Cognition and gut microbiota in schizophrenia spectrum and mood disorders: A systematic review.

FRILEUX, M., BOLTRI M. and al. Cognition and Gut microbiota in schizophrenia spectrum and mood disorders: a Systematic Review. NEUROSCI BIOBEHAV REV (1) 2024 Schizophrenia spectrum disorders and major mood disorders are associated with cognitive impairments. Recent studies suggest a link between gut microbiota composition and cognitive functioning. Here, we review the relationship between gut microbiota and cognition in these disorders. To do this, we conducted a systematic review, searching Cochrane Central Register of Controlled Trials, EBSCOhost, Embase, Pubmed, Scopus, and Web of Science. Studies were included if they investigated the relationship between gut microbiota composition and cognitive function through neuropsychological assessments in patients with bipolar, depressive, schizophrenia spectrum, and other psychotic disorders. Ten studies were identified. Findings underscore a link between gut dysbiosis and cognitive impairment. This relationship identified specific taxa (Haemophilus, Bacteroides, and Alistipes) as potential contributors to bolstered cognitive performance. Conversely, Candida albicans, Toxoplasma gondii, Streptococcus and Deinococcus were associated with diminished performance on cognitive assessments. Prebiotics and probiotics interventions were associated with cognitive enhancements, particularly executive functions. These results emphasize the role of gut microbiota in cognition, prompting further exploration of the underlying mechanisms paving the way toward precision psychiatry.

Infant microbes and metabolites point to childhood neurodevelopmental disorders.

This study has followed a birth cohort for over 20 years to find factors associated with neurodevelopmental disorder (ND) diagnosis. Detailed, early-life longitudinal questionnaires captured infection and antibiotic events, stress, prenatal factors, family history, and more. Biomarkers including cord serum metabolome and lipidome, human leukocyte antigen (HLA) genotype, infant microbiota, and stool metabolome were assessed. Among the 16,440 Swedish children followed across time, 1,197 developed an ND. Significant associations emerged for future ND diagnosis in general and for specific ND subtypes, spanning intellectual disability, speech disorder, attention-deficit/hyperactivity disorder, and autism. This investigation revealed microbiome connections to future diagnosis as well as early emerging mood and gastrointestinal problems. The findings suggest links to immunodysregulation and metabolism, compounded by stress, early-life infection, and antibiotics. The convergence of infant biomarkers and risk factors in this prospective, longitudinal study on a large-scale population establishes a foundation for early-life prediction and intervention in neurodevelopment.

Microbiota and Metabolite Profiling as Markers of Mood Disorders: A Cross-Sectional Study in Obese Patients.

Obesity is associated with an increased risk of several neurological and psychiatric diseases, but few studies report the contribution of biological features in the occurrence of mood disorders in obese patients. The aim of the study is to evaluate the potential links between serum metabolomics and gut microbiome, and mood disturbances in a cohort of obese patients. Psychological, biological characteristics and nutritional habits were evaluated in 94 obese subjects from the Food4Gut study stratified according to their mood score assessed by the Positive and Negative Affect Schedule (PANAS). The fecal gut microbiota and plasma non-targeted metabolomics were analysed. Obese subjects with increased negative mood display elevated levels of Coprococcus as well as decreased levels of Sutterella and Lactobacillus. Serum metabolite profile analysis reveals in these subjects altered levels of several amino acid-derived metabolites, such as an increased level of L-histidine and a decreased in phenylacetylglutamine, linked to altered gut microbiota composition and function rather than to differences in dietary amino acid intake. Regarding clinical profile, we did not observe any differences between both groups. Our results reveal new microbiota-derived metabolites that characterize the alterations of mood in obese subjects, thereby allowing to propose new targets to tackle mood disturbances in this context. Food4gut, clinicaltrial.gov: NCT03852069.

Targeting the microbiome-gut-brain axis for improving cognition in schizophrenia and major mood disorders: A narrative review.

Cognitive impairment has been consistently found to be a core feature of serious mental illnesses such as schizophrenia and major mood disorders (major depression and bipolar disorder). In recent years, a great effort has been made in elucidating the biological causes of cognitive deficits and the search for new biomarkers of cognition. Microbiome and gut-brain axis (MGB) hormones have been postulated to be potential biomarkers of cognition in serious mental illnesses. The main aim of this review was to synthesize current evidence on the association of microbiome and gut-brain hormones on cognitive processes in schizophrenia and major mood disorders and the association of MGB hormones with stress and the immune system. Our review underscores the role of the MGB axis on cognitive aspects of serious mental illnesses with the potential use of agents targeting the gut microbiota as cognitive enhancers. However, the current evidence for clinical trials focused on the MGB axis as cognitive enhancers in these clinical populations is scarce. Future clinical trials using probiotics, prebiotics, antibiotics, or faecal microbiota transplantation need to consider potential mechanistic pathways such as the HPA axis, the immune system, or gut-brain axis hormones involved in appetite control and energy homeostasis.

The endocannabinoidome as a substrate for noneuphoric phytocannabinoid action and gut microbiome dysfunction in neuropsychiatric disorders
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The endocannabinoid (eCB) system encompasses the eCBs anandamide and 2-arachidonoylglycerol, their anabolic/catabolic enzymes, and the cannabinoid CB1 and CB2 receptors. Its expansion to include several eCB-like lipid mediators, their metabolic enzymes, and their molecular targets, forms the endocannabinoidome (eCBome). This complex signaling system is deeply involved in the onset, progress, and symptoms of major neuropsychiatric disorders and provides a substrate for future therapeutic drugs against these diseases. Such drugs may include not only THC, the major psychotropic component of cannabis, but also other, noneuphoric plant cannabinoids. These compounds, unlike THC, possess a wide therapeutic window, possibly due to their capability of hitting several eCBome and non-eCBome receptors. This is particularly true for cannabidiol, which is one of the most studied cannabinoids and shows promise for the treatment of a wide range of mental and mood disorders. The eCBome plays a role also in the microbiota-gut-brain axis, which is emerging as an important actor in the control of affective and cognitive functions and in their pathological alterations.
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El sistema endocannabinoide (SeCB) incluía los eCB anandamida y 2-araquidonoilglicerol, sus enzimas anabólicas / catabólicas y los receptores cannabinoides CB1 y CB2. Su expansión para incluir algunos mediadores lipídicos similares al SeCB, sus enzimas metabólicas y sus dianas moleculares (Fig. 1), forma el endocannabinoidoma (eCBoma). Este complejo sistema de señalización está profundamente involucrado en la aparición, la progresión y los síntomas de los principales trastornos neuropsiquiátricos y proporciona un sustrato para futuros fármacos terapéuticos contra estas enfermedades. Tales drogas pueden incluir no solo THC, el principal componente psicotrópico de la cannabis, sino también otros cannabinoides vegetales no euforizantes. Estos compuestos, a diferencia del THC, poseen una amplia ventana terapéutica, posiblemente debido a su capacidad de actuar sobre varios receptores eCBoma y no eCBoma. Esto es particularmente cierto para el cannabidiol, que es uno de los cannabinoides más estudiados y que aparece prometedor para el tratamiento de una amplia gama de trastornos mentales y del estado de ánimo. El eCBoma también tiene un papel en el eje microbiota-intestino-cerebro, que se perfila como un actor importante en el control de las funciones afectivas y cognitivas y en sus alteraciones patológicas.

Le système endocannabinoïde (eCB) comprend les récepteurs cannabinoïdes CB1 et CB2 et les endocannabinoϊdes endogènes l'anandamide et le 2-arachidonoylglycérol ainsi que leurs enzymes anaboliques/cataboliques. L'endocannabinoϊdome (eCBome) est formé de ce système eCB et de plusieurs médiateurs lipidiques de type eCB, leurs enzymes métaboliques et leurs cibles moléculaires (Fig. 1). Ce système de signalisation complexe est profondément impliqué dans l'apparition, la progression et les symptômes des principaux troubles neuropsychiatriques et offre une base pour le développement de futurs traitements contre ces maladies. Ces médicaments peuvent contenir du THC, le principal composant psychotrope du cannabis, et aussi d'autres cannabinoïdes végétaux non euphorisants dont la fenêtre thérapeutique est large, contrairement au THC, peut-être en raison de leur capacité à atteindre plusieurs récepteurs eCBome et non eCBome. C'est particulièrement vrai pour le cannabidiol, l'un des cannabinoïdes les plus étudiés qui s'avère prometteur pour traiter un large spectre de troubles mentaux et de l'humeur. L'eCBome joue également un rôle dans l'axe microbiote-intestin-cerveau, acteur important dans le contrôle des fonctions affectives et cognitives et des pathologies qui y sont liées.

Evaluation of the Prebiotic Potential of a Commercial Synbiotic Food Ingredient on Gut Microbiota in an Ex Vivo Model of the Human Colon.

Behavior and mood disorders have been linked to gut microbiota dysbiosis through the "microbiota-gut-brain axis". Microbiota-targeting interventions are promising therapeutic modalities to restore or even maintain normal microbiome composition and activity in these disorders. Here, we test the impact of a commercial synbiotic formulation on gut microbiota composition and metabolic activity. We employed an ex-vivo continuous fermentation model that simulates the proximal colon to assess the effect of this formulation on microbiota structure and functionality as compared to no treatment control and microcrystalline cellulose as a dietary fiber control. The test formulation did not alter the diversity of gut microbiota over 48 h of treatment. However, it induced the enrichment of Lactobacillus, Collinsella and Erysipelotrichaceae. The test formulation significantly increased the level of microbiota-generated butyrate within 12 h of treatment as compared to 24 h required by microcrystalline cellulose to boost its production. The test formulation did not lead to a significant change in amino acid profiles. These results provide evidence of potential benefits related to synbiotic effects and general gut health and support the potential of this food formulation as a therapeutic dietary intervention in mood and behavior disorders.

From Probiotics to Psychobiotics: Live Beneficial Bacteria Which Act on the Brain-Gut Axis.

There is an important relationship between probiotics, psychobiotics and cognitive and behavioral processes, which include neurological, metabolic, hormonal and immunological signaling pathways; the alteration in these systems may cause alterations in behavior (mood) and cognitive level (learning and memory). Psychobiotics have been considered key elements in affective disorders and the immune system, in addition to their effect encompassing the regulation of neuroimmune regulation and control axes (the hypothalamic-pituitary-adrenal axis or HPA, the sympathetic-adrenal-medullary axis or SAM and the inflammatory reflex) in diseases of the nervous system. The aim of this review is to summarize the recent findings about psychobiotics, the brain-gut axis and the immune system. The review focuses on a very new and interesting field that relates the microbiota of the intestine with diseases of the nervous system and its possible treatment, in neuroimmunomodulation area. Indeed, although probiotic bacteria will be concentrated after ingestion, mainly in the intestinal epithelium (where they provide the host with essential nutrients and modulation of the immune system), they may also produce neuroactive substances which act on the brain-gut axis.

From isoniazid to psychobiotics: the gut microbiome as a new antidepressant target.

An awareness of the importance of the gut-brain axis in psychiatric disorders such as depression is increasing. The gut microbiome is a key component of this axis. Gut bacteria can communicate with the brain through a variety of pathways including the hypothalamic-pituitary-adrenal axis, immune modulation, tryptophan metabolism and the production of various neuroactive compounds. Patients with depression, and other mood and anxiety disorders, show distinct compositional changes in their gut bacteria profile, raising the question about a possible aetiological role for the microbiome in these disorders. Evidence is emerging that the gut microbiome may represent a new potential antidepressant target and the term 'psychobiotic' has been coined to describe bacteria which confer mental health benefits. Gut bacteria are easily accessible and can be altered in a variety of ways including through the use of probiotics, prebiotics and dietary change. Psychobiotics containing various Lactobacillus and Bifidobacterium species have demonstrated the ability to improve mood, reduce anxiety and enhance cognitive function in both healthy populations and patient groups. This article provides an overview of the identification and development of antidepressant psychobiotics, from the preclinical evidence in the laboratory to the more recent encouraging results from human trials.

The Relationship Between Perinatal Mental Health and Stress: a Review of the Microbiome.

PURPOSE OF REVIEW: Our current understanding of the underlying mechanisms and etiologies of perinatal mood and anxiety disorders (PMADs) is not clearly identified. The relationship of stress-induced adaptations (i.e., the hypothalamic-pituitary-adrenal (HPA) axis, the autonomic nervous system (ANS), the immune system) and the microbiota are potential contributors to psychopathology exhibited in women during pregnancy and postpartum and should be investigated. RECENT FINDINGS: The stress response activates the HPA axis and dysregulates the ANS, leading to the inhibition of the parasympathetic system. Sustained high levels of cortisol, reduced heart variability, and modulated immune responses increase the vulnerability to PMAD. Bidirectional communication between the nervous system and the microbiota is an important factor to alter host homeostasis and development of PMAD. Future research in the relationship between the psychoneuroimmune system, the gut microbiota, and PMAD has the potential to be integrated in clinical practice to improve screening, diagnosis, and treatment.

Emerging literature in the Microbiota-Brain Axis and Perinatal Mood and Anxiety Disorders.

Perinatal Mood and Anxiety Disorders (PMAD) are common and can cause significant morbidity and mortality for mother and child. A healthy perinatal period requires significant adaptations; however, systems can become imbalanced resulting in depressive and anxiety symptoms. The interface between the microbiome, the immune system, and the stress system may be a model for understanding mechanisms underlying PMAD. Emerging literature from general populations regarding immune, hormone, and HPA axis changes in relation to the microbiome combined with literature on immune, gonadotropin, and stress systems in the perinatal period provides a background. We systematically investigated literature in the developing field of the microbiome in relation to PMAD. Our inclusion criteria were 1) reporting measure of maternal mood, stress, or anxious or depressed behavior; 2) in the perinatal period, defined as pregnancy through one year postpartum; and 3) reporting measure of maternal microbiome including manipulations of the microbiome through prebiotics, probiotics, or interventions with microbial byproducts. The review identified research studying associations between stress and maternal microbiome; dietary impacts on microbial composition, mood, and stress; and the relationship between the microbiome and the immune system through immunoregulatory mechanisms. Important themes identified include: the importance of studying the maternal microbiome and measures of stress, anxiety, and depression and that multi-hit models will be needed as research strives to determine the effects of multiple mechanisms working in concert.

Differences in the association between persistent pathogens and mood disorders among young- to middle-aged women and men in the U.S.

BACKGROUND: A growing literature supports the role of immune system alterations in the etiology of mood regulation, yet there is little population-based evidence regarding the association between persistent pathogens, inflammation and mood disorders among younger women and men in the U.S. METHODS: We used data from the National Health and Nutrition Examination Survey III on individuals 15-39 years of age assessed for major depression, dysthymia, and/or bipolar disorder I and tested for cytomegalovirus (N=6825), herpes simplex virus (HSV)-1 (N=5618) and/or Helicobacter pylori (H. pylori) (N=3167) seropositivity as well as C-reactive protein (CRP) level (N=6788). CMV immunoglobulin G (IgG) antibody level was also available for a subset of women (N=3358). We utilized logistic regression to estimate the odds ratio (OR) and 95% confidence interval (CI) for the association between pathogens, CRP levels and each mood disorder overall and among women and men, separately. RESULTS: H. pylori seropositivity was associated with increased odds of dysthymia (OR 2.37, 95% confidence interval (CI): 1.07, 5.24) among women, but decreased odds among men (OR 0.51, 95% CI: 0.28, 0.92). CMV seropositivity was also associated with lower odds of depression (OR 0.54, 95% CI: 0.32, 0.91) among men, while elevated CMV IgG level was marginally associated with increased odds of mood disorders among women. Associations were not mediated by CRP level. CONCLUSIONS: Our findings suggest that persistent pathogens such as CMV and H. pylori may differentially influence mood disorders among women and men, warranting further investigation into biological and/or sociocultural explanations for the contrasting associations observed.

Estimation of cognitive and affective disorders occurrence in patients with Lyme borreliosis.

INTRODUCTION AND OBJECTIVE: Lyme borreliosis (LB) is a disease caused by the bacteria Borrelia burgdorferi. The most common symptoms are related to the skin, musculo-scelatal system, central and peripheral nervous system, rarely to the heart muscle and the eye, and may occur in the multistage course of the disease. LB may additionally be accompanied by psychopathological symptoms. The aim of the study is estimation of the cognitive and affective disorders occurence in patients with LB. MATERIAL AND METHODS: The study was carried out in the group of 121 patients (61 females, 60 males) aged 18-65; mean age 46 years. All patients were diagnosed with late-stage of LB: 46 patients (38%) with Lyme arthritis and 75 patients (62%) with neuroborreliosis. Evaluation of the cognitive and affective functioning of patients was performed on the basis of a standardized interview and test methods: the Mini-Mental State Examination (MMSE), Clock Drawing Test (CDT) and the Beck Depression Inventory (BDI). RESULTS: Cognitive disorders occurred statistically significantly more often in patients with neuroborreliosis (14.7%) than in patients with Lyme arthritis (4.3%). A group of females with neuroborreliosis and a group of males with the same diagnosis demonstrated cognitive deficits significantly more often (23.3% and 8.9%, respectively), compared to groups of patients with Lyme arthritis (6.5% in females and no cognitive deficits in males). A significantly higher percentage of depressive disorders was also noted in the group of males and females with neuroborreliosis (50.7%), compared to the group of patients with Lyme arthritis (39.1%). The symptoms of depression were particularly frequent in the females with neuroborreliosis (60%). The severity of depression measured by BDI was mild or moderate in most cases. In the examined groups, more patients with neuroborreliosis (44%), both in females (36.7%) and males (48.9%), demonstrated anxiety disorders. The obtained results showed a higher frequency of affective disorders compared to cognitive deficits, both in patients with Lyme arthritis and neuroborreliosis. CONCLUSIONS: An increased frequency of depressive and neurotic disorders was observed in patients with LB, particularly in patients with neuroborreliosis. Neurotic disorders, mainly adaptive, were most common in males with LB, while depressive disorders were more frequent in females. An increased frequency of cognitive deficits was observed in patients with neuroborreliosis, particularly in females.

Gut microbiota in autism and mood disorders.

The hypothesis of an important role of gut microbiota in the maintenance of physiological state into the gastrointestinal (GI) system is supported by several studies that have shown a qualitative and quantitative alteration of the intestinal flora in a number of gastrointestinal and extra-gastrointestinal diseases. In the last few years, the importance of gut microbiota impairment in the etiopathogenesis of pathology such as autism, dementia and mood disorder, has been raised. The evidence of the inflammatory state alteration, highlighted in disorders such as schizophrenia, major depressive disorder and bipolar disorder, strongly recalls the microbiota alteration, highly suggesting an important role of the alteration of GI system also in neuropsychiatric disorders. Up to now, available evidences display that the impairment of gut microbiota plays a key role in the development of autism and mood disorders. The application of therapeutic modulators of gut microbiota to autism and mood disorders has been experienced only in experimental settings to date, with few but promising results. A deeper assessment of the role of gut microbiota in the development of autism spectrum disorder (ASD), as well as the advancement of the therapeutic armamentarium for the modulation of gut microbiota is warranted for a better management of ASD and mood disorders.

The Role of the Microbiome in the Relationship of Asthma and Affective Disorders.

The effect of stress, anxiety and other affective states on inflammatory conditions such as asthma is well documented. Although several immune pathway mechanisms have been proposed and studied, they cannot fully explain the relationship. In this chapter we present a new perspective on asthma development and exacerbation that integrates findings on the role of psychological factors in asthma with the microbiome and the hygiene hypothesis in asthma development.

Dyspeptic symptoms in patients with type 1 diabetes: endoscopic findings, Helicobacter pylori infection, and associations with metabolic control, mood disorders and nutritional factors.

OBJECTIVES: To evaluate, in a group of patients with long-standing type 1 diabetes (DM1), an association of dyspepsia symptoms with: changes in the gastroduodenal mucosa, infection by Helicobacter pylori, glycemic control, and psychological and nutritional factors. SUBJECTS AND METHODS: A total of 32 patient with DM1 were studied (age: 38 ± 9 years; females: 25; diabetes duration: 22 ± 5 years). All patients answered a standardized questionnaire for the evaluation of gastrointestinal symptoms and underwent upper gastrointestinal endoscopy, with gastric biopsies for the evaluation of Helicobacter pylori infection. The presence of anxiety and depression was evaluated by the HAD scale. Nutritional parameters were BMI, arm and waist circumference, skinfold measurement, and body fat percentage. RESULTS: Upper endoscopy detected lesions in the gastric mucosa in 34.4% of the patients, with similar frequency in those with (n = 21) and without dyspepsia (n = 11). The patients with dyspepsia complaints showed greater frequency of depression (60% vs. 0%; p = 0.001), higher values for HbA1c (9.6 ± 1.7 vs. 8.2 ± 1.3%; p = 0.01) and lower values for BMI (24.3 ± 4.1 vs. 27.2 ± 2.6 kg/m2; p = 0.02), body fat percentage (26.6 ± 6.2 vs. 30.8 ± 7.7%; p = 0.04), and waist circumference (78.7 ± 8 vs. 85.8 ± 8.1 cm; p = 0.02). No association was found between the symptoms and the presence of Helicobacter pylori. CONCLUSIONS: Dyspepsia symptoms in patients with long-standing DM1 were associated with glycemic control and depression, and they seem to negatively influence the nutritional status of these patients.

Dyspeptic symptoms in patients with type 1 diabetes: endoscopic findings, Helicobacter pylori infection, and associations with metabolic control, mood disorders and nutritional factors

Objectives To evaluate, in a group of patients with long-standing type 1 diabetes (DM1), an association of dyspepsia symptoms with: changes in the gastroduodenal mucosa, infection by Helicobacter pylori, glycemic control, and psychological and nutritional factors. Subjects and methods A total of 32 patient with DM1 were studied (age: 38 ± 9 years; females: 25; diabetes duration: 22 ± 5 years). All patients answered a standardized questionnaire for the evaluation of gastrointestinal symptoms and underwent upper gastrointestinal endoscopy, with gastric biopsies for the evaluation of Helicobacter pylori infection. The presence of anxiety and depression was evaluated by the HAD scale. Nutritional parameters were BMI, arm and waist circumference, skinfold measurement, and body fat percentage. Results Upper endoscopy detected lesions in the gastric mucosa in 34.4% of the patients, with similar frequency in those with (n = 21) and without dyspepsia (n = 11). The patients with dyspepsia complaints showed greater frequency of depression (60% vs. 0%; p = 0.001), higher values for HbA1c (9.6 ± 1.7 vs. 8.2 ± 1.3%; p = 0.01) and lower values for BMI (24.3 ± 4.1 vs. 27.2 ± 2.6 kg/m2; p = 0.02), body fat percentage (26.6 ± 6.2 vs. 30.8 ± 7.7%; p = 0.04), and waist circumference (78.7 ± 8 vs. 85.8 ± 8.1 cm; p = 0.02). No association was found between the symptoms and the presence of Helicobacter pylori. Conclusions Dyspepsia symptoms in patients with long-standing DM1 were associated with glycemic control and depression, and they seem to negatively influence the nutritional status of these patients. .

The gastrointestinal tract microbiome, probiotics, and mood.

Mental health is closely linked to physical health. Depression (e.g., major depression) is highly prevalent worldwide and a major cause of disability. In a subgroup with treatment-resistant depression, standard pharmacotherapy interventions provide small if any incremental improvement in patient outcomes and may also require the application of an alternate approach. Therefore, in addition to the standard pharmacotherapies prescribed, patients will also be advised on the benefits of psychological counseling, electroconvulsive therapy, and transcranial magnetic stimulation or increasing physical activity and reducing harmful substance consumption. Numerous nutraceuticals have a beneficial role in treatment-resistant depression and include, herbal medicines of which Hypericum perforatum is the best studied, omega-3 fatty acid preparations, S-Adenosyl-L-Methionine (SAMe), various mineral formulations (e.g., magnesium) and folate (singly or in combination with B group vitamins) are prescribed to a lesser extent. Furthermore, a largely neglected area of research activity has been the role of live probiotic cultures that contribute to repairing dysbiosis (a leaky gut barrier abnormality) in the gastrointestinal tract (GIT). In this commentary, we build a hypothesis that in addition suggests that GIT metabolites that are elaborated by the microbiome cohort may provide novel and significant avenues for efficacious therapeutic interventions for mood disorders. We posit that the microbiome in the gastrointestinal tract is implicit as an important participant for the amelioration of adverse mood conditions via the diverse metabolic activities provided by live beneficial bacteria (probiotics) as an active adjuvant treatment. This activity is in part triggered by a controlled release of reactive oxygen species (ROS) and hence further questions the antioxidant/oxidative stress postulate.

Dyskinesias and associated psychiatric disorders following streptococcal infections.

BACKGROUND: The classical extrapyramidal movement disorder following beta haemolytic streptococcus (BHS) infection is Sydenham's chorea (SC). Recently, other post-streptococcal movement disorders have been described, including motor tics and dystonia. Associated emotional and behavioural alteration is characteristic. AIMS: To describe experience of post-streptococcal dyskinesias and associated co-morbid psychiatric features presenting to a tertiary referral centre 1999-2002. METHODS: In all patients, dyskinetic movement disorders followed BHS pharyngeal infection. BHS infection was defined by pharyngeal culture of the organism, or paired streptococcal serology. Movement disorders were classified according to international criteria, and validated by experienced child neurologists. Psychiatric complications were defined using ICD-10 criteria using a validated psychiatric interview. RESULTS: In the 40 patients, the following dyskinetic movement disorders were present: chorea (n = 20), motor tics (n = 16), dystonia (n = 5), tremor (n = 3), stereotypies (n = 2), opsoclonus (n = 2), and myoclonus (n = 1). Sixty five per cent of the chorea patients were female, whereas 69% of the tic patients were male. ICD-10 psychiatric diagnoses were made in 62.5%. Using the same psychiatric instrument, only 8.9% of UK children would be expected to have an ICD-10 psychiatric diagnosis. Emotional disorders occurred in 47.5%, including obsessive-compulsive disorder (27.5%), generalised anxiety (25%), and depressive episode (17.5%). Additional psychiatric morbidity included conduct disorders (27.5%) and hyperkinetic disorders (15%). Psychiatric, movement, and post-streptococcal autoimmune disorders were commonly observed in family members. At a mean follow up of 2.7 years, 72.5% had continuing movement and psychiatric disorders. CONCLUSION: Post-streptococcal dyskinesias occur with significant and disabling psychiatric co-morbidity and are potential autoimmune models of common "idiopathic" movement and psychiatric disorders in children. Multiple factors may be involved in disease expression including genetic predisposition, developmental status, and the patient's sex.