Psychology and Psychiatry in the Dermatologist's Office: An Approach to Delusions of Parasitosis
April 2012 | Volume 11 | Issue 4 | Feature | 543 | Copyright © 2012
David Schairer BA, Laura Schairer BA, Adam Friedman MD
Most dermatologists will treat at least one patient suffering from delusions of parasitosis (DP) in their career.1 These patients are memorable not only for the peculiarity of their delusions and their repeated visits to the office, but for the challenges they present in their treatment. These patients are also frustrating. It seems that if they could only stop scratching, picking and manipulating their skin their symptoms would improve. However, these cutaneous signs only hint at the underlying psychiatric problem that drives these patients to manipulate their skin. These patients seek out the assistance of dermatologists and eschew the help of psychiatrists or therapists because they believe that they have a primary skin disease. Although the treatment of DP is conceptually simple, it is not intuitive. Thus as dermatologists, we should have at the ready a full set of dermatologic, psychologic, and pharmacologic tools to treat these patients.
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A diagnosis of DP can be quite evident on initial presentation—patients often directly and firmly state their delusions; he or she may bring in a plastic bag of evidence, or admit he or she has already consulted specialists regarding an infestation. However, the diagnosis of DP is one of exclusion and thus evaluation should first focus on ruling out medical causes of a patient's symptoms (for further information see Freudenmann et. al 2 ). A thorough investigation also builds up the patient's trust in the physician and acknowledges that the patient's problems are valid and worth treating. 3 While evaluating the symptoms, it is important to avoid statements that may hinder future treatment. When discussing any laboratory tests with the patient, it is important not to frame them as tests for parasites and validate the patient's delusion. Rather, frame them as tests for their symptoms, eg, "This blood test may reveal the cause of your itch." While it is important to not validate the delusion, contradicting the delusion will create tension between the physician and the patient. If the patient brings in "specimens" to be examined, each item should be carefully looked at with the patient and clearly named. Again, avoid statements such as "there is no evidence of parasites here," which directly contradict the patient's delusion. Gaining the patient's trust during the first few visits is crucial to treating the underlying psychiatric problem.
DP may be associated with specific behaviors, medical problems and psychiatric diseases. A thorough history may reveal that the symptoms began following an episode of contact dermatitis, a true arthropod bite, starting a new medication, consuming an illicit drug, or experiencing a recent psychosocial stressor. Patients can induce an irritant or contact dermatitis by using disinfectants, by using insecticides or washing excessively. They may report that they constantly itch and scratch or that they are using metal instruments to extract the parasites from their skin. Besides these activities which may cause skin lesions, it is important to elicit signs of other psychiatric conditions such as schizophrenia, paranoid states, bipolar disorder, depression, anxiety disorders, obsessional disorders, and suicidality as these are associated with and may cause DP.4,5 Finally, find out what is most distressing to the patient, whether it is the itching, the sensation of bugs crawling under their skin, the long rituals that interfere with their functioning, or the frustration from no one believing what they are saying.
After taking the history, examining the skin, and ordering tests, the next step is to approach the subject of psychiatric referral with a patient. This is a delicate process and should be done very carefully, as the rapport established thus far may be easily broken. Rather than pointing to the negative lab results and telling the patient that he or she must be wrong about the infestation, the subject of psychiatric referral can instead be approached as a possible adjunctive treatment to dermatological care.5 If the patient mentions any recent psychosocial stressors during the interview, this can be used as a starting place to suggest that, in addition to continuing dermatologic care, he or she may want to talk to a mental health professional about the stressful problems in his or her life, or about the impact of the stress of these symptoms.
Another potential source of referral may be to a psychologist. Although this option is not traditionally referred to in the dermatological literature on DP, psychological interventions have been found to be effective in reducing symptoms of psychosis interventions