PANDAS: Too Narrow a View of the Neuroimmune Landscape

Abrupt onset or exacerbation of anorexia nervosa following recent infections: a mini-review and a case report with an atypical manifestation of PANS

PURPOSE

This study examines the connection between infections and the abrupt onset or exacerbation of anorexia nervosa (AN) in the context of PANS (Pediatric Acute-Onset Neuropsychiatric Syndrome) and PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections).

METHODS

The authors conducted a literature review and present a case study of a 17-year-old girl treated at the University of Turin Eating Disorder Unit, whose AN presented with an abrupt onset following an infection and was characterized by a rapid and favorable course.

RESULTS

The review includes 30 cases derived from six studies, suggesting that AN can manifest as PANS/PANDAS, with subjects, mainly adolescents, experiencing sudden or exacerbated eating restrictions alongside obsessive-compulsive behaviors. Some cases improved with antibiotics or standard psychiatric treatments, although age, symptom severity, and diagnostic markers like D8/17 varied across studies. Data on treatment follow-up also varied. The report refers to the case of V., a 17-year-old girl who developed AN following an intestinal infection. After significant weight loss and amenorrhea, she was hospitalized for 29 days, receiving psychiatric care, nutritional rehabilitation, and pharmacological treatment. Over 2 months of residential care and ongoing outpatient therapy, she improved notably, though mild body dysmorphophobia persisted.

CONCLUSIONS

While evidence suggests a possible link between infections and AN, research is still limited and inconsistent. Infections may trigger AN through autoimmune mechanisms or by initiating weight loss, particularly in younger patients. Although further studies are needed to clarify this relationship, infections should be considered in AN diagnosis, especially in pediatric cases.

LEVEL OF EVIDENCE

Level V, a narrative review and a case report.

Gut microbiota changes are associated with abnormal metabolism activity in children and adolescents with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a chronic and disabling psychiatric disorder characterized by recurrent intrusive thoughts or repetitive behaviors. We sought to better understand the structure of gut microbiota in first visit registration, treatment-naive children and adolescents with OCD, and the relationship between gut microbiota and fecal metabolites. Thus we studied the gut microbial population using 16 S rRNA sequencing in 49 children (8-17 years of age) with OCD, 42 healthy controls (HCs). We found a significant decrease in α-diversity in the OCD group, and the OCD and HC groups had distinctive intestinal flora. To further investigate the potential interaction effects between OCD and functional pathways of the intestinal flora, the 19 OCD patients and 18 aged-matched HCs were selected to undergo metagenomics analysis. We showed that several functional pathways of gut microbiota in patients with OCD were disrupted, such as glucolipid metabolism, amino acid metabolism, steroid biosynthesis, and the second messenger system. Changes in the clinical characteristics of OCD patients were associated with specific bacteria. Metabolomics analysis was also performed on stool samples from 91 subjects. Intestinal microflora metabolite expression in OCD patients was disturbed, and the related metabolic pathway functions were abnormal. Abnormal metabolites of gut microbiota in OCD patients are mainly involved in folate biosynthesis, the prion disease pathway, and the amino acid metabolic network. This study detailed the intestinal microbiota of children and adolescents with OCD. Our study suggests possible modalities for early OCD intervention by targeting the specific bacteria associated with neurotransmitter metabolism.

Ultrarare Variants in DNA Damage Repair Genes in Pediatric Acute-Onset Neuropsychiatric Syndrome or Acute Behavioral Regression in Neurodevelopmental Disorders

INTRODUCTION

Acute onset of severe psychiatric symptoms or regression may occur in children with premorbid neurodevelopmental disorders, although typically developing children can also be affected. Infections or other stressors are likely triggers. The underlying causes are unclear, but a current hypothesis suggests the convergence of genes that influence neuronal and immunological function. We previously identified 11 genes in pediatric acute-onset neuropsychiatric syndrome (PANS), in which two classes of genes related to either synaptic function or the immune system were found. Among the latter, three affect the DNA damage response (DDR): PPM1D, CHK2, and RAG1. We now report an additional 17 cases with mutations in PPM1D and other DDR genes in patients with acute onset of psychiatric symptoms and/or regression that their clinicians classified as PANS or another inflammatory brain condition.

METHODS

We analyzed genetic findings obtained from parents and carried out whole-exome sequencing on a total of 17 cases, which included 3 sibling pairs and a family with 4 affected children.

RESULTS

The DDR genes include clusters affecting p53 DNA repair (PPM1D, ATM, ATR, 53BP1, and RMRP), and the Fanconi Anemia Complex (FANCE, SLX4/FANCP, FANCA, FANCI, and FANCC). We hypothesize that defects in DNA repair genes, in the context of infection or other stressors, could contribute to decompensated states through an increase in genomic instability with a concomitant accumulation of cytosolic DNA in immune cells triggering DNA sensors, such as cGAS-STING and AIM2 inflammasomes, as well as central deficits on neuroplasticity. In addition, increased senescence and defective apoptosis affecting immunological responses could be playing a role.

CONCLUSION

These compelling preliminary findings motivate further genetic and functional characterization as the downstream impact of DDR deficits may point to novel treatment strategies.

PANDAS: Twenty-Five Years Later

Background:

It has been 25 years since the definition of the concept of Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS). The abrupt onset of neuropsychiatric symptoms requires a comprehensive differential diagnosis involving complementary tests and optimal treatment selection.

Methods:

This paper describes aspects related to the diagnosis and clinical management of PANDAS. A clinical perspective is developed starting from an example that meets the Swedo's criteria.

Discussion:

A comprehensive approach, including interdisciplinary management and urgent evaluation of potential organic causes, is crucial for effective treatment. Treatment decisions should consider severity, symptoms, and available evidence. Collaboration with neuropediatric or neurological services is needed. ASLO/anti-DNase B and 25-OH-Vitamin D tests are valuable for atypical OCD/Tic presentations, always maintaining a broader organic screening.

Efficacy of Antidopaminergic Pharmacotherapy in Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infections (PANDAS): A Case Report

PANDAS, or pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections, is a neuropsychiatric disease seen in children that presents with prevailing symptoms of obsessive-compulsive disorder (OCD), tic disorder, or both. These symptoms appear suddenly following a streptococcal infection, such as strep throat or scarlet fever. The antibodies formed to eradicate the streptococcal infection have been shown to alter central dopamine signaling. In spite of being acknowledged in the medical community for the last two to three decades, PANDAS is a disorder that goes unnoticed by many healthcare professionals. Unfortunately, even with correct diagnosis and utilization of commonly prescribed pharmacotherapy and psychotherapy, medical management can often be ineffective at treating the neuropsychiatric symptoms. Here, we describe a case of a 15-year-old male who presented to the primary care office with complaints of episodic behavioral changes that would occur multiple times daily. The general symptoms were centered around body dysmorphia where the patient became obsessed with fixed portions of food and became highly focused on only specific food types. The symptoms would exacerbate and progress with a dire need to burn calories, leading the patient to damage carpeted areas in the home due to regular and fanatical pacing. The patient underwent trials with serotonergic pharmacotherapy with little to no relief of the psychiatric symptoms. After discussion with his primary care physician, the patient underwent trial management with antidopaminergic therapy that resulted in significant neurological and psychiatric improvement. The use of antidopaminergic pharmacotherapy to target the induction of D1 and D2 dopamine receptors was efficacious in this patient; however, it warrants additional research with a larger sample to determine its effectiveness in the treatment of this psychiatric condition.

Pediatric Acute-Onset Neuropsychiatric Syndrome: Current Perspectives

Pediatric acute-onset neuropsychiatric syndrome (PANS) features a heterogeneous constellation of acute obsessive-compulsive disorder (OCD), eating restriction, cognitive, behavioral and/or affective symptoms, often followed by a chronic course with cognitive deterioration. An immune-mediated etiology is advocated in which the CNS is hit by different pathogen-driven (auto)immune responses. This narrative review focused on recent clinical (ie, diagnostic criteria, pre-existing neurodevelopmental disorders, neuroimaging) and pathophysiological (ie, CSF, serum, genetic and autoimmune findings) aspects of PANS. We also summarized recent points to facilitate practitioners with the disease management. Relevant literature was obtained from PubMed database which included only English-written, full-text clinical studies, case reports, and reviews. Among a total of 1005 articles, 205 were pertinent to study inclusion. Expert opinions are converging on PANS as the effect of post-infectious events or stressors leading to "brain inflammation", as it is well-established for anti-neuronal psychosis. Interestingly, differentiating PANS from either autoimmune encephalitides and Sydenham's chorea or from alleged "pure" psychiatric disorders (OCD, tics, Tourette's syndrome), reveals several overlaps and more analogies than differences. Our review highlights the need for a comprehensive algorithm to help both patients during their acute distressing phase and physicians during their treatment decision. A full agreement on the hierarchy of each therapeutical intervention is missing owing to the limited number of randomized controlled trials. The current approach to PANS treatment emphasizes immunomodulation/anti-inflammatory treatments in association with both psychotropic and cognitive-behavioral therapies, while antibiotics are suggested when an active bacterial infection is established. A dimensional view, taking into account the multifactorial origin of psychiatric disorders, should suggest neuro-inflammation as a possible shared substrate of different psychiatric phenotypes. Hence, PANS and PANS-related disorders should be considered as a conceptual framework describing the etiological and phenotypical complexity of many psychiatric disorders.

Immunological causes of obsessive-compulsive disorder: is it time for the concept of an "autoimmune OCD" subtype?

Obsessive-compulsive disorder (OCD) is a highly disabling mental illness that can be divided into frequent primary and rarer organic secondary forms. Its association with secondary autoimmune triggers was introduced through the discovery of Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infection (PANDAS) and Pediatric Acute onset Neuropsychiatric Syndrome (PANS). Autoimmune encephalitis and systemic autoimmune diseases or other autoimmune brain diseases, such as multiple sclerosis, have also been reported to sometimes present with obsessive-compulsive symptoms (OCS). Subgroups of patients with OCD show elevated proinflammatory cytokines and autoantibodies against targets that include the basal ganglia. In this conceptual review paper, the clinical manifestations, pathophysiological considerations, diagnostic investigations, and treatment approaches of immune-related secondary OCD are summarized. The novel concept of "autoimmune OCD" is proposed for a small subgroup of OCD patients, and clinical signs based on the PANDAS/PANS criteria and from recent experience with autoimmune encephalitis and autoimmune psychosis are suggested. Red flag signs for "autoimmune OCD" could include (sub)acute onset, unusual age of onset, atypical presentation of OCS with neuropsychiatric features (e.g., disproportionate cognitive deficits) or accompanying neurological symptoms (e.g., movement disorders), autonomic dysfunction, treatment resistance, associations of symptom onset with infections such as group A streptococcus, comorbid autoimmune diseases or malignancies. Clinical investigations may also reveal alterations such as increased levels of anti-basal ganglia or dopamine receptor antibodies or inflammatory changes in the basal ganglia in neuroimaging. Based on these red flag signs, the criteria for a possible, probable, and definite autoimmune OCD subtype are proposed.