Boston – Patients with delusional infestation often resist referral to a psychiatrist and insist on treatment by a dermatologist, according to Mark D. P. Davis, MD.
Dermatologists, conversely, often don’t want to treat these challenging patients because they aren’t really sure how to manage them, Dr. Davis said during a “practice gaps” session at the American Academy of Dermatology summer meeting.
Dr. Mark Davis
An important practice gap is the lack of a standard approach to the investigation and management of these patients, he said.
An audience poll showed that respondents were divided as to whether patients presenting with delusional infestation, also known as delusional parasitosis, should be confronted, referred to a psychiatrist, treated with an antipsychotic, or approached in some other way.
The condition, which involves the delusional belief that one’s skin is “infested” with parasites, fibers, or some other materials, can result from another cause, said Dr. Davis of the Mayo Clinic, Rochester, Minn, noting that anxiety, depression, and medications such as opioids or treatments for attention deficit/hyperactivity disorder can contribute to the delusions.
Skin diseases themselves can also cause the sensation of infestation.
A good history should assess medical comorbidities, electrolyte abnormalities, or medication use that might be contributing to the problem.
For dermatologists who are not well-versed in “picking up on psychiatric comorbidities,” validated measures can be useful. Tools such as the Personal Health Questionnaire (PHQ)-9 for depression and Generalized Anxiety Disorder (GAD)-7 can be useful, Dr. Davis said.
However, delusions, by definition, are “fixed false beliefs.” Challenging a patient regarding their delusions is likely pointless, as the patients’ minds cannot be changed.
For cases of primary delusional infestation, the goal generally is to decrease the patient’s preoccupation with the delusion and to improve social and occupational functions. Treatment with antipsychotic drugs is usually helpful–if patients will comply with treatment. “I’ve been very unsuccessful” at getting patients to use antipsychotics, he said.
A good treatment option is risperidone, which has low cost and good efficacy and tolerability. Start with a daily dose of 1 mg/day and gradually increase up to 6 mg daily if necessary, he said.
Establishing a rapport over multiple visits may help with compliance. For example, take a history on the first visit, order laboratory tests at a second visit, perform a biopsy at a third, and then broach the subject of treatment at a subsequent visit, he suggested.
Getting the patient on board with taking risperidone or another antipsychotic may be easier if you ask the patient early on whether they would like treatment for their symptoms in the event a definitive cause for their symptoms can’t be identified, he said.
Dr. Davis reported having no disclosures.