		0.84	(0.81,	0.87)		0.29	(0.20,	0.38)
Current Census Region
	Midwest		−3.94	(−4.24,	−3.64)	0.003	2.84	(2.69,	2.99)	0.0006	1.07	(0.98,	1.16)	<0.0001	0.94	(0.89,	0.98)	<0.0001	0.65	(0.53,	0.78)	0.0001
	Northeast		−3.83	(−4.13,	−3.52)		2.97	(2.85,	3.09)		0.88	(0.78,	0.97)		0.84	(0.79,	0.88)		0.54	(0.35,	0.73)
	South		−3.78	(−3.92,	−3.64)		2.90	(2.84,	2.97)		1.04	(0.98,	1.10)		0.89	(0.86,	0.92)		0.69	(0.62,	0.76)
	West		−4.19	(−4.36,	−4.01)		2.76	(2.66,	2.85)		0.89	(0.78,	0.99)		0.86	(0.83,	0.89)		0.47	(0.37,	0.57)
BMI Categories
	Normal		−3.96	(−4.16,	−3.75)	0.003	2.96	(2.86,	3.07)	0.0003	0.68	(0.60,	0.76)	<0.0001	0.85	(0.81,	0.88)	<0.0001	−0.16	(−0.26,	−0.06)	<0.0001
	Overweight		−4.05	(−4.22,	−3.88)		2.80	(2.73,	2.88)		0.84	(0.78,	0.91)		0.83	(0.80,	0.87)		0.30	(0.21,	0.39)
	Obese		−3.77	(−3.90,	−3.64)		2.85	(2.79,	2.92)		1.29	(1.24,	1.34)		0.96	(0.94,	0.99)		1.17	(1.11,	1.24)
Smoking Status
	Never Smoker		−4.01	(−4.14,	−3.89)	0.0003	2.83	(2.77,	2.89)	0.01	0.93	(0.86,	0.99)	<0.0001	0.87	(0.84,	0.89)	<0.0001	0.58	(0.50,	0.66)	<0.0001
	Past Smoker		−3.92	(−4.15,	−3.69)		2.90	(2.78,	3.01)		0.97	(0.91,	1.04)		0.91	(0.87,	0.94)		0.52	(0.42,	0.62)
	Current Smoker		−3.63	(−3.81,	−3.45)		2.92	(2.83,	3.01)		1.23	(1.16,	1.31)		0.95	(0.91,	0.99)		0.79	(0.70,	0.89)

¹All units in pg/mL unless otherwise indicated. P-values are from ANOVA for all biomarkers expect IL-1β. Tobit regressions were used for IL-1β to account for large proportion of left-censored values.

²units in mg/L.

Table 4. Weighted, log-transformed means and standard errors of neurodegenerative biomarkers by sociodemographic variables, Add Health Wave V biosample (N = 4713).

	ln(NFL)^1			ln(Tau)^1
	N = 4708			N = 4666
Sociodemographic Variable	Mean	(95% CI)	p-value^2	Mean,	(95% CI)	p-value^2
Age Categories
≤median age (38.2 years)	1.81	(1.78, 1.84)	<.0001	0.71	(0.67, 0.75)	0.55
>median age	1.91	(1.88, 1.93)		0.72	(0.68, 0.76)
Biological Sex
Male	1.86	(1.83, 1.89)	0.96	0.69	(0.65, 0.73)	0.01
Female	1.86	(1.84, 1.88)		0.74	(0.70, 0.78)
Self-selected Race/Ethnicity
Asian	1.86	(1.79, 1.94)	<0.0001	0.78	(0.62, 0.93)	0.0005
Black	1.79	(1.75, 1.84)		0.65	(0.59, 0.70)
Hispanic	1.76	(1.71, 1.81)		0.64	(0.55, 0.73)
White	1.89	(1.87, 1.91)		0.74	(0.70, 0.78)
Nativity
Foreign Born	1.76	(1.69, 1.84)	0.003	0.69	(0.56,0.83)	0.64
Native Born	1.86	(1.85, 1.88)		0.72	(0.69, 0.75)
Education
College Degree or Higher	1.86	(1.84, 1.89)	0.02	0.70	(0.65, 0.74)	0.35
Some College/Technical Training	1.84	(1.81, 1.88)		0.73	(0.69, 0.77)
HS/GED or lower	1.90	(1.85, 1.95)		0.73	(0.69, 0.78)
Household Annual Income
<$25,000	1.91	(1.84, 1.98)	0.004	0.78	(0.72, 0.85)	0.02
$25,000–$49,999	1.83	(1.79, 1.87)		0.73	(0.67, 0.79)
$50,000–$99,999	1.85	(1.82, 1.87)		0.70	(0.65, 0.75)
≥$100,000	1.86	(1.84, 1.89)		0.70	(0.65, 0.74)
Current Census Region
Midwest	1.88	(1.85, 1.92)	0.02	0.75	(0.69, 0.81)	0.001
Northeast	1.87	(1.82, 1.93)		0.63	(0.55, 0.71)
South	1.83	(1.80, 1.86)		0.72	(0.68, 0.77)
West	1.88	(1.84, 1.92)		0.66	(0.59, 0.73)
BMI Categories
Normal	2.04	(2.00, 2.08)	<0.0001	0.79	(0.74, 0.83)	<0.0001
Overweight	1.88	(1.85, 1.91)		0.67	(0.61, 0.72)
Obese	1.76	(1.74, 1.78)		0.71	(0.67, 0.75)
Smoking Status
Never Smoker	1.85	(1.82, 1.88)	<0.0001	0.67	(0.63, 0.71)	<0.0001
Past Smoker	1.82	(1.78, 1.86)		0.75	(0.68, 0.82)
Current Smoker	1.92	(1.88, 1.96)		0.78	(0.73, 0.84)

¹All units in pg/mL.

²p-value from ANOVA test.

Figure 1. Distribution of inflammatory and cognitive biomarkers by BMI categories, add health wave V biosample, N = 4713.