A phenotype of resiliency? cross-sectional psychobiological differences between caregivers who are vulnerable vs. resilient to depression, and controls
Introduction: Being a caregiver of chronically ill children is a source of chronic-psychological stress affecting general physical and mental health. However, there is tremendous variance among caregivers: some may develop stress-related depression, whereas others are more “resilient”. The objective of the study was to phenotypically differentiate on psychobiology caregivers who developed depressive symptoms (“vulnerable”) vs. those who did not (“resilient”) from each other and from age-matched controls.
Methods: Forty-five mothers of chronically-ill children and 18 controls have been examined. Caregivers were divided via a median split of Center for Epidemiological Studies Depression Scale scores in “resilient” (RCs) and “vulnerable” (VCs). We assessed cognitive, affective, metabolic, neuroendocrine and oxidative markers at rest and in response to a laboratory social stressor. ANCOVAs and Bonferroni post-hoc tests were used to examine between-group differences.
Results: Although RCs compared to VCs had similar levels of objective parenting-related burden (P = 0.51), they had lower subjective distress (P < 0.01) and higher levels of positive affect (P = 0.04). Although RCs compared to controls had higher levels of objective parenting-related burden (P = 0.04), they had greater cortisol suppression post-dexamethasone (P = 0.05), lower F2-isoprostanes/vitamin E ratio (P < 0.01) and lower fasting insulin levels (P = 0.06).
Discussion: Our results suggest that caregivers with higher resiliency demonstrate more salutary stress-related functioning in comparison with less resilient caregivers and, more surprisingly, non-caregiver controls. These findings might be interpreted in the spirit of Nietzsche's quote “What does not kill me, makes me stronger” and of the idea that successfully overcoming adversity may be more psychobiologically beneficial than not having been exposed to any adversity
