Race moderates the association of perceived everyday discrimination and hair cortisol concentration

Figures & data

Figure 1. Bar graphs depicting the distribution of perceived discrimination attributions by race. Only participants reporting perceived discrimination at least "a few times a year" or more were asked to report attributions (N = 80). Race/Ances: Race/Ancestry; Physical App: Physical Appearance; Educ/Income: Education/Income; Sexual Orient: Sexual Orientation. **p < 0.01; ***p < 0.001.

Table 1. Descriptive information of the study sample.

	Full sample (N = 141)	White (n = 72)	African American (n = 69)	t or χ^2
Age, years	45.77 (15.17)	42.35 (15.04)	49.33 (14.58)	−2.80**
Sex, n female (%)	95 (67)	41 (57)	54 (78)	7.28**
Annual household income, n ≥ $40,000/year (%)	77 (55)	48 (67)	29 (42)	8.63**
Hair washes/week	3.10 (2.27)	4.60 (2.01)	1.54 (1.24)	10.91***
Hair treatment use
Conditioner, n yes (%)	112 (79)	51 (71)	61 (88)	6.66*
Bleach, n yes (%)	19 (14)	8 (11)	11 (16)	0.71
Permanent Wave, n yes (%)	23 (16)	1 (1)	22 (32)	24.00***
Straightening, n yes (%)	34 (24)	5 (7)	29 (42)	24.70***
Days of ≥30 min physical activity/week	3.48 (2.09)	4.13 (1.92)	2.81 (2.06)	3.92***
Waist-to-hip ratio	0.88 (0.09)	0.87 (0.08)	0.89 (0.09)	−1.33
Emotional stability	5.20 (1.32)	5.20 (1.21)	5.19 (1.43)	0.06
Perceived stress	1.21 (0.72)	1.17 (0.71)	1.26 (0.75)	−0.80
Perceived everyday discrimination	10.06 (4.38)	9.54 (3.22)	10.61 (5.29)	−1.44
Hair cortisol concentration, pg/mg, median (IQR)	7.7 (16.6)	6.0 (7.2)	8.6 (21.2)	−2.27*

IQR: interquartile range.

All data provided as mean (standard deviation) unless indicated otherwise. Group comparisons were performed using t-tests for continuous variables and Pearson chi-square tests for categorical variables.

*p < 0.05; **p < 0.01; ***p < 0.001.

Table 2. Bivariate correlations among variables involved in inferential analyses (N = 141).

	1	2	3	4	5	6	7	8	9
1. Age	–
2. Sex	.17*	–
3. Race	.23**	.23*	–
4. Annual household income	.22*	−.05	−.24**	–
5. Physical activity	−.13	−.09	−.32***	.15	–
6. WHR	.36***	−.24**	.11	−.08	−.09	–
7. Emotional stability	.03	−.07	.00	.25**	.16	.02	–
8. Perceived stress	−.13	.04	.07	−.29***	−.15	.03	−.38***	–
9. Perceived discrimination	−.12	−.06	.12	−.21*	−.20*	.01	−.31**	.45***	–
10. Log-HCC	.20*	−.07	.19*	−.11	.07	.25**	−.04	.05	.15

Sex (Male = 0, Female = 1); Race (White = 0, African American = 1). WHR: waist-to-hip ratio.

*p < 0.05; **p < 0.01; ***p < .001.

Figure 2. Simple slopes depicting the association between perceived everyday discrimination and hair cortisol concentration for White and African American participants (N = 141). **p < 0.01.

Table 3. Standardized coefficients from regression models predicting log-hair cortisol concentration (N = 141).

	Step 1		Step 2		Step 3		Step 4
	β	p Value	β	p Value	β	p Value	β	p Value
Age	0.21*	0.024	0.17^†	0.073	0.18^†	0.051	0.15^†	0.097
Sex	−0.07	0.448	−0.10	0.256	−0.08	0.360	−0.03	0.781
Annual household income	−0.15	0.069	−0.10	0.246	−0.09	0.254	−0.09	0.275
Physical activity	0.14	0.113	0.19*	0.040	0.20*	0.020	0.19*	0.029
WHR	0.16^†	0.052	0.16^†	0.059	0.16^†	0.053	0.21**	0.009
Emotional stability	−0.03	0.774	−0.05	0.604	−0.02	0.823	0.01	0.907
Perceived stress	0.04	0.693	0.04	0.704	−0.02	0.817	−0.01	0.898
Race			0.19*	0.030	0.17^†	0.054	−0.29^†	0.172
Perceived discrimination					0.17*	0.045	−0.11	0.283
Race × Discrimination							0.59**	0.007
Model R^2	0.115		0.142		0.163		0.189
F for R^2 change	3.03*	0.022	4.22*	0.030	3.20*	0.045	4.35**	0.007

Sex (Male = 0, Female = 1); Race (White = 0, African American = 1). WHR: waist-to-hip ratio.

^†p < 0.10; *p < 0.05; **p < 0.01.