Loneliness Mediates the Relationship Between Early Life Stress and Perceived Stress but not Hypothalamic-Pituitary-Adrenal Axis Functioning

Many authors have proposed that early life stress (ELS) provokes a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and contributes negatively to the management of stress in adulthood. However, these associations have not always been observed, making it necessary to include new factors that could explain the different results found. In this regard, people with ELS experiences report less social support during adulthood, suggesting that loneliness could be a mediating factor. Thus, our aims were to investigate whether ELS was related to both perceived stress and diurnal HPA axis activity, and whether loneliness mediates these relationships, in a community sample (N=187, 18-55years old). Fourteen cortisol samples were collected on two non-consecutive days to obtain the overall diurnal cortisol, diurnal cortisol slope, and bedtime levels. Additionally, ELS was assessed with the Risky Families Questionnaire (RFQ) and the Recalled Childhood and Adolescence Perceived Stress (ReCAPS) measure. Results revealed that ELS was associated with perceived stress, but not HPA axis functioning, and loneliness mediated the relationship between ELS and perceived stress, but not between ELS and HPA axis functioning. Similar results were found for both ELS questionnaires, suggesting that the ReCAPS is an adequate tool. These results highlight the importance of loneliness in understanding the long-term effects of ELS, and they indicate different effects of ELS on subjective and physiological stress indicators

A low cortisol response to acute stress is related to worse basal memory performance in older people

Age-related memory decline has been associated with a faulty regulation of the hypothalamus-pituitary-adrenal axis (HPA-axis). The aim of this study was to investigate whether the magnitude of the stress-induced cortisol increase is related to memory performance when memory is measured in non-stressful conditions. To do so, declarative and working memory performance were measured in 31 men and 35 women between 55 and 77 years of age. On a different day, the magnitude of their cortisol response to acute psychosocial stress was measured. The relationship between the cortisol response and memory performance was U shaped: a low cortisol response to stress was related to poorer declarative and working memory performance, whereas those who did not increase their cortisol levels and those who had the largest cortisol increase had better declarative and working memory capabilities. Sex did not moderate these relationships. These results suggest that a low cortisol response to stress could reflect a defective HPA-axis response to stressors that is accompanied by poorer memory performance. Conversely, a high cortisol response seems to reflect a correct functioning of the HPA-axis and may protect against memory deficits in the later stages of human life