Circulating levels of oxytocin may be elevated in complicated grief: a pilot study

Figures & data

Table 1. Sociodemographic and clinical characteristics of n = 47 adults with complicated grief and age- and sex-matched bereaved controls (n = 46), and adults with major depressive disorder (n = 46).

	Bereaved Controls	MDD	CG
	(n = 46)	(n = 46)	(n = 47)	Statistic^a	p-value
Female Sex, % (n)	69.6% (32)	69.57% (32)	70.21% (33)	0.0	>0.99
Age, Years, Mean (SD)	48.65 (12.7)	49.33 (13.27)	49.49 (12.87)	0.05	0.95
Race, White, % (n)	80.4% (37)	82.6% (38)	92.7% (38)	2.9	0.24
Ethnicity, Hispanic, % (n)	2.2% (1)	4.6% (2)	0% (0)	2.0	0.38
Highest Education, % (n)				1.5	0.83
Graduate School	34.8% (16)	26.8% (11)	23.9% (11)
College Graduate	34.8% (16)	41.3% (19)	41.5% (17)
High School or Lower	30.4% (14)	34.8% (16)	31.7% (13)
Marital Status, Married/Partnership, % (n)	39.1% (18)	15.2% (7)	29.3% (12)	6.6	0.04
Premenopausal status	30.4% (14)	25.5% (12)	30.4% (14)	0.36	0.83
Relationship to the Deceased, % (n)				13.3	0.01
Parent	42.9% (15)	40% (10)	25.6% (10)
Spouse	8.6% (3)	12% (3)	41.0% (16)
Other	48.6% (17)	48% (12)	33.3% (13)
Blood collection, AM, % (n)	26.1% (12)	12.2% (5) [n = 41]	14.0% (6) [n = 43]	3.5	0.21
Time of blood collection, Mean (SD)	1333 (205)	1434 (217) [n = 41]	1340 (196) [n = 43]	3.2	0.04
Current PTSD, % (n)	0% (0)	20% (9) [n = 45]	72.5% (29) [n = 40]	57.3	<0.01
ICG score, Mean (SD)	6.0 (7.4)	18.47 (15.62)	40.58 (9.84)	112.2	<0.01

^aChi-square for categorical variables, and analyses of variance (F-value) for continuous variables.

PTSD: Posttraumatic Stress Disorder

Figure 1. Plasma circulating oxytocin levels (pg/mL) in bereaved people with a primary diagnosis of complicated grief (CG; n = 47), a primary diagnosis of major depressive disorder (MDD, n = 46), and without psychiatric disorder (bereaved controls; n = 46). Note that the p-values of the pairwise comparisons shown were not adjusted for age, sex, comorbid diagnosis, or menopausal status, as reported elsewhere in the paper.

Table 2. Follow-up regression models predicting plasma (circulating) oxytocin levels with probable complicated grief (CG) and current major depressive disorder (MDD) diagnoses, sex, and their interactions, adjusting for age and premenopausal status.

Predictors	b	SE	t-value	df	p-value
Full model (R^2 = 0.15, adj. R^2 = 0.10, F(8,125) = 2.82, p = 0.007)
Intercept	1416.2	181.5	7.80	1	<0.001
Probable CG (ICG score ≥ 30)	282.9	94.7	2.99	1	0.003
Current MDD	−72.4	94.4	−0.77	1	0.445
Sex (female vs. male)	−58.5	108.4	−0.54	1	0.590
Probable CG × Current MDD	−271.2	179.0	−1.51	1	0.132
Probable CG × Sex	73.7	185.5	0.40	1	0.692
Current MDD × Sex	−386.8	185.2	−2.09	1	0.039
Age	2.7	4.1	0.67	1	0.503
Premenopausal status	338.9	128.4	2.64	1	0.009
Reduced model (R^2 = 0.15, adj. R^2 = 0.10, F(7, 126) = 3.23, p = 0.004)
Intercept	1416.1	180.9	7.83	1	<0.001
Probable CG (ICG score ≥ 30)	294.9	89.4	3.30	1	0.001
Current MDD	−75.7	93.7	−0.81	1	0.421
Sex (female vs. male)	−61.9	107.7	−0.57	1	0.566
Probable CG × Current MDD	−265.3	177.8	−1.49	1	0.138
Current MDD × Sex	−365.1	176.4	−2.07	1	0.041
Age	−2.7	4.0	0.66	1	0.508
Premenopausal Status	335.2	127.7	2.63	1	0.010

Note: Parameters in this table are based on effects coding differences, where the intercept represents the unadjusted estimated population mean (i.e. overall mean, not weighted by unequal group sizes). All simple categorical predictors can be interpreted as group differences or main effects (e.g. the Probable CG effect in the reduced model shows that participants with probable CG had circulating plasma levels 294.9 ± 89.4 pg/mL higher than those without probable CG), while interaction terms test whether the constituent main effects are additive or not.