Identifying environmental risk and resilience factors determining mental health states in endocrine-sensitive life stages

Throughout lifetime, the interplay between the environment and the genome shapes an individual’s mental health state. At critical phases, susceptibility to mental illness is heightened; these “programming phases” are most prominent during early life and re-occur during challenging phases, such as puberty, pregnancy, and transition into older age. Notably, such programming and challenging phases are partly driven by endocrine stimuli and characterised by hormonal fluctuations, which implicates an important role of the endocrine system in shaping mental health. The EU-funded project RE-MEND addresses the interplay between environmental and genetic factors and the endocrine system at selected lifestages by combining data from population based and clinical studies as well as experimental investigation to identify risk and resilience factors for mental ill-health. The most consistent findings at all investigated life stages so far are clear sex differences in susceptibility to both genetic and environmental risk factors, whereby females are always more susceptible. In early life, maternal stress during pregnancy and prenatal exposure to endocrine disrupting chemicals were identified as environmental risk factors, the latter strengthening the importance of hormonal involvement. On the other hand, maternal nutritional quality during pregnancy was identified as a protective factor. Other environmental risk factors identified so far are pre-pubertal inorganic arsenic exposure for internalising behaviour after puberty in a Bangladeshi population and air pollution for anti-depressant use at older age in a Swedish population. Such insights can ultimately inform targeted prevention strategies to decrease risk factors for mental ill-health.