The specific objectives of the LIFECOURSE study are as follows:
Objective 1: To examine the links between high levels of early life stress and increased physiological stress (labelled “allostatic load” in the physiology literature), emotional reactions and harmful behaviour in adolescence. Our cumulative assessment of early life stress includes measures of both psychosocial and physical stressors from pre-birth and onwards, including family conflict, mother´s (during pregnancy) and child´s physical and emotional status, measures such as ICD-10 for mother and child at time of birth, maternal health and illness during pregnancy, maternal risk behaviour, Apgar score at birth, motor skills, height and weight from birth onwards, and measures of aggression, sensitivity and anxiety in toddlerhood. Adolescent physiological stress is measured as altered basal cortisol levels and rhythms across the day and alpha-amylase. Emotional reactions include self-reported indicators of depressed mood, anger and anxiety in adolescence as well as registry data from school nurses. Harmful behaviour includes self-reported and registry indicators of substance use, self-harm, suicidal and delinquent behaviour in adolescence.
Objective 2: To study the effects of stress in childhood both on individual level as well as on local community/neighbourhood level. Our assessment of early life neighbourhood level stress includes for example measures of area-based clustering of relative deprivation, disrupted families, low income and/or high unemployment neighbourhoods, and areas with high concentration of youth delinquency and substance use that can be assessed independently of individual variation of such measures.
Objective 3: To test whether high support in early adolescence may modify/buffer the effects of early life stress on physiological stress, emotional reactions, and harmful behaviour later in adolescence. This analysis will relate patterns of basal cortisol (i.e., healthy pattern revealed as moderate cortisol awakening response and strong decline in cortisol levels across the day), as well as measures of self-reported emotions and harmful behaviour in late adolescence, to indicators of early adolescent support (e.g., parental emotional support, time spent with parents, organized youth work, and local community/neighbourhood social capital) despite high early life stress, whilst controlling for demographic conditions.