Efficacy and safety of quetiapine treatment for delusional parasitosis: experience in an elderly patient

Delusional infestation in clinical practice over a period of two decades

Introduction

Patients presenting with cutaneous symptomatology may in fact suffer from underlying psychiatric conditions. Individuals diagnosed with delusional infestation (DI) have a fixed false belief of being infested with certain organisms or objects.

Aim

To analyse clinical features of subjects with DI who were admitted to the tertiary dermatology ward.

Material and methods

A retrospective analysis concerning DI patients hospitalized between 1997 and 2019 was carried out. The emphasis was put on the duration of symptoms, psychiatric symptomatology (including the "specimen sign"), comorbidities as well as therapy.

Results

We gathered data regarding 21 consecutive patients with DI. The mean age of subjects was 65.2 ±13.3 years, the majority were females (76.2%). The mean time span between the disease onset and diagnosis was 1.9 ±1.7 years. Previous psychiatric consultations were attended by 57.0% of patients. The specimen sign was present in 47.6% of cases, whereas the most common suspected causative factors were described as worms (52.4%), unspecified parasites (42.9%), "something" (33.3%) and flies (19.0%). Primary delusional disorder was diagnosed in 76.2%, followed by shared delusional disorder and secondary delusional disorder of organic origin (9.5% each). Risperidone monotherapy was initiated in 61.9% of patients. In total, only 33.3% of patients attended the follow-up visit.

Conclusions

DI features a wide spectrum of clinical signs and symptoms. Risperidone remains the drug of choice in the majority of cases. Successful management of each DI case requires collaboration between dermatologists and psychiatrists and still remains a major challenge.

A systematic review of antipsychotic agents for primary delusional infestation

BACKGROUND

Delusional infestation (DI) is a rare delusional disorder in which individuals have a false belief that they are infested with bugs, parasites, or insects, despite the lack of medical evidence that such an infestation exists. Data on the effectiveness of antipsychotics for DI are limited.

METHODS

We conducted a systematic review using EMBASE, MEDLINE, PsycINFO, and Cochrane Central Register of Controlled Trials from inception of the databases up until July 20, 2018. Studies examining typical or atypical antipsychotics for primary DI were included.

RESULTS

A total of 51 relevant articles were identified, primarily case reports/series. Overall response was favorable for both typical and atypical antipsychotics, but there was no strong evidence to suggest that any one antipsychotic agent was preferable to other agents. Pimozide (1-16 mg/day) and risperidone (0.5-8 mg/day) were the most commonly studied typical and atypical antipsychotics, respectively. Inconsistent reporting of treatment outcomes and variability in study designs limited the overall evaluation of the data.

CONCLUSIONS

There remains a lack of sound data supporting the effectiveness of antipsychotic treatment for primary DI. Further research is required to establish more definitive conclusions about the relative clinical utility of antipsychotic agents for DI.

Delusional infestation: the case for improved mental state testing

OBJECTIVES

Delusional infestation may present as a primary disorder or secondary to another disorder (e.g. schizophrenia). In this report we focus on the issue of inadequacies in mental state examinations leading to diagnostic uncertainty.

METHODS

Case studies were identified for this review through searching the academic databases MedLine, PSYCInfo and PubMed. We developed a template that contained 36 headings and independently examined each case study report. Our percentage agreement for the first 42 case studies we reviewed was 91%.

RESULTS

We identified diagnostic uncertainty due to inadequacies in the reporting of mental state examinations.

CONCLUSIONS

Clinicians need to provide mental state information to an adequate standard that would allow confirmation of a diagnosis of delusions of infestation or exclude other possibilities.

Successful ziprasidone monotherapy in a case of delusional parasitosis: a one-year followup

Delusional parasitosis is characterized by the false idea that own body is infested by invisible mites, insects, or other parasites. This case report describes a 24-year-old woman with delusional parasitosis who was treated with ziprasidone monotherapy (120 mg/day) with a complete remission of delusion and followed for one year without symptom recurrences. These findings, although preliminary, indicate that further investigation of ziprasidone monotherapy for the treatment of delusional parasitosis is warranted in further trials.

Delusional infestation

This papers aims at familiarizing psychiatric and nonpsychiatric readers with delusional infestation (DI), also known as delusional parasitosis. It is characterized by the fixed belief of being infested with pathogens against all medical evidence. DI is no single disorder but can occur as a delusional disorder of the somatic type (primary DI) or secondary to numerous other conditions. A set of minimal diagnostic criteria and a classification are provided. Patients with DI pose a truly interdisciplinary problem to the medical system. They avoid psychiatrists and consult dermatologists, microbiologists, or general practitioners but often lose faith in professional medicine. Epidemiology and history suggest that the imaginary pathogens change constantly, while the delusional theme "infestation" is stable and ubiquitous. Patients with self-diagnosed "Morgellons disease" can be seen as a variation of this delusional theme. For clinicians, clinical pathways for efficient diagnostics and etiology-specific treatment are provided. Specialized outpatient clinics in dermatology with a liaison psychiatrist are theoretically best placed to provide care. The most intricate problem is to engage patients in psychiatric therapy. In primary DI, antipsychotics are the treatment of choice, according to limited but sufficient evidence. Pimozide is no longer the treatment of choice for reasons of drug safety. Future research should focus on pathophysiology and the neural basis of DI, as well as on conclusive clinical trials, which are widely lacking. Innovative approaches will be needed, since otherwise patients are unlikely to adhere to any study protocol.