Expert Commentary. Understanding the mechanisms driving the onset of major psychiatric illnesses such as depression, bipolar disorder and schizophrenia has been far more challenging than expected. Contributing factors include that symptoms associated with each of these disorders overlap during different phases of emerging illness1 and over the course of established illness.2 In addition, while there is evidence supporting specificity of familial segregation,3 at least some genetic risk factors appear to be shared4 and treatment response crosses currently defined diagnostic boundaries.5 

But does it follow, as some propose,6 that psychiatric illnesses are really different manifestations of a common origin—in other words that different psychiatric illnesses derive from pluripotent or shared beginnings and specific outcomes depend on mediating and moderating influences?. To read the full article, log in using your NHS OpenAthens details.