Abstract
Causality of mental disorders is usually complex. Commonly, an interplay of genes and environment is found.
We distinguish gene-environment correlation (rGE), when genetic factors influence whether the subject is exposed to a certain environment, and gene-environment interaction (GxE), where genes determine liability of the subject to environmental factors. This review sums up basic GxE findings in mood disorders, schizophrenia, anxiety disorders, substance addictions and other psychopathological phenomena.
A pioneering work in this field was done by Caspi et al. about ten years ago. Their revelations were related to stressful life events and the serotonin transporter gene inducing depression and suicidal behavior, as well as mono-aminooxidase A gene polymorphism and antisocial behavior of boys who had been abused.
In the discussion section, we mention recent problems in the GxE research in psychiatry, e.g. how to exactly measure the influence of environment or the mental disorder itself, which is sometimes divided into invididual subtypes. Some published critical opinions suggest that so far presented positive findings are mostly "false positive" ones.
That is why we mention several measures how to prevent this in future research. It is necessary to rationalize a sample size using statistical methods, choose genes proper for research based on the findings of genome-wide association studies, asses the influence of environment in a prospective and quantitative way, look for interactions among many genes and many environmental factors simultaneously, meta-analyze published results, and last but not least, unify methods of GxE research in psychiatry.
Looking for gene-environment interactions in psychiatry may lead to causal treatment of mental disorders, their prevention, and destigmatization in the future.