Applied relaxation and cortisol secretion: findings from a randomized controlled indicated prevention trial in adults with stress, anxiety, or depressive symptoms

Figures & data

Table 1. Sample characteristics at pre-assessment for the analysis sample.

	Intervention group (N = 102)			Control group (N = 134)
	N	%/M	SD	N	%/M	SD	p*
Age (M/SD)	–	36.00	10.82	–	33.70	10.15	.123
Sex
Female	75	73.53	–	91	67.91	–	.349
Male	27	26.47	–	43	32.09	–	–
BMI	–	24.25	4.18	–	24.39	5.23	.540
Physically active, hours	–	2.91	2.80		2.45	2.35	.351
Oral contraceptives use	4	3.92	–	11	8.21	–	.181
School education
Low (8th grade)	1	0.98	–	1	0.75	–	.243
Middle (10th grade)	24	23.53	–	27	20.15	–	–
High (12th grade)	77	75.49	–	102	76.12	–	–
Other	0	0	–	4	2.99	–	–
Social class
Lowest/lower middle	17	16.67	–	29	21.65	–	.427
Middle	61	59.80	–	77	57.46	–	–
Upper middle/upper	24	23.53	–	28	23.14	–	–
Marital status
Married/registered partnership	41	40.20	–	45	33.59	–	.388
Divorced/separated/widowed	4	3.92	–	7	6.23	–	–
Never married	57	55.88	–	82	61.19	–	–
Citizenship
German	100	98.04	–	132	98.51	–	.782
Other	2	1.96	–	2	1.49	–	–

Data are percentages or means (SE).

*Statistical comparisons were performed with χ² test (nominal data) or Mann–Whitney-U-test (continuous data).

M: mean; SD: standard deviation; BMI: body mass index.

Table 2. Cortisol measures at pre-assessment, post-assessment, and follow-up.

	Analysis sample
	Intervention group (n = 102)		Control group (n = 134)
	Mean	SD	Mean	SD	p Value*
Salivary CAR, nmol/L
Pre	4.70	7.14	2.62	5.50	.058
Post	2.15	8.41	2.26	9.03	.995
Follow-up	2.58	6.58	1.89	6.64	.708
Pre to post	−3.28	10.75	−0.26	12.00	.086
Pre to follow-up	−2.07	9.00	−1.34	7.48	.488
Post to follow-up	−0.02	10.13	−1.21	10.52	.534
Salivary Total cortisol (AUC), nmol/L
Pre	71.65	33.65	65.87	34.81	.100
Post	64.74	23.61	68.11	32.15	.649
Follow-up	64.51	25.68	63.04	26.61	.454
Pre to post	−11.44	37.26	0.36	41.05	.020*
Pre to follow-up	−10.27	40.31	−9.45	30.94	.879
Post to follow-up	−0.49	31.77	−5.28	36.72	.807
Hair cortisol, pg/mg
Pre	5.83	6.14	4.43	3.22	.121
Follow-up	6.87	7.30	5.38	5.65	.355
Pre to follow-up	−0.69	6.60	−0.90	5.09	.672

*Statistical comparisons were performed with Mann–Whitney-U-test.

A p value < .05 was marked with*.

SD: standard deviation; DASS: depression anxiety stress scale; CAR: cortisol awakening response.

DASS measures are presented in Supplementary Table 1.

Table 3. Linear regression analyses for hair- and salivary cortisol change in the control and intervention group from pre- to post-assessment, from pre-assessment to follow-up, and from post-assessment to follow-up.

	Intervention group vs. control group
	Pre-assessment to post-assessment	Pre-assessment to follow-up	Post-assessment to follow-up
	β-coefficients (95% CI)
Salivary CAR change
Age-adjusted	−2.71 (−6.16; 0.73)	−0.71 (−3.45; 2.03)	0.60 (−2.77; 3.98)
Multivariable-adjusted model 1	−2.92 (−6.43; 0.57)	−0.85 (−3.92; 2.20)	0.55 (−2.95; 4.06)
Multivariable-adjusted model 2	−0.64 (−3.42; 2.14)	0.65 (−1.48; 2.78)	0.18 (−2.04; 1.42)
Salivary total cortisol (AUC) change
Age-adjusted	−10.48 (−23.02; 2.05)	−0.29 (−13.59; 12.99)	3.23 (−9.27; 15.74)
Multivariable-adjusted model 1	−13.83 (−26.85; −0.81)*	−0.83 (−15.81; 14.15)	6.57 (−5.52; 18.68)
Multivariable-adjusted model 2	−8.54 (−17.63; 0.54)	2.31 (−6.57; 11.20)	2.53 (−6.60; 11.66)
Hair cortisol change
Age-adjusted	–	0.07 (−1.65; 1.80)	–
Multivariable-adjusted model 1	–	0.53 (−1.66; 2.73)	–
Multivariable-adjusted model 2	–	−0.08 (−2.21; 2.04)	–

Data are β-coefficients and their 95% confidence interval.

A p value < .05 was marked with*. Multivariable-adjusted models 1 were adjusted for age, sex, body mass index, physical activity, educational status, and inhalative corticosteroid medication. Multivariable-adjusted model 2 was additionally adjusted for pre-assessment cortisol indices.

CI: confidence interval; CAR: cortisol awakening response; AUC: area under the curve.

Table 4. Multivariable mediation analyses of total salivary cortisol (pre–post) in the association of DASS change with group affiliation.

	Intervention group vs. control group
	DASS change: pre-assessment to post-assessment	DASS change: pre-assessment to follow-up	DASS change: post-assessment to follow-up
	β-coefficients (95% CI)
Mediation total salivary cortisol (AUC) change
Total effect	−4.35 (−6.51; −2.33)*	1.21 (−0.76; 3.02)	−0.12 (−1.89; 1.52)
Direct effect	−4.24 (−6.45; −2.21)*	1.19 (−0.81; 3.03)	−0.05 (−1.86; 1.59)
Average causal mediation effect (ACME)	−0.10 (−0.54; 0.21)	0.02 (−0.27; 0.31)	−0.06 (−0.39; 0.18)

Data are β-coefficients and their 95% confidence interval with p < 0.05 marked as *. Given that there was no main effect of CAR and hair cortisol when examining Hypothesis 1, CAR and hair cortisol as mediator were not analyzed, and AUC was only considered as a mediator as AUC change from pre to post (not from pre to FU or post to FU). The total effect is the effect of X on Y (without the mediator). The direct effect is the effect of X on Y after considering a mediation (indirect) effect of cortisol. The average causal mediation effect (ACME) is the total effect minus the direct effect. This indirect effect is the mediation effect. Models were adjusted for age, body mass index, physical activity, educational status, baseline DASS, and inhalative corticosteroid medication.

CI: confidence interval; CAR: cortisol awakening response; AUC: area under the curve; DASS: depression anxiety stress scale.