4. The many sources of disease heterogeneity

COEX 

While phenotype constructs, analytical choices, and sample bias do add to the heterogeneity of a disorder, true variability of the disorder is an important hurdle to overcome to understand its etiology. Efforts to parse the true variability in mental health disorders (such as subtyping) have been stymied by just how wide ranging and complex the sources of heterogeneity in the disorders are. This includes sources of heterogeneity coming from clinical, neurobiological, and genetic domains amongst many others. The relationships between these sources of heterogeneity are not necessarily one-to-one, the presence of many-to-one or possibly many-to-many has been suggested. My work has shown the presence of a many to one relationship between neurobiological and clinical sources of heterogeneity in depression. However, I will discuss beyond just my work for a comprehensive overview of the many sources of heterogeneity in mental health disorders and touch on possible ways for future work to overcome hurdles caused by this heterogeneity.