Patient on Gabapentin develops Trypophobia- A case report

A patient on gabapentin reportedly developed trypophobia which was thankfully reversible. The case has been reported by Dr Robakis at Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA and has been published in the Journal of Clinical Psychopharmacology.

Trypophobia is fear of the sight of irregular patterns or clusters of small holes or bumps. It is not officially recognized as a mental disorder but may fall under the broad category of specific phobia if fear is involved and the fear is excessive and distressing. People may express only disgust or both fear and disgust to trypophobic imagery.

According to history, a 67-year-old woman was being treated with gabapentin 1800mg/day for paresthesia which had developed 5 years prior without any obvious triggers. While the treatment was effective, it led the patient to develop trypophobia, "a feeling of aversion or fear in response to visual images of arrays of small holes." She had reported fear associated with traffic lights (which led to driving impairment), certain television images (eg, insect eyes), shower heads, and pictures of lotus flowers.

The patient was started on duloxetine in order to reduce her dependence on gabapentin, and the trypophobia. During the periods when the patient was taking duloxetine monotherapy, trypophobia had been absent. Eventually, the patient was treated with duloxetine 30mg twice daily with supplemental doses of gabapentin 300mg/day as needed. At this dose, her trypophobia no longer interfered with her daily functioning. It should be noted that the patient had been treated with duloxetine 40mg 3 times daily, which led her to discontinue gabapentin entirely, but due to insurance coverage issues, the dose of duloxetine needed to be reduced.

It has been estimated that about 16% of the population is susceptible to this phobia. Based on the Naranjo Adverse Drug Reaction Probability Scale, this adverse event was found to be strongly linked to gabapentin (score of 8). The authors note that gabapentin is often used off-label to treat anxiety and social phobia, however in this patient, the effects were found to be paradoxical.

Future studies and case reports are needed in order to determine the limit between trypophobic discomfort as an aversive response and trypophobia as a clinically valid anxiety disorder.