The last quarter-century has witnessed a growing interest into attempts to identify determinants in the aetiologies of mental disorders. Evidence indicates complex aetiologies involving numerous (and interacting) genetic and environmental factors.

Findings from empirical investigations relying on surrogate measures of genetic risk (i.e., family history of mental disorders) and aggregate heritability (i.e., twin pairs) argued for a strong influence of heritable components/genetic vulnerability.

First attempts to obtain evidence from studies making use of molecular genetics sparked excitement in the scientific community. Initially, the field generated a bulk of largely irreproducible results, furthermore occluded by selective reporting of positive findings and lack of replication attempts with adequate power. These early difficulties gave rise to unprecedented collaboration and replicable findings in the area of psychiatric genetics.

Epidemiological research into environmental factors in psychiatry has yielded consistent findings over decades, and identified several (proxy) environmental risk factors associated with mental disorders. These comprise childhood trauma, immigration and minority status, urbanicity, cannabis use, and obstetric and pregnancy complications. Although the effects of these risk factors may be genetically confounded to a degree, evidence from controlled studies suggests that a substantial part is environmental.

Recent evidence from a range of animal studies has indicated that non-genetic inheritance of the influence of traumatic stress may co-determine variability in functional abilities of the brain and in behavioural profiles of offspring.

While this concept has great potential for psychiatry as well as the broader fields of medicine and society, actual studying non-genetic inheritance in humans is very challenging and filled with potential pitfalls.

The presentation will cover the complex aetiologies of mental disorders and provide a critical overview of first human studies on transgenerational inheritance, with a focus on the relation between trauma and health.