Alien hands and fake feces: Scientists create bizarre new OCD treatment

Researchers attempt to unlock the “prison of the mind” using a strange science experiment.

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Obsessive compulsive disorder wreaks havoc on the lives of approximately two to three percent of the world’s population. But despite its prevalence, one of the most-common treatments for the condition can also be extremely distressing, and even lead people to avoid or drop out of treatment before they see any benefit.

To try get more people with OCD access to therapies that work, researchers have developed a bizarre — but potentially cheap and effective — therapy involving a rubber hand, fake feces, and a piece of cardboard. It’s called “multisensory stimulation therapy,” and could transform the current approach to treating OCD.

The therapy is based on a fascinating mind trick, known as the “rubber hand illusion.” Standard OCD treatments include exposure and response prevention therapy — a kind of cognitive behavioral therapy that involves confronting your fears the hard way. But the problem with this and other treatments is that the treatment itself can cause debilitating fear. Using the illusion, on the other hand, may sidestep the need for them entirely.

The therapy is detailed in a paper published this week in the journal Frontiers of Human Neurosciences.

Unlocking the “prison of the mind”

OCD can be horrible to live with, Baland Jalal, study co-author and neuroscientist at the University of Cambridge, tells Inverse.

“It’s a prison of the mind; it’s extremely cruel,” Jalal says. “Doctors who treat patients and researchers like myself— we know how burdensome can be.”

"We aren’t trying to make a mockery of this; we are trying to be really creative and come up with new out-of-the-box solutions.

In their new study, Jalal and his team used the “rubber hand illusion” (RHI), an unconventional experiment which tricks the brain into thinking a fake hand is part of one’s body.

In the illusion, participants sit with both hands resting on either sides of a partition. The participants’ right hand is obscured from vision, while a rubber hand is visible where their right hand should be. Researchers then use paint brushes to stroke both the “alien” hand and real hand. After a few minutes, participants report feeling brush strokes on the fake hand as if it were their real hand.

The illusion has previously been used with patients dealing with other psychiatric conditions like body dysmorphia and schizophrenia, but never OCD. Until now.

If further trials confirm the results, the treatment could change the lives of people with OCD — many of whom can’t access or afford more expensive or immersive treatments, like exposure and response prevention, or virtual reality.

The exposure effect

The 29 study participants, all patients diagnosed with OCD, were split into two groups: 16 patients had both the rubber and real hand stroked at the same time or “in sync” while 13 participants had the two hands stroked at different times.

Five minutes into the experiment, the participants were asked to rate how much the “alien” hand felt like their own. Both the in-sync and out-of-sync groups felt sensations from the fake hand as if it were their own.

Then, in an icky turn of events, the experimenter used a tissue to smear fake feces on the rubber hand, while simultaneously dabbing a damp paper towel on the participant’s real right hand. This fake poop step is designed to create the sensation of having a contaminant smeared on one’s real hand.

There’s a reason why the researchers picked fake feces: Obsessive compulsive disorder can make aspects of daily life extremely anxiety-inducing. One in four people with the disorder are believed to have a severe fear of contamination — from germs, dirt, feces, or other contaminants. This can keep people with OCD from touching common objects like toilet seats or subway poles, and hinder their ability to keep a job or be in public spaces.

OCD can make seemingly simple tasks, like turning a doorknob, a terrifying challenge.

Suriyo Hmun Kaew / EyeEm/ Getty Images

The most common treatment for the phobia — exposure and response prevention — challenges patients to touch contaminated surfaces and resist washing their hands. The process can be overwhelming and provoke high levels of anxiety, leading almost 25 percent of people with OCD to avoid or drop out of the treatment before receiving the benefits.

Faking it — and making it

This is where the fake hand comes in handy. After their false exposure, study participants were then asked to rate their disgust and anxiety levels, as well as how much they wished to wash their hands. The experimenter also recorded the participant’s facial expression of disgust. Then, the experimenter removed the damp paper towel and left the fake feces on the “alien” hand. They kept stroking both hands with the paint brushes for another five minutes.

The longer the experiment progressed, the more disgusted participants were. After ten minutes, 65 percent of the in-sync participants showed disgust on their face, while 35 percent of the out-of-sync participants showed facial expressions of disgust.

Set up of multisensory stimulation therapy. 

Craig Brierley (Cambridge University)

After all that, the experimenter stopped stroking participants’ hands and smeared the fake poop on their real hand. Once again, the experimenter gathered data on anxiety levels, disgust levels, and desire for hand-washing. Participants whose hands were previously stroked at the same rate — the in-sync group — had 23 percent higher levels of anxiety, disgust, and desire for hand-washing than those whose hands had not been stroked at the same rate.

Stroking the real and fake hands appears to fool participants into thinking the fake, poop-smeared hand is their own, Jalal says. Although he and his team didn’t look at when or how the feelings of disgust eventually went away, the results suggest that the illusion could elicit similar results to traditional exposure therapy — but a fake hand would be exposed to the contaminant they are scared of, rather than their own body.

Repeatedly undergoing the process with the guidance of a health professional may help them ultimately overcome their contamination-related fears, Jalal says.

“If you can provide an indirect treatment that is reasonably realistic, where you contaminate a rubber hand instead of a real hand, this might provide a bridge that will allow more people to tolerate exposure therapy or even to replace exposure therapy altogether,” he says.

Surprisingly, study participants didn’t just experience disgust and anxiety — they also reported astonishment, and some even started giggling. Channelling these emotions could also help people overcome their OCD-related phobias.

More randomized-control trials are needed to test whether the treatment is as effective as standard treatments for OCD. If researchers can confirm that, the new, if odd, approach has clear advantages, Jalal says.

“Whereas traditional exposure therapy can be stressful, the rubber hand illusion often makes people laugh at first, helping put them at ease,” he says. “It is also straightforward and cheap compared to virtual reality, and so can easily reach patients in distress no matter where they are, such as poorly resourced and emergency settings.”

Obsessive-compulsive disorder (OCD) is a deeply enigmatic psychiatric condition associated with immense suffering worldwide. Efficacious therapies for OCD, like exposure and response prevention (ERP), are sometimes poorly tolerated by patients. As many as 25% of patients refuse to initiate ERP mainly because they are too anxious to follow exposure procedures. Accordingly, we proposed a simple and tolerable (immersive yet indirect) low-cost technique for treating OCD that we call “multisensory stimulation therapy.” This method involves contaminating a rubber hand during the so-called “rubber hand illusion” (RHI) in which tactile sensations may be perceived as arising from a fake hand. Notably, Jalal et al. (2015) showed that such fake hand contamination during the RHI provokes powerful disgust reactions in healthy volunteers. In the current study, we explored the therapeutic potential of this novel approach. OCD patients (n = 29) watched as their hidden real hand was being stroked together with a visible fake hand; either synchronously (inducing the RHI; i.e., the experimental condition; n = 16) or asynchronously (i.e., the control condition; n = 13). After 5 min of tactile stimulation, the rubber hand was contaminated with fake feces, simulating conventional exposure therapy. Intriguingly, results suggested sensory assimilation of contamination sensations into the body image via the RHI: patients undergoing synchronous stimulation did not report greater contamination sensations when the fake hand was initially contaminated relative to asynchronous stroking. But contrary to expectations, they did so after the rubber hand had been contaminated for 5 min, as assessed via disgust facial expressions (a secondary outcome) and in vivo exposure (upon discontinuing the illusion). Further, to our surprise, synchronous and asynchronous stroking induced an equally vivid and fast-emerging illusion, which helps explain why both conditions initially (5 min after initiating tactile stimulation) provoked contamination reactions of equal magnitude. This study is the first to suggest heightened malleability of body image in OCD. Importantly, it may pave the way for a tolerable technique for the treatment of OCD—highly suitable for poorly resourced and emergency settings, including low-income and developing countries with minimal access to high-tech solutions like virtual reality.
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