It has been very limited with the research into depersonalization disorder since the depersonalization research unit stopped in 2015. But, there has been a lot of research in PTSD and the dissociative subtype that features of depersonalization and derealization. Among people with PTSD it is estimated that 15% of the have the dissociative subtype. There are some significant overlapping between the dissociative subtype of PTSD and depersonalization disorder. They both share symptoms of emotional numbing, detachment, derealisation. So, it is assumed that the emotional regulation done by the brain is likely the same. So, findings in the dissociative subtype of PTSD can also be used in depersonalization. The leading researcher into the dissociative subtype of PTSD is the Canadian prof in psychiatry, Ruth Lanitus. Here is lecture with her from 2019 based in recent brain scans in PTSD and its dissociative subtype. The recording in not so good as it is recorded from distance but it can be seen. Her point is the dissociation comes from overregulation of emotion done by the ventromedial prefrontal cortex- emotions are suppressed. An area deep in the midbrain called the “periaqueductal gray”/PAG is in the ventral part active in the dissociative state, - all the time. It is a old structure in the brain we share with reptiles. A structure millions of years old.
In normal PTSD the periaqueductal gray is active in the dorsal part, -all the time. They are in a constant state of alert/fight and flight mode. Their emotions are under regulated as the ventromedial prefrontal cortex is underactive- opposite to the dissociative subtype. They can have emotional outburst, have range due to this under regulation. Their constant state of alert does they have difficulty to find rest and be relaxed.
The dissociative state is a immobilization response that the brain have chosen because a fight and flight response could not be taken. Danger was perceived as being to close. Symptoms like out of body, derealisation is likely connected to the activation of the periaqueductal gray. Emotional numbing is likely result of the overactivity/emotional regulation done by the ventromedial prefrontal cortex.
So, she have recent data from brain scan that shows the involvement of the periaqueductal gray. This is not found in other studies in depersonalization. They likely could scan that area until recently. She points towards ventromedial prefrontal cortex as central in this regulation. The ventromedial prefrontal cortex -both left and right have also been found overactive in studies in depersonalization. It is a location very difficult to manipulate with until recently, as it is to deep to stimulate with rTMS. There have been development of new coils that can likely affect it. But, it is not used by rTMS providers yet.
her lecture is here.