Mental Contamination of Obsessive Compulsive Disorder OCD Treated with Cognitive Behavior Therapy-CBT

Hand washing

Case Study of Mental Contamination Obsessions

Mental contamination refers to a “phenomenon whereby people experience feelings of contamination from a non-physical contaminant” (Warnock-Parkes, Salkovskis, & Rachman, 2012, p. 383). A good many patients with obsessive-compulsive disorder (OCD) report this symptom. OCD affects between 1%-2.5% of the population, with contamination concerns and the related compulsion to wash excessively in a reported 38-50% of people diagnosed with the disorder (Torres et al., 2006; Rachman & Hodgson, 1980; Foa et al., 1995; Foa et al., 1998). Recently, a team of researchers shared valuable insights about the treatment of mental contamination with a single case study of a 40 year old male, by the alias of David, suffering from severe obsessions of mental contamination that resulted in a 20 year period of unemployment and restricted living (Warnock-Parkes et al., 2012).


Concerns with Contamination 

Interestingly, the researchers highlight the important connection between common contamination concerns and the contemporary culture in which they manifest. For example, contamination obsessions became much more common after the discovery of germs in the late 1800s and subsequently shifted to radiation concerns after World War II. More recently, contamination concerns are related to illnesses such as HIV/AIDS (Warnock-Parkes et al., 2012). The prevalence and severity of contamination based concerns heightens the necessity for clinicians to understand effective treatment strategies. Warnock-Parkes et al. (2012) glean their treatment strategy from Rachman’s 2006 and 2010 research studies into treatment differentiation for mental contamination versus other OCD symptoms.


Role of Emotions

Mental contamination concerns differ from contact contamination concerns (contamination obsessions about items that can contaminate) in terms of effective treatment. Mental contamination obsessions tend to induce more pervasive feelings of contamination and are typically connected to specific emotional reactions as well (Rachman, 2006). Rachman (2006) highlights the important theme of betrayal/violation often present for individuals suffering this symptom; this corresponds to the discrepancy between contamination-inducing subjects. Mental contamination is most often induced by a person or group of people than by a substance (Rachman, 2006).


Personal Events Affect Contamination Obsessions

In David’s case, feelings of contamination were induced by thinking about the government, brown envelopes, and his ex-wife. David’s history revealed that symptoms first started after a traumatic divorce with his ex-wife, an action taken after David found out his wife had cheated on him several times. He was taken to court for custody of their children and delivered frequent official government mail (in brown envelopes) including devastating materials such as divorce papers. David’s reports of feeling contaminated and “like rubbish” merely by thinking about the government or his ex-wife make much more sense within the context of his personal narrative. 


Treatment Approaches

Two different courses of action were attempted by Warnock-Parkes et al. (2012) during David’s treatment: high quality cognitive behavioral therapy (CBT) and cognitive therapy focused on mental contamination (CTMC). Before treatment, he was administered several assessment scales to measure OCD symptoms, anxiety and depression, work and social adjustment, and level on contamination subscale. First, David attended six sessions of high-quality CBT with a well regarded therapist, after which point he disengaged and reported not to have found the treatment helpful. David was then referred on to option two, CTMC, consisting of 13 sessions of treatment focused on seven key steps (Warnock-Parkes et al., 2012, p. 388):

1.      Extended assessment and formulation

2.      Psychoeducation and socialization to the mental contamination model

3.      Motivation to change and goal setting

4.      Cognitive work on key appraisals, including imagery re-scripting

5.      Behavioral experiments using exposure and response prevention therapy (ERP) and stimulus discrimination

6.      Reclaiming life following OCD

7.      Relapse prevention and booster sessions


Symptom Improvement

The result of CTMC for the treatment of David’s mental contamination concerns eliminated David’s reported excessive washing due to contamination obsessions. David also reported improved familial relationships and ability to tolerate mail/brown packages into his home. He was able to use local facilities that otherwise would have greatly concerned him for contamination, like government centers.


Tailored Cognitive Interventions

This case study is believed by the research team to accomplish several things. Chiefly, it accurately illustrates Rachman’s proposals about the necessity of addressing mental contamination by targeting the underlying and historical issues through a series of specifically tailored cognitive interventions such as imagery re-scripting (Warnock-Parkes et al., 2012). These interventions aim, over time, to affect how a patient appraises historical memories and current activators, or how he/she evaluates people or events that trigger said memories and activate the instinct to re-live emotional traumas. The researchers hope a more targeted treatment for those suffering from mental contamination will yield significant symptom reduction, greatly benefitting the large percentage of patients with OCD who currently drop out of treatment relatively early with little to no improvement.





Foa, E. B., Kozak, M. J., Goodman, W.K., Hollander, E., Jenike, M. A., & Rasmussen, S. A. (1995). DSM-IV field trial: Obsessive-compulsive disorder scale. American Journal of Psychiatry, 152(1), 90-96.


Foa, E. B., Kozak, M. J., Salkovskis, P. M., Coles, M. E., & Amir, N. (1998). The validation of a new obsessive-compulsive disorder scale: The Obsessive-Compulsive Inventory. Psychological Assessment, 10(3), 206-214.


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


Rachman, S. (2010). Betrayal: A psychological analysis. Behavior Research and Therapy, 48, 304-311.


Torres, A., Prince, M., Bebbington, P., Bhugra, D., Brugha, T., Farrell, M., et al. (2006). Obsessive-compulsive disorder: prevalence, comorbidity, impact, and help-seeking in the British National Psychiatric Morbidity Survey of 2000. American Journal of Psychiatry, 163, 1978-1985.


Warnock-Parkes, E., Salkovskis, P., Rachman, J. (2012). When the problem is beneath the surface in OCD: The cognitive treatment of a case of pure mental contamination. Behavioral and Cognitive Psychotherapy, 40, 383-399.


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