Mental health problems are the leading cause of disability among youth, making this a public health issue of major proportions.  By age 16, it is estimated that 36.7% of the population have had at least one disorder. While some treatments are available and effective, more debilitating mental health conditions like schizophrenia, bipolar disorder, and severe depression oftentimes prove much harder, and carry with them a life-long risk of disability. For  interventions to be both effective  and suitable, research is required into the nature, causes, and development of mental illness.

 

We do know mental illnesses tend to run in families, for reasons over and above simply sharing a common household, thus implicating genetic causes. But mental illnesses are also associated with adversity, trauma, and socioeconomic disadvantage, with strong evidence that these conditions precede the illness rather than follow it, indicating the influence of environmental factors.

 

The nature-nurture stalemate is now outmoded for understanding psychiatric illnesses. Experts from biology now suggest that genetic and environmental influences cannot  be viewed separately from one another. Instead, the causes for any affected individual are understood to include both genetic  and  environmental  factors. Specific  cases of such causal mechanisms are  gene-environment interactions (GXEs), where genetic variation and environmental exposure act interdependently, offering complementary, rather than competing, explanations. Neither the genetic variant nor the environmental exposure constitutes a sufficient cause of illness, and it arises only if the two (or more) factors concur. Many definite GXEs have been reported in the literature for psychiatric conditions with multiple causal pathways for the same illness.

 

Examination of GXE for the development of psychiatric conditions also holds the prospect of explaining individual psychiatric variation in both vulnerability and resilience to environmental risks. As such, researchers predict that if we can begin to disentangle the causes, this may help  predict the large variations in response to psychiatric treatment  In sum, GXE modelling of psychiatric illness promises to provide a basis upon which to: i. individualize,  or make  more specific, psychiatric  treatments and health interventions;  and ii. strategize prevention measures and therapeutics that could be more targeted and therefore more efficient and effective from a public health perspective.