PANDAS: current status and directions for research

The recognition of the five criteria for PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) by Swedo et al established a homogenous subgroup of children with childhood onset obsessive-compulsive disorder (OCD) and/or tic disorders. The five clinical characteristics that define the PANDAS subgroup are the presence of OCD and/or tic disorder, prepubertal age of onset, abrupt onset and relapsing-remitting symptom course, association with neurological abnormalities during exacerbations (adventitious movements or motoric hyperactivity), and a temporal association between symptom exacerbations and a Group-A beta-hemolytic streptococcal (GAS) infection. These five criteria have been used for the purpose of systematic research on the phenomenology and unique therapies for the PANDAS subgroup as well as studies of the pathophysiology of post-streptococcal OCD and tic disorders. The etiology of OCD and tics in the PANDAS subgroup is unknown, but is theorized to occur as a result of post-streptococcal autoimmunity in a manner similar to that of Sydenham's chorea. The working hypothesis for the pathophysiology begins with a GAS infection in a susceptible host that incites the production of antibodies to GAS that crossreact with the cellular components of the basal ganglia, particularly in the caudate nucleus and putamen. The obsessions, compulsions, tics, and other neuropsychiatric symptoms seen in these children are postulated to arise from an interaction of these antibodies with neurons of the basal ganglia.     

A pilot study of penicillin prophylaxis for neuropsychiatric exacerbations triggered by streptococcal infections.

BACKGROUND: Some children with obsessive-compulsive disorder (OCD) and tic disorders appear to have symptom exacerbations triggered by group A beta-hemolytic streptococcal infections in a manner that is similar to rheumatic fever and its neurologic variant, Sydenham's chorea. Because penicillin prophylaxis has proven to be effective in preventing recurrences of rheumatic fever, it was postulated that it might also prevent streptococcal-triggered neuropsychiatric symptom exacerbations in children with Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS). These children are identified by five clinical characteristics: presence of OCD or tic disorder, prepubertal onset, episodic symptom course, neurologic abnormalities (i.e., choreiform movements) and streptococcal-triggered symptom exacerbations. METHODS: Thirty-seven children with PANDAS were enrolled in an 8 month, double-blind, balanced cross-over study. Patients were randomized to receive either 4 months of the active compound (twice daily oral 250 mg penicillin V) followed by 4 months of placebo, or placebo followed by penicillin V. Tic, OCD, and other psychiatric symptoms were monitored monthly. Throat cultures and streptococcal antibody titers were also obtained. RESULTS: There were an equal number of infections in both the active and placebo phases of the study. There was no significant change seen in either the obsessive-compulsive or tic symptom severity between the two phases. CONCLUSIONS: Because of the failure to achieve an acceptable level of streptococcal prophylaxis, no conclusions can be drawn from this study regarding the efficacy of penicillin prophylaxis in preventing tic or OCD symptom exacerbations. Future studies should employ a more effective prophylactic agent, and include a larger sample size.     

The PANDAS subgroup of tic disorders and childhood-onset obsessive–compulsive disorder

Diagnosis and treatment of the PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) variant of Gilles de la Tourette syndrome (GTS) and childhood-onset obsessive–compulsive disorder (OCD) are still controversial issues. Most cross-sectional studies confirm a significant association between GTS and the development of an immune response against group A β-hemolytic streptococcus (GABHS). Moreover, longitudinal retrospective studies suggest that a recent exposure to GABHS might be a risk factor for the onset of tics and obsessive–compulsive symptoms. However, further evidence from longitudinal prospective research is needed to verify whether a temporal association between GABHS infections and symptom exacerbations is a useful and reliable criterion for the diagnosis of PANDAS. In addition, preliminary results suggest that the PANDAS spectrum might be enlarged to include attention deficit/hyperactivity disorder.Although a number of immunological biomarkers have been proposed as markers of the PANDAS variant, at present, none of these has been conclusively proved useful to diagnose and monitor disease course in children with a suspicion of PANDAS.Finally, despite their empirical use in community settings, we still lack conclusive, evidence-based data regarding the usefulness of antibiotic and immunomodulatory treatments in children with PANDAS. Given the relevance of this topic for general pediatric health, additional research efforts to solve all the pending issues and the hottest points of debate are warranted.     

The PANDAS subgroup of tic disorders and childhood-onset obsessive–compulsive disorder

Diagnosis and treatment of the PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) variant of Gilles de la Tourette syndrome (GTS) and childhood-onset obsessive–compulsive disorder (OCD) are still controversial issues. Most cross-sectional studies confirm a significant association between GTS and the development of an immune response against group A β-hemolytic streptococcus (GABHS). Moreover, longitudinal retrospective studies suggest that a recent exposure to GABHS might be a risk factor for the onset of tics and obsessive–compulsive symptoms. However, further evidence from longitudinal prospective research is needed to verify whether a temporal association between GABHS infections and symptom exacerbations is a useful and reliable criterion for the diagnosis of PANDAS. In addition, preliminary results suggest that the PANDAS spectrum might be enlarged to include attention deficit/hyperactivity disorder.Although a number of immunological biomarkers have been proposed as markers of the PANDAS variant, at present, none of these has been conclusively proved useful to diagnose and monitor disease course in children with a suspicion of PANDAS.Finally, despite their empirical use in community settings, we still lack conclusive, evidence-based data regarding the usefulness of antibiotic and immunomodulatory treatments in children with PANDAS. Given the relevance of this topic for general pediatric health, additional research efforts to solve all the pending issues and the hottest points of debate are warranted.     

Antibiotic prophylaxis with azithromycin or penicillin for childhood-onset neuropsychiatric disorders.

BACKGROUND: The acronym PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) describes a subgroup of children with obsessive-compulsive disorder and/or tic disorder that experience symptom exacerbations following streptococcal infections. We hypothesized that the prevention of streptococcal infections among children in the PANDAS subgroup would decrease neuropsychiatric symptom exacerbations. METHODS: Twenty-three subjects with PANDAS were enrolled in a double blind, randomized controlled trial. Antibiotic prophylaxis with penicillin or azithromycin was administered for 12 months. Rates of streptococcal infections and neuropsychiatric symptom exacerbations were compared between the study year and the baseline year prior to entry. RESULTS: Significant decreases in streptococcal infections during the study year were found with a mean of .1 (.3 SD) per subject, compared to the baseline year with 1.9 (1.2 SD) in the penicillin group and 2.4 (1.1 SD) in the azithromycin group [p<.01]. Significant decreases in neuropsychiatric exacerbations during the study year were also found with a mean of .5 (.5 SD) per subject in the penicillin group and .8 (.6 SD) in the azithromycin group, compared to the baseline year with 2.0 (.9 SD) in the penicillin group and 1.8 (.6 SD) in the azithromycin group [p<.01]. CONCLUSIONS: Penicillin and azithromycin prophylaxis were found to be effective in decreasing streptococcal infections and neuropsychiatric symptom exacerbations among children in the PANDAS subgroup.     

Is parental report of upper respiratory infection at the onset of obsessive-compulsive disorder suggestive of pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection?

The diagnosis of pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection (PANDAS) requires a prospectively determined association between group A beta-hemolytic streptococcal (GABHS) infection and obsessive-compulsive disorder (OCD) or tic disorder. Screening for GABHS infection imposes a significant burden on both patient and clinician. To heighten the index of suspicion for PANDAS, it would be useful to know if parent-reported upper respiratory infection (URI) is associated with PANDAS symptoms or associated characteristics. Eighty-three consecutive, clinically referred patients aged 6 to 17 years with a primary diagnosis of OCD and their primary caregivers were asked about URI signs and symptoms at the time of OCD onset, PANDAS symptoms, OCD and tic symptoms, comorbidity, and putative PANDAS risk factors. Specific inquiry regarding URI symptoms proved more informative than general inquiry. In the URI present versus URI absent group, more patients experienced a sudden rather than insidious onset of symptoms. Additionally, more patients with a URI plus sudden onset exhibited a comorbid tic disorder. Until validated biomarkers permit retrospective diagnosis, a history that OCD began around the time of a URI should clue the clinician to look prospectively for PANDAS. Additional research is required to define the boundaries of PANDAS and to develop psychometrically reliable and valid diagnostic strategies.     

Tic disorders and obsessive-compulsive disorder: Is autoimmunity involved?

The precise cause of tic disorders and paediatric obsessive-compulsive disorder (OCD) is unknown. In addition to genetic factors, autoimmunity may play a role, possibly as a sequela of preceding streptococcal throat infections in susceptible children. Here we review the most recent findings, from July 2003 onwards, with regard to a possible relationship between tics/OCD and autoimmunity. Evidence about an intriguing correlation between streptococcal infections and tic disorders and OCD is accumulating. Specific criteria have been outlined for paediatric autoimmune disorders associated with streptococcal infections (PANDAS), but autoimmunity may also be involved in tic disorders and/or OCD in general. Anti-basal ganglia auto-antibodies are an important potential indicator of autoimmunity. Although the lack of a standardized methodology makes comparisons of findings difficult, new data has emerged pointing to the possible involvement of specific auto-antigens. Earlier findings of increased D8/17 B cell expression as a putative susceptibility marker could not be replicated, possibly due to instability of the D8/17-binding antibody. Although PANDAS patients have been reported to improve after therapeutic plasma exchange, and antibiotics may prevent symptom exacerbations, immune-based treatments should not be routinely given. In future studies, demonstrating the pathogenetic significance of anti-basal ganglia antibodies in animals is a major challenge to draw any firm conclusions about a role for autoimmunity. Future longitudinal studies should be aimed at assessing the precise relationship between symptom exacerbations, infections, and immune parameters, possibly along with gene expression profiles.     

Tic disorders and obsessive-compulsive disorder: is autoimmunity involved?

The precise cause of tic disorders and paediatric obsessive-compulsive disorder (OCD) is unknown. In addition to genetic factors, autoimmunity may play a role, possibly as a sequela of preceding streptococcal throat infections in susceptible children. Here we review the most recent findings, from July 2003 onwards, with regard to a possible relationship between tics/OCD and autoimmunity. Evidence about an intriguing correlation between streptococcal infections and tic disorders and OCD is accumulating. Specific criteria have been outlined for paediatric autoimmune disorders associated with streptococcal infections (PANDAS), but autoimmunity may also be involved in tic disorders and/or OCD in general. Anti-basal ganglia auto-antibodies are an important potential indicator of autoimmunity. Although the lack of a standardized methodology makes comparisons of findings difficult, new data has emerged pointing to the possible involvement of specific auto-antigens. Earlier findings of increased D8/17 B cell expression as a putative susceptibility marker could not be replicated, possibly due to instability of the D8/17-binding antibody. Although PANDAS patients have been reported to improve after therapeutic plasma exchange, and antibiotics may prevent symptom exacerbations, immune-based treatments should not be routinely given. In future studies, demonstrating the pathogenetic significance of anti-basal ganglia antibodies in animals is a major challenge to draw any firm conclusions about a role for autoimmunity. Future longitudinal studies should be aimed at assessing the precise relationship between symptom exacerbations, infections, and immune parameters, possibly along with gene expression profiles.     

Psychiatric disorders in first-degree relatives of children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS)

OBJECTIVE: To determine the rates of psychiatric disorders in the first-degree relatives of children with infection-triggered obsessive-compulsive disorder (OCD) and/or tics (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections; PANDAS). METHOD: The probands of this study were 54 children with PANDAS (n = 24 with a primary diagnosis of OCD; n = 30 with a primary diagnosis of a tic disorder). One hundred fifty-seven first-degree relatives (100 parents [93%] and 57 siblings [100%]) were evaluated for the presence of a tic disorder. One hundred thirty-nine first-degree relatives (100 parents [93%] and 39 of 41 siblings over the age of 6 [95%]) were evaluated with clinical and structured psychiatric interviews to determine the presence of subclinical OCD, OCD, and other DSM-IV Axis I disorders. RESULTS: Twenty-one probands (39%) had at least one first-degree relative with a history of a motor or vocal tic; 6 mothers (11%), 9 fathers (19%), and 8 siblings (16%) received this diagnosis. Fourteen probands (26%) had at least one first-degree relative with OCD; 10 mothers (19%), 5 fathers (11%), and 2 siblings (5%), received this diagnosis. An additional 8 parents (8%) and 3 siblings (8%) met criteria for subclinical OCD. Eleven parents (11%) had obsessive-compulsive personality disorder. CONCLUSIONS: The rates of tic disorders and OCD in first-degree relatives of pediatric probands with PANDAS are higher than those reported in the general population and are similar to those reported previously for tic disorders and OCD. Further study is warranted to determine the nature of the relationship between genetic and environmental factors in PANDAS.     

Obsessive compulsive disorder: is there an association with childhood streptococcal infections and altered immune function?

During the last few years, an increased interest in the possibility of immune mediated pathophysiology of obsessive compulsive disorder (OCD) and related disorders has been seen. In the late 1980s, the National Institute of Mental Health reported an increase of obsessive compulsive symptoms in patients with Sydenham chorea (SC). Subsequently, a precipitating streptococcal infection in children with sudden onset of OCD symptoms but no chorea led to the coining of PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcus).This association has furthered interest in studying immune parameters in non-PANDAS OCD as well. This article will review the neuropsychiatric findings in OCD and Tourette syndrome (TS) with emphasis placed on PANDAS, and its association with SC, and a review of the existing studies that have assessed immunologic measures in patients with OCD and TS.     

The question of PANDAS in adults.

BACKGROUND: Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) are a well-defined cause of obsessive-compulsive disorder in children. However, they have not been described or fully investigated in adults newly diagnosed with obsessive-compulsive disorder. METHODS: We describe an adult with onset of obsessive-compulsive disorder at 25 years of age after a severe antibiotic-responsive pharyngitis. He was evaluated with multiple psychiatric rating scales for obsessive-compulsive disorder and Tourette's syndrome, as well as with serologic assays and radiologic studies. RESULTS: In all respects except age our patient fulfilled established criteria for PANDAS. Assays for antibodies to group A beta-hematolytic streptococci, serum D8,17 lymphocytes, antistriatal (neuronal) antibodies, and anticytoskeletal antibodies all supported the hypothesis that a poststreptococcal process was active. Magnetic resonance imaging was abnormal and is described. CONCLUSIONS: The findings suggest that this patient's illness is similar to PANDAS in presentation and that poststreptococcal disease may result in adult-onset obsessive-compulsive disorder.     

Is Tourette's syndrome an autoimmune disease?

We provide a review of recent research findings which support the involvement of autoimmunity in childhood-onset tic disorders, in particular the presence of antineuronal autoantibodies, D8/17 B lymphocyte overexpression, a marker of chorea associated with streptococcal infection, and possible beneficial effects of immunomodulatory intervention. One of the most controversial areas in this field is the validity of the proposed PANDAS concept. Some researchers have delineated a putatively unique subgroup of patients, from the spectrum of illness encompassing Tourette's syndrome and obsessive-compulsive disorder (OCD), whose tics and obsessive-compulsive symptoms are shown to arise in response to beta-hemolytic streptococcal infections. They designated it by the term pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Herein we additionally present pros and cons concerning the concept of PANDAS. Finally, recommendations for future research directions are given.     

Antineuronal antibodies in a group of children with obsessive-compulsive disorder and Tourette syndrome

An autoimmune hypothesis has been suggested for early onset obsessive-compulsive disorder and Tourette syndrome. The term: Paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) has been proposed as an aetiological subtype of OCD and TS, related to a Group A beta haemolytic streptococcal (GABHS) infection that triggers an autoimmune response. Antineural antibodies have been studied and found in the sera of some patients with these disorders, and they are thought to cross-react with streptococcal and basal ganglia antigens. The present study included 32 prepubertal-onset OCD patients, 21 with TS diagnosis (some of them meeting criteria for PANDAS) and 19 normal children, all aged between 9 and 17 years. Antibodies were assayed by immunohistochemistry and immunoblot. Special attention was paid to the methodology and a high serum dilution was used to minimize non-specific binding. No anti-basal ganglia antibodies were detected by immunohistochemistry in any of the samples. Two proteins, with approximate molecular weights of 86 kDa and 55 kDa, were found in sera from 7 patients. Though the study supports the hypothesis of an autoimmune process underlying OCD or TS in some patients, further research is needed.     

Autoimmune neurological disorders associated with group-A beta-hemolytic streptococcal infection

Although central nervous system (CNS) disorders associated with group-A beta-hemolytic streptococcal (GABHS) infection occur only rarely, Sydenham’s chorea is a well-recognized disease that can arise following infection. Children may develop a tic, obsessive compulsive disorder (OCD), and extrapyramidal movement subsequent to GABHS infection. These disorders have been termed pediatric autoimmune neuropsychiatric disorders associated with streptococci (PANDAS). Herein we report one case each of acute disseminated encephalomyelitis (ADEM), PANDAS and subacute encephalitis associated with GABHS infection. To evaluate the pathogenesis of the CNS disorders associated with GABHS infection, we measured levels of neurotransmitters, cytokines, anti-neuronal autoantibodies, and performed immunohistochemistry using patient sera to stain human brain sections. All three cases showed psychiatric behavioral disorders. Immunotherapy was effective, and homovanillic acid levels in the cerebrospinal fluid (CSF) were elevated at the acute stage in all three cases. In each case of ADEM and PANDAS, immunohistochemistry demonstrated neuronal impairment in the basal ganglia during the acute stage. Neuronal immunoreactivity was visualized in the cerebral cortex at the acute stage in the case of subacute encephalitis. There was no direct correlation between immunoreactivity of patient sera on the brain sections and positivity of anti-neuronal autoantibodies or CSF biomarkers. The results suggest that autoimmune responses may modulate neurotransmission, and the use of patient serum for immunohistochemistry is a sensitive screening method for the detection of anti-neuronal autoantibodies in CNS disorders associated with GABHS infection.     

Mycoplasma pneumoniae infection and obsessive-compulsive disease: a case report

It has been demonstrated that obsessive-compulsive disease and/or tic syndromes in children may be triggered by an antecedent infection especially with group A beta-hemolytic streptococci, and this subgroup of children has been designated by the acronym PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections). Other infectious agents such as viruses and bacteria have also been reported to be associated with the acute onset or dramatic exacerbation of obsessive-compulsive disease or Tourette syndrome, and another acronym, PITAND (pediatric infection-triggered autoimmune neuropsychiatric disorder) has appeared in the literature. The involvement of other infectious agents such as Mycoplasma pneumoniae has been described in single case reports. We describe a case of a 5.5-year-old boy who suddenly developed obsessive-compulsive disease symptoms during a M. pneumoniae pneumonia. After treatment with oral clarithromycin, all his obsessive-compulsive disease symptoms disappeared. To our knowledge, this is the first report that shows the association between Mycoplasma pneumoniae infection and obsessive-compulsive disease.     

Obsessive-compulsive disorder and immunology: a review

Interest in the possibility of an immune-mediated pathophysiology of obsessive-compulsive disorder and related disorders has increased. In the late 1980s, the National Institute of Mental Health reported an increase in obsessive-compulsive symptoms (OCS) in patients with Sydenham chorea (SC). Subsequently, a precipitating streptococcal infection in children with sudden onset of OCS but no chorea led to the coining of PANDAS (Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection). This association has furthered interest in biological measures for immune and genetic susceptibility in non-PANDAS obsessive-compulsive disorder patients (OCD). Furthermore, some studies are trying to demonstrate alterations of immune parameters in OCD patients, with few positive results. In this narrative review, our objective was to describe the immunologic findings in OCD, PANDAS, and their association with SC.     

Detecting pediatric autoimmune neuropsychiatric disorders associated with streptococcus in children with obsessive-compulsive disorder and tics.

BACKGROUND: A subgroup of children with obsessive-compulsive and tic disorders are proposed to have an infectious trigger. The purpose of this study was to investigate the relationship between group A streptococcal titers and symptom fluctuations in children with a clinical course resembling that described for pediatric autoimmune neuropsychiatric disorders associated with streptococcus. METHODS: Twenty-five children with obsessive-compulsive disorder and/or tic disorder were evaluated for neuropsychiatric severity and group A streptococcal antibody titers (streptolysin O, deoxyribonuclease B, and carbohydrate A) at 6-week intervals for > or = six consecutive evaluations (total visits=277). RESULTS: Children with large symptom fluctuations (n=15) were compared with children without dramatic fluctuations (n=10). Co-movements of obsessive-compulsive/tic severity and group A streptococcal antibodies were assessed. In subjects with large symptom changes, positive correlations were found between streptococcal titers and obsessive-compulsive severity rating changes (p=.0130). These subjects were also more likely to have elevated group A streptococcal titers during the majority of observations (p=.001). Tic symptom exacerbations occurred more often in the fall/winter months than spring/summer months (p=.03). CONCLUSIONS: Patients with marked obsessive-compulsive/tic symptom changes may be characterized by streptococcal titer elevations and exhibit evidence of seasonal tic exacerbations.     

Increased serum levels of interleukin-12 and tumor necrosis factor-alpha in Tourette's syndrome.

BACKGROUND: The hypothesis that common infections can modulate the onset and course of tic disorders and early-onset obsessive-compulsive disorder (OCD) in pediatric populations is longstanding. To date, most investigations have focused on the hypothesis of molecular mimicry and humoral immune responses. This study was carried out to investigate whether cytokines associated with the innate immune response or T cell activation were altered under baseline conditions and during periods of symptom exacerbation. METHODS: Forty-six patients with Tourette's syndrome and/or early-onset OCD, aged 7-17 years, and 31 age-matched control subjects participated in a prospective longitudinal study. Ratings of clinical severity and serum were collected at regular intervals, and serum concentrations of 10 cytokines were measured repeatedly. RESULTS: Interleukin-12 and tumor necrosis factor alpha concentrations at baseline were elevated in patients compared with control subjects. Both of these markers were further increased during periods of symptom exacerbation. CONCLUSIONS: These findings suggest that symptom exacerbations are associated with an inflammatory process propagated by systemic and local cytokine synthesis that might involve the central nervous system. We conclude that, in the future, longitudinal studies of children with neuropsychiatric disorders should examine the involvement of innate and T cell immunity.     

Diversity of obsessive-compulsive disorder and pharmacotherapy associated with obsessive-compulsive spectrum disorders

Serotonin reuptake inhibitors (SRI) are effective in the treatment of obsessive-compulsive disorder (OCD). The response rate for SRI is approximately 50% and refractory OCD may exist. The effect of antipsychotics augmentation therapy has been established for this kind of patients. However, OCD is clinically and biologically heterogeneous neuropsychiatric disease and it will affect the response of pharmacotherapy. Several subtypes of OCD have been identified. Early onset OCD and hoarding symptoms dominant patients with OCD tend to resist SRI treatment. Antipsychotics augmentation with SRI is much effective for OCD with tic disorders. On the other hand, psychiatric disorders in obsessive-compulsive spectrum disorders (OCSD) have similar clinical symptoms, comorbidities, genetic factors, and neurobiological etiology. SRI is effective for patients with body dysmorphic disorder (BDD) in preoccupation with body appearance or sensation subgroup. The response of SRI in BDD is similar to OCD while that of eating disorders was different. Impulse control disorders will respond to opiate antagonist but not to SRI. This subgroup might have a characteristic of behavioral addiction. Antipsychotic agents are effective for neurological disorders including tic disorders, Tourette syndrome, and autistic spectrum disorders. Therefore, the dopaminergic pathophysiology might underlie in this subgroup. The main goal of DSM-V is to make diagnosis based on biological validity, and the treatment response is an important factor. Further studies are necessary for understanding the pathophysiology of OCSD.     

Infection-triggered anorexia nervosa in children: clinical description of four cases

BACKGROUND: Anorexia nervosa (AN) is a serious illness with no definitive treatment. Clinical and research evidence led to the hypothesis that some children with AN may have a pediatric autoimmune neuropsychiatric disorder associated with streptococcus (PANDAS), similar in pathogenesis to other hypothesized PANDAS disorders. METHODS: Four youngsters (ages, 11-15 years) with PANDAS AN were treated with an open trial of antibiotics, in addition to conventional treatment. They were evaluated for eating disorder and obsessive-compulsive symptoms, and for weight gain. Evidence of streptococcal infection came from clinical evaluation, throat cultures, and two serological tests: anti-deoxyribonuclease B (anti-DNase B) and anti-streptolysin O (ASO) titers. The "rheumatic" marker D8/17 was also measured. This B-cell alloantigen is associated, in several publications, with poststreptococcal autoimmunity: Rheumatic fever (RF), Sydenham's chorea (SC), and possibly PANDAS obsessive compulsive disorder (OCD) and tic disorders. RESULTS: There was clinical evidence of possible antecedent streptococcal infection in all four patients, two of whom had comorbid OCD, with possible infection-triggered AN. All four had the rheumatic marker: A percentage of D8/17-positive B cells of 28-38%, with a mean of 33% (12% or more is considered positive for the marker). The patients responded to conventional treatment plus antibiotics with weight restoration and decreased eating disorder and obsessive-compulsive symptoms. Three needed to gain weight and did so. CONCLUSIONS: There may be a link between infectious disease and some cases of AN, which raises the possibility of new treatment.