Borderline, disconnected: dissociation in BPD

The feeling that we are located within our physical body, for most of us, is a fundamental fact of existence. For most people, our brains continually generate this perception using signals from different senses, as well as expectations about what those signals should mean. This perception, however, is vulnerable to interference — and if that happens, the result can be feelings of dissociation from the body, or even a full-blown 'out of body experience' (OBE).  

For some, including those diagnosed with borderline personality disorder (BPD), feelings of bodily dissociation are not rare events. In fact, about 80% of people with BPD report dissociative symptoms — though the reason for this has been unclear. A new study in Personality Disorders: Theory, Research and Treatment, however, suggests that unusual sensory processing may play a key role.

Annette Löffler at Heidelberg University, Germany, and her colleagues studied 22 people with BPD, as well as 16 people who'd had a BPD diagnosis in the past but who were symptom-free, and 20 healthy controls. All underwent a procedure designed to induce an OBE.

This procedure required the participants to sit on a chair positioned between two walls, and to wear a headset that displayed the feed of a camera that was mounted behind them, facing their back and head. The experimental set-up also featured two mechanical paintbrushes. One was positioned so that it could brush the top of the participant's sternum, at the base of their neck. The other paintbrush was mounted in front of the camera. The brushes could be programmed to either move simultaneously, with both making the same brushstroke at the same time, or to move out of sync.

During this procedure, the participants reported on any feelings of dissociation and completed a questionnaire designed to measure OBEs. They also indicated whether they felt that their self was in the same location as their body, or outside it. To do this, they used a paper plan, drawn to scale, to indicate the relative locations of their self and their body.

Earlier work using a similar experimental set-up has shown that, for some people, when the brushing movements are in sync, they come to feel that their self is located outside their normal physical borders, in the location of the camera, where their eyes are telling them the touch is happening.

In this study, the researchers found that whether the brushing was in sync or not, the people with BPD reported a more extreme physical detachment from their body, compared with the other participants. When the brushing was in sync, they also reported having more intense OBEs and they scored higher on the measure of clinical symptoms of dissociation.

This research can't reveal the reasons for these results. However, the team suspects that the brains of people with BPD may have come to trust sensory data caused by external stimuli more than internal, 'interoceptive' data, and this could help to explain their findings.

Interoception covers a number of senses, including heartbeat sensing and also proprioception, which, mostly thanks to sensory signals from your muscles, tells your brain where your body parts are located in space.

People with BPD often report having suffered traumatic childhoods, the team notes, and other research has linked early trauma and abuse with deficits in interoception. If a person's brain starts to rely less on interoceptive signals, and more on data from 'external' senses, this could make them more vulnerable to body-related illusions, such as the 'out of body' illusion that the researchers in this study set out to induce.

Interestingly, the results of people who'd had a BPD diagnosis in the past, but who were currently symptom-free, were similar to those of the healthy participants. It may be the case that such people who no longer meet the criteria for a BPD diagnosis have developed a more typical level of reliance on interoception — further research, however, will be needed to explore this fully.

Read the paper in full:
Löffler, A., Kleinböhl, D., Gescher, D. M., Panizza, A., & Bekrater-Bodmann, R. (2024). Exteroception and the perceived (dis)connection of the body and the self: Implications for the understanding of dissociative self-experiences in borderline personality disorder. Personality Disorders: Theory, Research, and Treatment. Advance online publication. https://doi.org/10.1037/per0000670

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