Successful Treatment of Delusional Disorder of the Somatic Type or “Delusional Parasitosis” with Olanzapine

Introduction

Delusional disorder of the somatic type is a rare psychiatric condition. It has also been called chronic tactile hallucinosis (where the primary problem is considered to be tactile hallucinations), delusional parasitosis or monosymptomatic hypochondriacal psychosis [2] [9] [12]. The patients have a false and fixed belief that they are infested with parasites [12]. DSM-IV describes delusional disorder as having non-bizarre delusions (i.e., involving situations that occur in real life, such as being followed, poisoned, infected, loved at a distance, or deceived by spouse or lover, or having a disease) for at least one month. Criterion A for schizophrenia has never been met although tactile and olfactory hallucinations may be present in delusional disorder if they are related to the delusional theme. The delusions cannot be due to the effects of substance abuse or a general medical condition. Subtypes are erotomanic, grandiose, jealous, persecutory, somatic, mixed and unspecified. When the same delusion develops in another individual, often a spouse, the disorder is called folie a deux [1].

Since the 1970s the treatment of choice has been the typical antipsychotic pimozide. There have been several case reports and studies that support this choice [5] [10] [11].

Recently there have been case reports stating the value of the atypical antypsychotics risperidone, olanzapine, and quetiapine [3] [4] [6] [7] [8] [11].

Lepping et al. tried to evaluate the usefulness of typical and atypical antipsychotics in delusional disorder, somatic type by conducting a systematic review. They concluded that both typical and atypical antipsychotics were effective in the majority, but that remission rates did not differ significantly. They suggest more rigorous studies to evaluate the effectiveness and to compare typical and atypical antipsychotics directly [7].

References

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• 8 Meehan WJ, Badreshia S, Mackley CL. Successful treatment of delusions of parasitosis with olanzapine.  Arch Dermatol. 2006;  142 352-355
• 9 Munro A. Monosymptomatic hypochondriacal psychosis manifesting as delusions of parasitosis.  Arch Dermatol. 1978;  114 940-943
• 10 Riding J, Munro A. Pimozide in the treatment of monosymptomatic hypochondriacal psychosis.  Acta Psychiatr Scand. 1975;  52 23-30
• 11 Wenning MT. et al . Atypical antipsychotics in the treatment of delusional parasitosisis.  Ann Clin Psychiatry. 2003;  15 233-239
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Correspondence