Delusional infestation: treatment outcome with antipsychotics in 17 consecutive patients (using standardized...

The multietiological nature of delusional infestation (DI) implies that therapy needs to be customized according to the various forms of DI (primary/secondary). Usually, treatment of DI is difficult to achieve in psychiatric settings because of the patients' nonpsychiatric concept of the illness.

We analyzed the data of all consecutive DI patients seen in the Psychiatric Outpatient Department of the General Hospital Bruneck/Italy from 1998 to 2010, including structural brain imaging findings. Standardized reporting criteria are applied for the presentation of the cases in a naturalistic setting.

Our sample consisted of 17 patients. Notably, 15 out of these 17 patients (88%) could be engaged in an antipsychotic treatment trial. With different, mainly second-generation antipsychotics, all but one patient profited from antipsychotics, at least after substances were changed: 12 (71%) of the cases reached full remission, and another 2 (12%) had partial remission. The average duration of treatment was remarkably long: 3.8 years. Eight cases were classified as secondary to a brain disorder or medical condition, four cases were classified as secondary to psychiatric disorders and five cases fulfilled the criteria for primary DI (i.e., delusional disorder somatic type). All cases secondary to a brain disorder/medical condition showed macroscopic brain lesions mainly in the basal ganglia.

Our study confirmed previous experience that an excellent clinical outcome can be achieved in unselected patients with different DI forms provided that patients can be engaged in antipsychotic treatment. Although studies in DI are difficult to conduct, randomized controlled trials would be desirable to evaluate specific antipsychotic medication in DI in general and in the different forms of DI. More sophisticated investigations (single photon emission computed tomography and positron emission tomography) than structural brain imaging (magnetic resonance imaging and computed tomography) are needed to better elucidate underlying brain dysfunction in DI.