Guanfacine treatment for a patient with delusional parasitosis causing dermatillomania presenting with shared psychiatric disorders

Abstract

Dermatillomania often coexists with delusional parasitosis (DP) and can cause extreme patient morbidity. The standard treatment for DP has been conventional antipsychotic drugs; however, their use is limited by potential adverse effects and monitoring requirements. Guanfacine, an alpha-2 adrenergic receptor agonist, has emerged as a promising alternative for patients with attention deficit hyperactivity disorder with concurrent tics. Although no current research supports guanfacine’s efficacy in managing DP or dermatillomania, its pharmacological profile hints at potential benefits. A 58-year-old woman presented to our clinic for DP causing dermatillomania and was started on guanfacine. She reported fewer beliefs about parasites infesting her body and had fewer excoriating lesions on this medication. Additionally, her Patient Health Questionnaire-9 score peaked with a score of 23 at diagnosis and significantly decreased to 13 three months after starting guanfacine. However, further research is needed to ascertain if guanfacine is an effective treatment for DP.

CASE SUMMARY

A 58-year-old woman with a history of posttraumatic stress disorder (PTSD), opioid use disorder, borderline personality disorder, major depressive disorder, and trichotillomania presented fully convinced of a fungal and parasitic infestation in her body, vehemently rejecting any suggestion that her discomfort could be a delusion. Previously, she shared her struggles with compulsive behaviors, notably hair-pulling that left bald patches. To deter this behavior, she even shaved parts of her head.

A dermatological assessment identified hair density and diameter inconsistencies, particularly in the bitemporal region. Scabbed and excoriated papules were noted on her scalp and neck, and her feet exhibited scaly plaques occupying roughly 1% of her body surface area. Interestingly, her back was devoid of any rash during this assessment.

Her sensation of being infested had intensified and expanded beyond her scalp, escalating her concerns. In her latest consultation, she articulated a steadfast belief that she was continually being parasitized by bugs, which, she felt, resulted in blisters on various parts of her upper body. She observed these blisters, which would eventually itch and bleed, often correlating them with her seasonal allergies.

Given her complicated mental health history and the possibility of abnormal compulsive behaviors impacting her symptoms, a thorough evaluation was performed. Her delusions were acknowledged, and their profound negative impact on her well-being was recognized. Keeping in mind the authenticity of her experiences, the therapeutic approach was holistic, addressing the dermatological manifestations and the underlying psychological concerns. The patient was on venlafaxine for PTSD, trazodone for insomnia, suboxone for opioid use disorder, bupropion for her anxiety and major depressive disorder, and guanfacine long acting 1 mg orally daily for her trichotillomania. Impressively, within 3 months of starting guanfacine therapy, she reported a significant decline in her delusions of infestation and observed fewer lesions.

From a quantitative perspective, the patient’s baseline Patient Health Questionnaire (PHQ-9) was 9.67 (standard deviation, 1.67) 6 months prior to the diagnosis of DP, which escalated to 23 at the time of diagnosis, but showed considerable improvement after guanfacine treatment, settling at 13. General Anxiety Disorder (GAD-7) scores were fairly stable, recorded at 16 pretreatment and 17 posttreatment, which put her at a severe anxiety category at both timepoints. The World Health Organization Quality of Life-BREF (WHOQOL-BREF) scale painted an encouraging picture.¹ Pretreatment scores were 31, 31, 50, and 44 for physical health, psychological health, social relationships, and environment domains. Posttreatment scores exhibited a noticeable improvement in physical health, psychological health, and environmental domains, shifting to 50, 44, and 50. However, a minor dip was observed in her social relationships, settling at 44. Lower PHQ-9 and GAD-7 scores indicate improvement in symptoms, while the larger the WHOQOL-BREF scale, the better the symptoms.

CLINICAL QUESTIONS

1. A 15-year-old girl is diagnosed with attention deficit hyperactivity disorder (ADHD). To help manage her symptoms, her doctor prescribed guanfacine, an alpha-2 agonist. How does guanfacine’s mechanism of action compare to that of selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs)?

   1. Guanfacine increases the serotonin reuptake pump in presynaptic neurons. SSRIs inhibit 5-hydroxytryptamine (5-HT) and norepinephrine (NE) reuptake. SNRIs stimulate presynaptic α2-adrenergic receptors in the central nervous system (CNS).

   2. Guanfacine inhibits 5-HT and NE reuptake. SSRIs stimulate presynaptic α2-adrenergic receptors in the CNS. SNRIs decrease the serotonin reuptake pump in presynaptic neurons.

   3. Guanfacine stimulates presynaptic α2-adrenergic receptors in the CNS. SSRIs inhibit 5-HT and NE reuptake. SNRIs decrease the serotonin reuptake pump in presynaptic neurons.

   4. Guanfacine inhibits cyclic adenosine monophosphate dependent protein kinase (cAMP-PKA) opening of K + channels in prefrontal spines. SSRIs decrease the serotonin reuptake pump in presynaptic neurons. SNRIs inhibit 5-HT and NE reuptake.

2. A 58-year-old woman presents with a 2-month history of pruritic and excoriated papules on face, trunk, and extremities. She feels she has a bug infestation and constantly complains about “bugs crawling under her skin.” Physical examination, dermoscopy, and skin scrapings were negative for any infestation. Complete blood count, complete metabolic panel, and thyroid panel were unremarkable. The patient is adamant about getting treated for a bug infestation. Which of the following drugs would NOT be appropriate for treating this patient’s parasitosis delusions?

   1. Risperidone

   2. Ivermectin

   3. Pimozide

   4. Aripiprazole

DISCUSSION

Dermatillomania, often recognized as skin picking or excoriation disorder, manifests predominantly as scaly, erythematous, or ulcerated lesions due to relentless skin picking.² Dermatillomania has often been associated with obsessive-compulsive disorder, trichotillomania, body dysmorphic disorders, and anxiety.³ On a related note, delusional parasitosis (DP) is a relatively rare psychiatric disorder where patients are staunchly convinced of a parasitic infestation, even without medical evidence to support such beliefs.³ Notably, there exists an intersection of DP patients who display symptoms of dermatillomania, complete with excoriated lesions and consequential functional impairments.³ DP patients may exhibit obsessive-compulsive traits and may have comorbid depression, anxiety, or substance use disorders.³ A significant challenge in diagnosing DP arises from the stigma attached, causing patients to remain silent about their perceived infestations.

Presentation and diagnosis

DP is a delusional disorder in which the patient has a fixed, mistaken belief that they are infected with a parasite, worms, mites, germs, fungi, or other sorts of living creatures.³ Patients with underlying psychiatric disorders, such as chronic PTSD brought on by traumatic life experiences, may develop delusional views about being infested with bugs.⁴ Traumatic experiences can alter their perception of reality and safety and may make them more susceptible to developing trichotillomania and DP causing dermatillomania.⁴ Both trichotillomania and dermatillomania are commonly known as a hair-pulling disorder and a skin-picking disorder, respectively, and are obsessive behaviors that can cause extreme morbidity for patients that negatively impacts their quality of life.³

Management

Guanfacine, an alpha-2 adrenergic receptor agonist, has been used to treat ADHD by acting on catecholaminergic postsynaptic mechanisms.² Guanfacine has been demonstrated to be a reliable and secure therapy choice for ADHD in children and teenagers.⁵ Additionally, it has been proposed as a secure alternative therapy for children with ADHD who also exhibit tics; trichotillomania would fit this definition.^1,5 In an animal study, guanfacine led to a dose-dependent reduction in impulsive decision-making, increasing rats’ tolerance for delay in exchange for a larger reward.⁶ Guanfacine has shown promise in the treatment of impulse control problems in humans as well.⁷ In a case study of two patients with obsessive-compulsive disorder and ADHD, a combination of sertraline, a serotonin transporter inhibitor, and guanfacine, with cognitive behavioral therapy improved the patients’ symptoms.⁸

Traditional antipsychotic medications are typically used to treat DP, with pimozide being the drug of choice for dermatologists.^3,9 However, pimozide’s use is less practicable due to its undesirable side effects and the requirement for frequent electrocardiographic monitoring.⁹ Second-generation antipsychotics such as risperidone or olanzapine are also utilized as alternative therapies for DP but may also have significant side effects, including weight gain.⁹ Guanfacine may be considered for the treatment of dermatillomania if other treatment options do not prove to be successful or are not tolerated. Guanfacine’s adverse effects include dry mouth, sedation, lethargy, and headaches.⁵ Our patient’s symptoms improved after using guanfacine, but this result could also be attributed to a synergistic response with the other medications that the patient was prescribed. Although we suggest that treating DP with guanfacine may be a therapeutic option, further studies need to be carried out to validate this patient’s findings.

Evaluation

In this patient, guanfacine treatment was associated with a significant improvement in her insight of the disease (i.e., DP), total number of skin lesions, quality of life measures (WHOQOL scores generally increasing), and certain mental health scales (significant improvement in PHQ-9 score and no significant change in GAD-7 score). Even though guanfacine was prescribed for the patient’s trichotillomania, and not specifically for her skin symptoms, the incidentally observed findings highlight the possibility of guanfacine being a promising alternative treatment in DP-induced dermatillomania. The proposed mechanism is likely related to helping with impulse control, which has been seen in other conditions.^3–5

For the treatment of pruritus, pain, and other symptoms, corticosteroids, capsaicin, topical anesthetics, antihistamines, and immunomodulators are routinely utilized.⁴ Since there is a lack of data to support the efficacy of antipsychotic treatment for primary DP, we propose guanfacine to be a new potential treatment option for patients refractory to conventional treatment methods.

ANSWERS TO CLINICAL QUESTIONS

Question 1: d. Guanfacine is an alpha-2 agonist that prevents cAMP-PKA from activating K + channels in the prefrontal cortex.² This method of action increases prefrontal brain activity, which is thought to improve attention and impulsive control in ADHD patients.^2,10 SSRIs and SNRIs are antidepressants that are used off-label to treat ADHD.¹⁰ SSRIs inhibit serotonin reuptake, whereas SNRIs inhibit both serotonin and norepinephrine reuptake.¹⁰ SSRIs and SNRIs boost neurotransmitter availability in the synaptic cleft by reducing reuptake, which can improve mood and reduce anxiety.¹⁰ They do not, however, have the same immediate effect on attention and impulse control as guanfacine.^2,10 As a result, guanfacine and SSRIs/SNRIs work in various ways and are used for different purposes in the treatment of ADHD.^2,10

Question 2: b. DP is a psychiatric illness defined by the mistaken idea that one is parasitized.³ Second-generation antipsychotics, such as risperidone (a) and aripiprazole (d), are the mainstay of treatment.³ Pimozide (c) is a first-generation antipsychotic that can also be used but is not preferred due to safety concerns.³ Ivermectin is an antiparasitic agent; however, it does not treat the underlying cause of the disease, exposes patients to unnecessary possible side effects, and may help reinforce a patient’s delusion of being parasitized.¹¹

Disclosure statement

The authors report no funding or conflicts of interest. The patient gave permission to publish this case.