Paroxetine therapy for somatic delusion – Implications for underlying serotonergic dysfunction

To the Editor

Delusional disorder, somatic type (DDST) is characterized by hypochondriacal delusions. Pimozide is recommended as the first-choice drug for this disorder (Munro, 1988). However, there have been reports that tricyclic antidepressants are effective (Hayashi et al., 2004), suggesting serotonergic dysfunction. There is, therefore, a case for selective serotonin reuptake inhibitors (SSRIs) to be considered as treatment options for this disorder. We present a case of successful management of such a patient with paroxetine.

A 32-year-old male presented with an 8-year history of a belief that his head has become numb from the inside and his brain’s vessels have become blocked. He stopped pouring water over his head while bathing and started wearing a scarf over his head always as he believed that water/cold air could make his head more blocked. He had previously been treated with first-generation antipsychotics. His mental status examination revealed somatic delusion, while other domains of mental state showed no abnormality. Physical examination, relevant hematological tests, magnetic resonance imaging (MRI) of the brain and electroencephalogram (EEG) did not reveal any abnormality.

The patient was initially treated with olanzapine 20 mg/day for 4 weeks, but he continued to maintain his belief with the same intensity. The olanzapine was stopped and the patient was subsequently treated with paroxetine 25 mg/day, and the dose was gradually increased to 37.5 mg/day on the second week. About 10 days later, it was observed that he stopped wearing scarf overhead and started to pour water over his head while bathing. Three weeks later, he reported that the ‘block’ was much minimized and he maintained the improvement till 1 year of follow-up.

Pimozide is reported as a first-choice drug for DDST, but it has serious cardiovascular side effects like QTc prolongation. Earlier research has suggested that DDST is related to serotonergic dysfunction as there is reported efficacy of tricyclic antidepressants for the treatment (Hayashi et al., 2004). However, paroxetine holds a safer side effect profile, for example, fewer anticholinergic effects and a lower incidence of cessation due to adverse events compared to tricyclics (Wagstaff et al., 2002). Hayashi et al. (2004) also reported successful use of paroxetine in a case with DDST and suggested that paroxetine normalizes hypoperfusion in the left temporal and parietal lobes.

In conclusion, this report suggests that paroxetine may be an effective treatment option for ‘DDST’ and supports the previous views that DDST is associated with serotonergic dysfunction.