The psychiatric genetics literature contains few references to specific environmental factors that cause psychiatric disorders, and while researchers acknowledge a role for these factors, they usually claim that environmental causes are mysterious or unknown. As a leading group of psychiatric genetic researchers recently put it, while claiming that schizophrenia “has a substantial genetic contribution,” the “underlying causes and pathogenesis of the disorder remains unknown.”1 But research suggests otherwise.
As superbly reviewed by psychologist John Read in the 2013 second edition of Models of Madness: Psychological, Social and Biological Approaches to Psychosis, since the turn of the 21st century many studies have linked schizophrenia and other psychotic conditions to childhood adversities such as having experienced bullying, emotional abuse, incest, neglect, parental loss, physical abuse, or sexual abuse—findings that are well known to clinicians who work with people diagnosed with psychotic disorders.2
Read reviewed research linking schizophrenia and other psychotic disorders to social environments such as poverty, racism, migratory stress, and urbanicity. He concluded, “There is ample evidence that inequality, deprivation and discrimination, filtered through their social and personal meanings, are key causal factors in psychosis.” Psychological processes identified by Read and his colleagues, through which childhood adversities may lead to symptoms of psychosis later in life, include attachment, dissociation, dysfunctional cognitive processes, psychodynamic defenses, problematic coping responses, impaired access to social support, behavioral sensitization, and revictimization.3 A biologically oriented commentator might object that even if these factors play a role in causing schizophrenia and psychosis, only people who are genetically predisposed will develop them, and it is therefore important to understand and study hereditary factors. Aside from the fact that the evidence in support of genetics is weak, a clear understanding of the environmental causes of a condition frequently renders potential genetic factors irrelevant.
For example, 33 miners were trapped underground for 69 days in a copper mine near Copiapó, Chile in 2010. Although the miners were finally rescued and were treated as heroes, and in some cases as celebrities, many subsequently developed severe psychological symptoms caused by their ordeal, such as depression, anxiety, nightmares, and avoidant behavior. Because the causes of these symptoms are obvious and recognized, no one to my knowledge has suggested that the miners have genetically based brain disorders or “chemical imbalances.” It is clear that the miners’ experiences caused their symptoms, and the symptoms of most psychiatric conditions can also be seen in this way.
Adverse childhood and adult experiences and environments play a role comparable to the Copiapó mine experience of the 33 trapped Chilean miners. The main difference is that the causes of psychological distress are more obvious, and therefore more recognized, in the Chilean miners’ case. It could also be argued that several Chilean miners were diagnosed with post-traumatic stress disorder (PTSD), a psychiatric diagnosis recognizing that trauma plays a role in causing the symptoms. However, although in the case of PTSD psychiatry chooses to recognize trauma as a causative factor, one could argue that people’s emotional distress and dysfunction, falling into various psychiatric disorder (DSM) categories, are also caused by having experienced trauma and other adverse environmental conditions and events, regardless of any possible role that genetics may play.
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(This posting is adapted from a section of Chapter 8 of The Trouble with Twin Studies: A Reassessment of Twin Research in the Social and Behavioral Sciences)
1. Rees, E., O’Donovan, M. C., & Owen, M. J., (2015), Genetics of Schizophrenia, Current Opinion in Behavioral Sciences, 2, 8-14, p. 8.
2. See the chapters by John Read, in Read, J. & Dillon, J., (Eds.), (2013), Models of Madness: Psychological, Social and Biological Approaches to Psychosis (2nd ed.), London: Routledge.
3. Read, J., Fosse, R., Moscowitz, A., & Perry, B., (2014), The Traumagenic Neurodevelopmental Model of Psychosis Revisited, Neuropsychiatry, 4, 65-79.