The phenotypic associations and gene-environment underpinnings of socioeconomic status and diurnal cortisol secretion in adolescence

Low income and schizophrenia risk: a narrative review

Despite decades of research, the precise etiology of schizophrenia is not fully understood. Ample evidence indicates that the disorder derives from a complex interplay of genetic and environmental factors during vulnerable stages of brain maturation. Among the plethora of risk factors investigated, stress, pre- and perinatal insults, and cannabis use have been repeatedly highlighted as crucial environmental risk factors for schizophrenia. Compelling findings from population-based longitudinal studies suggest low income as an additional risk factor for future schizophrenia diagnosis, but underlying mechanisms remain unclear. In this narrative review, we 1) summarize the literature in support of a relationship between low (parental) income and schizophrenia risk, and 2) explore the mediating role of chronic stress, pre- and perinatal factors, and cannabis use as established risk factors for schizophrenia. Our review describes how low income facilitates the occurrence and severity of these established risk factors and thus contributes to schizophrenia liability. The broadest influence of low income was identified for stress, as low income was found to be associated with exposure to a multitude of severe psychological and physiological stressors. This narrative review adds to the growing literature reporting a close relationship between income and mental health.

‘Doctor, I am so stressed out!’ A descriptive study of biological, psychological, and socioemotional markers of stress in individuals who self-identify as being ‘very stressed out’ or ‘zen’

Surveys report that about three-quarters of visits to general practitioners in America are for stress-related complaints. Animal and human studies have consistently demonstrated that exposure to acute and/or chronic stress leads to the activation of the autonomic nervous system (ANS) and/or hypothalamic-pituitary-adrenal (HPA) axis, and to the production of catecholamines and glucocorticoids. Yet, many studies performed in humans do not report significant associations between subjective feelings of stress and increases in these stress biomarkers. Consequently, it is not clear whether the stress-related complaints of individuals are associated with significant increases in these stress biomarkers. In the present study, we measured whether individuals who self-identify as being ‘very stressed out’ or ‘zen’ present differences in psychological (depression and anxiety symptoms), biological (basal and reactive levels of glucocorticoids and alpha-amylase) and socioemotional (emotion regulation, mind wandering, personality, resilience and positive mental health) factors associated with stress. Salivary levels of cortisol and alpha-amylase were obtained in the home environment and in reaction to the Trier Social Stress Test in 123 adults aged between 19 and 55 years. All participants completed questionnaires assessing the psychological and socioemotional factors described above. The results showed that groups significantly differed on almost all psychological and socioemotional factors, although we found no significant group differences on biological markers of stress (cortisol or alpha-amylase). These results suggest that when people complain of being ‘very stressed out’, what they may really be alluding to is an experience of psychological distress that is related to poor emotion regulation capacities. It is thus possible that the construct of stress used by people to discuss their internal state of 'stress' is quite different than the construct of stress measured in animal and human laboratories using biomarkers of 'stress'.

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‘Very stressed out’ individuals present more symptoms of depression and anxiety than ‘zen’ individuals.

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They also present more difficulties in emotion regulation and more mind wandering.

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However, there is no difference between groups on basal alpha-amylase and reactive cortisol and alpha-amylase.

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‘Stress’ in the public may be more related to difficulties in emotion regulation capacities than to dysregulations of stress biomarkers.