Mental contamination is defined as feeling dirty, contaminated, or polluted in the absence of physical contact with an actual contaminant (Rachman, 2006). The subjective experience of pollution lacks a physical basis (Cougle et al., 2008).

This phenomenon involves sensations of internal dirtiness and urges to wash that arise from experiencing disturbing thoughts, memories, images, or experiences rather than direct contact with something perceived as contaminating (Fairbrother & Rachman, 2004).

Mental contamination provokes cleaning behaviors aimed at removing the feelings of contamination, but these are typically ineffective in reducing the persistent feelings of internal uncleanliness (Rachman, 2006).

It overlaps conceptually with physical contact contamination but is considered a distinct construct centered around internal cognitive-emotional processes rather than external pollutants.

Coughtrey, A. E., Shafran, R., Knibbs, D., & Rachman, S. J. (2012). Mental contamination in obsessive–compulsive disorder. Journal of Obsessive-Compulsive and Related Disorders, 1(4), 244-250. https://doi.org/10.1016/j.jocrd.2012.07.006

Key Points

The study examined mental contamination (feeling dirty without physical contact) in people with OCD symptoms or diagnosis.
46% of participants with OCD symptoms and 44% of those formally diagnosed experienced clinically relevant mental contamination.
Mental contamination was related to but distinct from contact contamination fears.
Mental contamination was associated with OCD symptom severity and thought-action fusion beliefs (that thoughts can influence actions or events)
Mental contamination was related to but separable from general negative affect.
The findings provide preliminary empirical support for mental contamination as a distinct construct relevant to OCD. Further research is needed with larger clinical samples.

Rationale

Past research and clinical observations indicate that feelings of contamination can occur in OCD patients without physical contact with an actual contaminant (mental contamination).

However, there is limited systematic data on this phenomenon. Investigating mental contamination has implications for understanding OCD and optimizing treatment.

The purpose of this two-part study was to examine the presence of mental contamination and its relationships with contact contamination, OCD symptoms, thought-action fusion beliefs, and negative affect in people with obsessive-compulsive problems or OCD diagnosis.

Method

In Study 1, 177 adults who reported they had been diagnosed with OCD by a health professional completed self-report measures of mental contamination (VOCI-MC), OCD symptoms (OCI-R), and thought-action fusion beliefs (TAF).
In Study 2, 54 participants from Study 1 who had received a formal OCD diagnosis using a structured clinical interview completed additional measures of contamination fears, OCD symptoms, thought-action fusion, anxiety, and depression.

The studies examined the rates of clinically relevant mental contamination, the relationship between mental and contact contamination, and associations between mental contamination, psychopathology, and negative affect.

Sample

Study 1 sample comprised 177 adults with obsessive-compulsive problems (130 women; mean age 34 years). Most were recruited through OCD support groups or an OCD referrals database.
Study 2 sample was 54 adults (35 women; mean age 33 years) who had received a formal diagnosis of OCD, recruited from Study 1 participants.

Statistical Analysis

Study 1 used Pearson correlation analyses to examine relationships between mental contamination, OCD symptoms, and thought-action fusion beliefs.
Study 2 used correlation and partial correlation analyses to investigate associations between mental contamination and psychopathology variables while controlling for negative affect. Independent samples t-tests compared negative affect in people with versus without mental contamination.

Results

Mental contamination and its relationship with contact contamination:

46% (Study 1) and 44% (Study 2) of participants scored above the clinical cut-off for mental contamination, indicating clinically relevant mental contamination concerns.
Around 10% experienced mental contamination without contact contamination fears; around 15% had contact contamination without mental contamination. Over a third had both types of contamination fear.
These findings support the hypothesis that mental and contact contamination are related but separable constructs.

Mental contamination and its relationship with OCD symptoms:

Mental contamination scores were positively correlated with OCD symptom severity in both studies.
People with higher levels of mental contamination had higher OCD symptoms.

Mental contamination and its relationship with thought-action fusion beliefs:

Thought-action fusion beliefs refer to the idea that having an unacceptable thought is equivalent to carrying out the unacceptable action, or that thinking about an event makes it more likely to actually happen.

People with greater mental contamination reported higher thought-action fusion beliefs.
Mental contamination scores were positively correlated with thought-action fusion beliefs in Study 1.
In Study 2, mental contamination scores were associated with contamination-related thought-action fusion beliefs.

Mental contamination and its relationship with negative affect:

In Study 2, correlations between mental contamination and psychopathology remained significant even after controlling for general negative affect.
There were no differences in negative affect scores between people with and without mental contamination.
These results suggest mental contamination is related to but separable from general negative affect.

Insight

This research provides the first systematic evidence that mental contamination is a familiar problem for many people with OCD. The high rates of mental contamination found here contrast with the theory that contact contamination is more common.

The association between mental contamination and psychopathology variables, even when controlling for general negative affect, supports mental contamination as a distinct phenomenon requiring tailored treatment rather than just a symptom of low mood.

The finding that mental and contact contamination are related but separable constructs provides empirical backing for Rachman’s theory.

However, further research with larger and more diverse clinical samples is needed to establish mental contamination as clinically relevant across OCD presentations.

Overall, these findings pave the way for a better understanding of mental contamination in OCD and optimizing psychological treatment approaches.

Strengths

Used multiple standardized measures with good psychometric properties
Included some diagnostic confirmation of OCD
Examined relationships between mental contamination and psychopathology
Controlled for general negative affect
Sample recruited from diverse clinical sources

Limitations

Self-selected sample may limit generalizability
Under-representation of certain OCD symptoms
No comparison clinical group
No investigation of disgust or other variables
Questionnaire reliance limits insight into symptoms

Implications

This research highlights mental contamination as an important clinical phenomenon in OCD that may benefit from tailored treatment approaches. The findings support mental contamination as partially distinct from contact contamination and mood difficulties.

If substantiated in further studies, these results suggest mental contamination should be routinely assessed in OCD assessments. More research is needed regarding variables influencing contamination symptom profiles and presence across disorders.

Clinically, directly addressing feelings of internal dirtiness not contingent on physical contact may enhance OCD treatment outcomes when mental contamination is present.

References

Primary reference

Coughtrey, A. E., Shafran, R., Knibbs, D., & Rachman, S. J. (2012). Mental contamination in obsessive–compulsive disorder. Journal of Obsessive-Compulsive and Related Disorders, 1(4), 244-250. https://doi.org/10.1016/j.jocrd.2012.07.006

Other references

Cougle, J.R., Lee, H.J., Horowitz, J.D., Wolitzky-Taylor, K.B., & Telch, M.J. (2008). An exploration of the relationship between mental pollution and OCD symptoms. Journal of Behaviour Therapy and Experimental Psychiatry, 39, 340-353.

Fairbrother, N., & Rachman, S.J. (2004). Feelings of mental pollution subsequent to sexual assault. Behaviour Research and Therapy, 42, 173-190.

Rachman, S.J. (2006). The fear of contamination: Assessment and treatment. Oxford: Oxford University Press.

Radomsky, A.S, Rachman, S.J., Elliot, C., & Shafran, R. (submitted). Mental contamination: Development of measures. Manuscript submitted for publication.

Keep Learning

How might the treatment of OCD be improved based on these research findings regarding mental contamination? What questions remain?
If mental and contact contamination are related but distinct constructs, what factors might explain why some people experience both while others only have one contamination fear?
What are some ethical considerations regarding recruiting and studying clinical samples that experience significant distress related to their symptoms? How might this impact the methodology and generalizability of the research?
Why might a better understanding of mental contamination be relevant not only for OCD treatment but also for conditions like PTSD? What comparisons or links might be interesting to study further?

Mental Contamination in OCD: A Systematic Review