Obsessive compulsive disorder (OCD) could be treat with rubber hand illusion


Obsessive compulsive disorder (OCD) affects as many as one in 50 people worldwide. One of the most common types of the condition, affecting almost a half of OCD patients, is characterised by severe contamination fears – even from touching something as commonplace as a door knob – leading to excessive washing behaviour.

The condition can have a serious impact on people’s lives, their mental health, their relationships and their ability to hold down jobs.

OCD is treated using a combination of medication such as Prozac and a form of cognitive behavioural therapy (‘talking therapy’) termed ‘exposure and response prevention’.

This exposure therapy often involves instructing OCD patients to touch contaminated surfaces, such as a toilet, but to refrain from then washing their hands; however, this experience can be so stressful that many patients cannot take part.

OCD can be an extremely debilitating condition for many people, but the treatments are not always straightforward,” explained Baland Jalal, a neuroscientist based in the Department of Psychiatry at the University of Cambridge.

“In fact, exposure therapy can be very stressful and so is not always effective or even feasible for many patients.”

To overcome this challenge, a team of researchers from the UK and USA tested whether, rather than asking patients to contaminate their own hands, it might be possible to help them overcome their fears by contaminating a fake hand instead – a procedure they call ‘multisensory stimulation therapy’.

The technique builds on a famous trick known as the ‘rubber hand illusion’. In this illusion, an individual places both hands in front of them on a table, either side of a partition such that they cannot see their right hand.

Instead, to the left of the partition they see a fake right hand.

The illusionist – in this case, the experimenter – strokes both the fake hand and hidden right hand using a paintbrush.

After several minutes of stroking the individual often reports ‘feeling’ touch arising from the fake hand as though it was their own.

In the majority of cases, the rubber hand illusion only works if both hands are stroked in synchrony; if they are stroked asynchronously, the illusion is diminished or disappears entirely.

However, in a number of psychiatric conditions such as schizophrenia and body dysmorphic disorder, the illusion appears to work in both cases, suggesting that the body image held in the minds of these patients is more malleable than in healthy individuals.

In a previous study, carried out by Jalal and neuroscientist VS Ramachandran using healthy volunteers, once the illusion had begun to work, the researchers contaminated the dummy hand with fake faeces. The participants reported disgust sensations as if it were their own hand that had been contaminated.

In a new study published today in Frontiers in Human Neuroscience, Jalal and Ramachandran teamed up with researchers at Harvard University – Richard J McNally, Director of Clinical Training in Department Psychology and Jason A Elias and Sriramya Potluri in the Department Psychiatry.

The team recruited 29 OCD patients from the McLean Hospital Obsessive Compulsive Disorder Institute, an intensive residential treatment programme affiliated with Harvard Medical School. Sixteen of these patients had their hidden and dummy hands stroked at the same time, while the remaining 13 patients (the control group) had their hands stroked out of synch.

After 5 minutes of stroking, the participant was asked to rate how much the rubber hand felt like their own. The experimenter then used a tissue to smear the fake faeces on the rubber hand while simultaneously dabbing a damp paper towel on the participant’s real right hand (to create the sensation of having the contaminant smeared on their real hand).

The participant was then asked to rate their disgust, anxiety and handwashing urge levels, and the experimenter rated the participant’s facial expression of disgust.

The researchers found that patients in both the experimental and control groups felt an equally strong rubber hand illusion. In other words, even when their real and fake hands were being stroked asynchronously, they had still begun to sense the fake hand as their own. Unsurprisingly, therefore, patients in both groups initially reported similar levels of contamination.

The experimenter then removed the clean paper towel and the tissue that had been used to contaminate the rubber hand, leaving fake faeces on the rubber hand. The experimenter continued to stroke the rubber hand and the participant’s real hand for an additional 5 minutes, after which the participant again provided contamination ratings and the experimenter rated their facial expression.

Now, the patients in the experimental condition were more disgusted: 65% of participants in the experimental condition had a disgust facial expression compared to 35% in the control. This supports previous studies that show that the rubber hand illusion becomes stronger the longer the hand is stroked.

Next, the experimenter stopped the stroking and placed the fake faeces on the patient’s real, right hand and asked the participant once again to provide contamination ratings.

Now the differences were much more pronounced in the experimental condition. While those in the control group had average disgust, anxiety and washing urge levels at nearly 7, the experimental group had levels of nearly 9 – that is, an overall 23% difference in contamination ratings.

“Over time, stroking the real and fake hands in synchrony appears to create a stronger and stronger and stronger illusion to the extent that it eventually felt very much like their own hand,” said Jalal.

“This meant that after ten minutes, the reaction to contamination was more extreme. Although this was the point our experiment ended, research has shown that continued exposure leads to a decline in contamination feelings – which is the basis of traditional exposure therapy.”

This shows the rubber hand illusion

To overcome this challenge, a team of researchers from the UK and USA tested whether, rather than asking patients to contaminate their own hands, it might be possible to help them overcome their fears by contaminating a fake hand instead – a procedure they call ‘multisensory stimulation therapy’. Image is credited to University of Cambridge.

Jalal says it can be safely assumed that the fake hand contamination procedure would lead to similar fall in levels of disgust and contamination ratings, possibly after 30 minutes.

Jalal says the rubber hand illusion may offer a way of treating OCD patients without the high stress levels that exposure therapy can cause. “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.”

Jalal has previously worked on other indirect treatments for treating patients with OCD, including a smartphone app. He says that unlike other indirect treatments, this new approach creates a compelling illusion that a part of the patient’s body is being exposed to contamination and so could be even more immersive.

It also has additional benefits: “Whereas traditional exposure therapy can be stressful, the rubber hand illusion often makes people laugh at first, helping put them at ease. 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.”

Jalal says the next step is to do randomised clinical trials and compare this technique to existing treatments. Ramachandran agrees, adding: “These results are compelling but not conclusive. We need larger samples and to iron out some methodological wrinkles.”

Other applications of multisensory stimulation therapy might include therapy for people afraid of needles. Exposure therapy would mean repeated needle injections into a real arm and could result in punctured veins. Using a fake hand could provide a clever and convenient alternative.

Obsessive-compulsive disorder (OCD) causes serious difficulties in the everyday lives of people suffering from it; especially in its acute form, it may significantly hinder individuals’ psychosocial functioning [1].

The importance of this issue in the indi- vidual, family and social dimensions is backed by statistical data, according to which ca. 2–3% of the population suffer from OCD [2, as cited in: 3]. Almost all people with

OCD experience difficulties in relations (92% have problems with starting a relation because of low self-esteem; 73% experience problems in their families and 62% in friendships, which are related to the risk of parting), with nearly half of them having problems in the professional area (58% have trouble with continuing education, 47% experience difficulty with keeping a job, and 40% are unable to work); 13% attempt suicide as a result of suffering from obsessions [4, as cited in: 1].

Over 90% of people with OCD meet the criteria related to other psychological disorders [2, 5, as cited in: 3], including depression, bipolar disorder, eating disorders, anxiety disorders, personal- ity disorders, and schizophrenia [1, 3], thus complicating the diagnostic process and treatment.

Another difficulty is caused by a delay in the start of the treatment because of the ‛embarrassing’ nature of OCD (not to mention a lack of insight into the illness); on average, it takes 10 years from the first symptoms to appear before help is sought and around 17 years until appropriate treatment is undergone [4, as cited in: 1].

Ongoing discussions on the nature of the obsessions – whether they are a symp- tom, a consequence, or the cause of anxiety disorders – have resulted in changes in the American classification of mental disorders DSM–5 [3, 6]. OCD, traditionally classified as an anxiety disorder, has been included in a newly created separate group – ‛Obsessive- Compulsive and Related Disorders’ (OCRD) [6] – which includes, apart from OCD, four other disorders: body dysmorphic disorder, trichotillomania (hair-pulling disorder), hoarding disorder, and dermatillomania (excoriation disorder or skin-picking disorder).

This change expresses a different understanding of the psychopathology of OCD, which considers compulsiveness (understood as a tendency to engage in repetitive ac- tions) as the basis of these disorders. As opposed to the previous understanding of OCD, compulsiveness theory assumes that anxiety has no direct functional relation to compulsive symptoms [7, as cited in: 3].

However, compulsiveness is a characteristic feature for many other neuropsychiatric disorders, so it has resulted in an issue of which disorders should be or not be included in the OCRD group. In the case of DSM-5, an arbitrary decision was made as a compromise between those against the changes in the OCD classifica- tion and advocates of creating a broad transdiagnostic category of OCD [8, as cited in: 3] to include the above-mentioned disorders in OCRD but to exclude disorders such as hypochondriasis or olfactory reference syndrome (which, similar to body dysmorphic disorder, involves compulsive behaviors, included in the proposed changes to ICD-11).

With the doubts concerning OCRD put aside, OCD itself is a complex disorder that shows a range of symptoms. This variety is commonly limited by grouping the symp- toms into the following conceptually coherent subtypes:

(1) cleaning (contamination obsessions with cleaning/washing compulsions);

(2) symmetry (symmetry obsessions and repetition, ordering and counting compulsions);

(3) intrusive or taboo thoughts (e.g., sexually or religiously aggressive obsessions and the compulsions related to them – neutralizing behaviors); and

(4) harm (fear of harming oneself or others and checking compulsions).

The subtype involving compulsive hoarding, previously included here, has been made a separate disorder belonging to the OCRD group. Other obsessions and compulsions may include doubts concerning everyday activities (leaving the door

open, leaving the gas on), the need to possess/memorize information (license plates, ads etc.), an obsessive focus on bodily functions (so-called somatic obsessions), and intrusive, non-aggressive fantasies and thoughts or superstitions (‛black cat’, ‛grave- yard’), lucky/unlucky numbers, colors etc. One should note that patients often have symptoms from more than one subtype [6].

The diagnostic criteria for OCD in DSM-5 are relatively simple. The obsessions and/or compulsions must be time consuming (at least an hour per day) or cause sig- nificant suffering or a substantial disruption of one’s functioning in the social, profes- sional or other important areas. Because of the fact that insight into the illness affects its prognosis, such an insight has to be specified for all patients diagnosed with OCD.

The level of insight may be (1) good or satisfactory, (2) poor, or (3) no insight/delu- sional convictions. No insight means that the patient thinks with all certainty that the beliefs related to OCD are entirely true. This usually involves a lack of motivation for treatment and poor prognosis. Apart from an assessment of the level of insight, whether the patient had or has chronic tic disorder should be investigated [6].

The aim of this work is to present the current view on the issue of treatment of obsessive-compulsive and related disorders according to DSM-5, taking into account potential differences in the therapeutic approach that may result from greater heterogene- ity of the included disorders.

We have prepared an overview of various types of OCD/ OCRD treatments by using available digital databases (PubMed, Cochrane, PsycINFO), meta-analyses, review works, randomized clinical trails’ outcomes, and handbooks in English and Polish. We hope that this will be helpful primarily for clinicians and for people helping others who are suffering from obsessions and related disorders on a daily basis.

The diversity of OCD symptoms begs the question of whether it is a disorder with  one or multiple causes. As an attempt to answer this question, a number of models presenting different groups of obsessive-compulsive symptoms, such as biological, cognitive and behavioral models, have been created.

Existing models, however, are far from giving a sufficient explanation of why one person has obsessions related to contracting germs and excessive hygiene, whereas someone else has obsessions and compulsions connected to symmetry and counting, and another person has both classes of symptoms at once [9].

One of the elements included in the biological model of OCD is the reaction to treatment. Knowledge about the differences in reacting to the treatment of OCD/OCRD, apart from its cognitive value, could have great clinical value and help in the choice of the most efficient type of treatment for a given type of disorder or the nature of the symptoms it involves.

As can be seen from an overview of the medical literature, the phenomenology and symptomatology of OCD and OCRD are not entirely coherent. Thus, a tendency to differently approach various disorders within the group can be observed, depending on the presence/intensity of obsessiveness, compulsiveness and impulsivity in the psychopathological picture [4, 10].

Before we proceed to discuss the issues related to the treatment both of the specific subtypes of OCD and the disorders included in OCRD, let us generally present the current standards for treating OCD.

Behavioral therapy is considered the first-choice treatment for OCD. It involves the use of exposure and response prevention (ERP), as well as anti-depressant medi- cation inhibiting serotonin reuptake from the synaptic gap (serotonin reuptake inhibi- tors – SRI).

This group of medications includes selective serotonin reuptake inhibi- tors (SSRIs), such as fluoxetine, sertraline, fluvoxamine, paroxetine, citalopram and escitalopram, as well as clomipramine, which is a non-SSRI. Behavioral therapy is often complemented with additional cognitive techniques, called cognitive behavioral therapy (CBT).

If the above-mentioned methods and medications are insufficient, other treatment methods are added. Below, we will present an algorithm for treating OCD based on the recommendations of the American Psychiatric Association (APA) [11], modified to consider recent studies on the efficacy of OCD treatment [12].

Table 1. Algorithm for treating OCD patients [11, 12]

University of Cambridge
Media Contacts:
Craig Brierley – University of Cambridge

Original Research: Open access
““Fake it till You Make it”! Contaminating Rubber Hands (“Multisensory Stimulation Therapy”) to Treat Obsessive-Compulsive Disorder”. Baland Jalal et al.
Frontiers in Neuroscience doi:10.3389/fnhum.2019.00414.


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