Daily Stress and Cortisol Patterns In Parents of Individuals with a Serious Mental Illness

Background and Purpose: Little research has focused on the physiological impact of parenting an adult child with a severe mental illness (SMI) such as schizophrenia, bipolar disorder or major depression. Cortisol is a biomarker of hypothalamus-pituitary-adrenal (HPA) axis activation that plays an important role in mediating the effects of life stressors on physical health. Chronic stress exposure can lead to persistently low levels of circulating cortisol, a pattern of hypoactivity that is symptomatic of wear and tear on the HPA axis. In this study, we examine the cortisol awakening response (CAR) and daily decline in cortisol in parents of adults with a SMI, and compare it to the pattern manifested by parents of non-disabled adult children. We expected that parents of individuals with an SMI would exhibit a flatter CAR and flatter daily decline in cortisol on days following more severe stress.

Methods: Participants completed the National Study of Daily Experience (NSDE) protocol, one of the projects that comprise the National Survey of Midlife in the United States (MIDUS). The NSDE protocol involves 8 days of evening telephone interviews and 4 days of saliva collection. A total of 61 parents who participated in the NSDE self-identified as having an adult child with a SMI. A comparison sample (N = 321) of parents with at least one living child, but no child with a disability was also drawn from the MIDUS/NSDE.

The number and severity of daily stressors were assessed during the phone interviews with the Daily Inventory of Stressful Events. Cortisol concentrations were quantified with a commercially available luminescence immunoassay. The cortisol awakening response (CAR) was calculated by subtracting wake values from the 30 minutes after waking values. Daily decline was calculated by subtracting the bed time values from the 30 minutes after waking values.

Results: Parents of individuals with a SMI experienced more stressful events and had higher average ratings of stress severity than parents in the comparison group. On average, cortisol declined less during the day for parents in the SMI group relative to the comparison group.

Multilevel modeling was used to determine whether associations between subjective experiences of stress and next-day cortisol expression differed for the two groups. Between-persons effects of parent gender, parent age, and allergy, steroid, hormonal, and anxiety/depression medication were controlled. For both daily rhythm parameters, the between-persons by within-person interaction of previous-day subjective stress severity and parent group was significant. Compared to parents of adult children without a disability, parents of individuals with a SMI had less pronounced CAR and less pronounced daily decline on days that followed high stress days.

Conclusions and Implications: These results add to a growing body of evidence that the long-term effect of parenting an adult with a disability has a biological impact on aging parents. The findings support the need for social work interventions across adulthood and into old age for parents of individuals with SMI aimed at reducing stress exposure within and outside the caregiving roll and promoting adaptive coping skills to reduce reactivity to stress.