A systematic review of the neuroanatomy of dissociative identity disorder

Dissociative Identity Disorder (DID) is a complex and controversial diagnosis that has undergone multiple revisions in the Diagnostic and Statistical Manual of Mental Disorders (DSM) since its recognition in the 1950s (North, 2015). There is not a clear understanding of DID etiopathology, there is no standardized method of diagnosis, and as such, the disorder has been plagued by a history of fabrication case studies (North, 2015). For these reasons, the disorder is opposed by many psychiatrists. To address this controversy, researchers have begun to examine the neurological basis of DID in an effort to provide stronger physical evidence for the disorder. While this line of inquiry is in its infancy, the purpose of the present systematic review is to examine the existing research on the neuroanatomical brain changes associated with DID in an effort to validate the disorder and provide a foundation for the future development of more accurate and reliable diagnostic techniques. When compared to the brains of normal controls, DID patients show smaller cortical and subcortical volumes in the hippocampus, amygdala, parietal structures involved in perception and personal awareness, and frontal structures involved in movement execution and fear learning. DID patients also show larger white matter tracts that are responsible for information communication between somatosensory association areas, basal ganglia, and the precuneus. These neuroanatomical changes appear to be associated with common DID symptoms such as host dissociation, neurotic defense mechanisms, and overall brain activation/circuitry recruitment. This is the first study to systematically review existing MRI data on DID patients and link it to common behavioral symptoms seen with the disorder. The neuroanatomical evidence for the existence of DID as a genuine disorder is growing and the structural differences seen in DID patients’ brains, as reviewed in this report, contribute to that growth.