1
|
Gao Y, Li H, Luo H, Ni Y, Feng Y, He L, Zhou Q, Hu J, Chen S. Purified Serum IgG from a Patient with Anti-IgLON5 Antibody Cause Long-Term Movement Disorders with Impaired Dopaminergic Pathways in Mice. Biomedicines 2023; 11:2483. [PMID: 37760924 PMCID: PMC10526147 DOI: 10.3390/biomedicines11092483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 08/24/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023] Open
Abstract
Background: Anti-IgLON5 disease is a rare autoimmune disease of the central nervous system. It typically manifests as a chronic condition, characterized by cognitive impairments, movement disorders, and sleep disorders. The mechanisms underlying movement disorders in this disease remain poorly understood due to a lack of research. Furthermore, this disease exhibits both neuroimmune and neurodegenerative characteristics. The objective of this study is to explore the underlying mechanisms of movement disorders caused by anti-IgLON5 antibodies for the first time. Methods: Antibodies were purified from the serum of a confirmed patient of anti-IgLON5 disease. The passive transfer animal models were employed, where antibodies were continuously injected into the substantia nigra pars compacta (SNc) of the mouse midbrain using stereotactic injection to explore the mechanism of movement disorder. The effects of anti-IgLON5 antibodies on dopaminergic neurons in the SNc and neurodegeneration were examined through immunohistochemistry. Changes in neurotransmitter levels in the basal ganglia were assessed using high-performance liquid chromatography. Additionally, RNA-seq was employed to identify the differentially expressed genes associated with the short-term and long-term effects of anti-IgLON5 antibody on the SNc. Results: Mice injected with anti-IgLON5 antibodies in the SNc exhibited persistent movement impairments for up to 3 months. One week after antibody injection, the number of TH neurons significantly decreased compared to the control group, accompanied by reduced projection fibers in the basal ganglia and decreased dopamine levels. After 3 months of antibody injection, an increase in phosphorylated Tau was observed in the SNc of the midbrain. Additionally, long-term sustained activation of microglia was detected in the SNc. The differentially expressed genes of long-term effects of IgLON5 antibodies were different from their short-term effects on the SNc. Conclusion: Purified serum IgG from a patient with anti-IgLON5 antibodies can cause long-term movement disorder in mice. The movement disorders appear to be linked to the impaired dopaminergic pathway, and the increased p-Tau showed neurodegenerative changes induced by the anti-IgLON5 antibody.
Collapse
Affiliation(s)
- Yining Gao
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200023, China; (Y.G.); (H.L.); (Y.N.); (L.H.); (Q.Z.)
| | - Hongxia Li
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200023, China; (Y.G.); (H.L.); (Y.N.); (L.H.); (Q.Z.)
| | - Huoqing Luo
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (H.L.); (Y.F.)
| | - You Ni
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200023, China; (Y.G.); (H.L.); (Y.N.); (L.H.); (Q.Z.)
| | - Yifan Feng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (H.L.); (Y.F.)
| | - Lu He
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200023, China; (Y.G.); (H.L.); (Y.N.); (L.H.); (Q.Z.)
| | - Qinming Zhou
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200023, China; (Y.G.); (H.L.); (Y.N.); (L.H.); (Q.Z.)
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (H.L.); (Y.F.)
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226007, China
| | - Sheng Chen
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200023, China; (Y.G.); (H.L.); (Y.N.); (L.H.); (Q.Z.)
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226007, China
| |
Collapse
|
2
|
Rothenberger A, Heinrich H. Co-Occurrence of Tic Disorders and Attention-Deficit/Hyperactivity Disorder-Does It Reflect a Common Neurobiological Background? Biomedicines 2022; 10:biomedicines10112950. [PMID: 36428518 PMCID: PMC9687745 DOI: 10.3390/biomedicines10112950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/06/2022] [Accepted: 11/09/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The co-existence of tic disorders and attention-deficit/hyperactivity disorder (TD + ADHD) has proven to be highly important in daily clinical practice. The factor ADHD is not only associated with further comorbidities, but also has a long-term negative psychosocial effect, while the factor TD is usually less disturbing for the major part of the patients. It remains unclear how far this is related to a different neurobiological background of the associated disorders or whether TD + ADHD reflects a common one. OBJECTIVE This review provides an update on the neurobiological background of TD + ADHD in order to better understand and treat this clinical problem, while clarifying whether an additive model of TD + ADHD holds true and should be used as a basis for further clinical recommendations. METHOD A comprehensive research of the literature was conducted and analyzed, including existing clinical guidelines for both TD and ADHD. Besides genetical and environmental risk factors, brain structure and functions, neurophysiological processes and neurotransmitter systems were reviewed. RESULTS Only a limited number of empirical studies on the neurobiological background of TD and ADHD have taken the peculiarity of co-existing TD + ADHD into consideration, and even less studies have used a 2 × 2 factorial design in order to disentangle the impact/effects of the factors of TD versus those of ADHD. Nevertheless, the assumption that TD + ADHD can best be seen as an additive model at all levels of investigation was strengthened, although some overlap of more general, disorder non-specific aspects seem to exist. CONCLUSION Beyond stress-related transdiagnostic aspects, separate specific disturbances in certain neuronal circuits may lead to disorder-related symptoms inducing TD + ADHD in an additive way. Hence, within a classificatory categorical framework, the dimensional aspects of multilevel diagnostic-profiling seem to be a helpful precondition for personalized decisions on counselling and disorder-specific treatment in TD + ADHD.
Collapse
Affiliation(s)
- Aribert Rothenberger
- Clinic for Child and Adolescent Psychiatry and Psychotherapy, University Medical Center Göttingen, 37075 Göttingen, Germany
- Correspondence:
| | - Hartmut Heinrich
- Neurocare Group, 80331 Munich, Germany
- Kbo-Heckscher-Klinikum, 81539 Munich, Germany
- Research Institute Brainclinics, Brainclinics Foundation, 6524 AD Nijmegen, The Netherlands
| |
Collapse
|
3
|
Lai M, Li Y, Luo D, Xu J, Li J. Dopamine-2 receptor antibody encephalitis presenting as pure tongue-biting in a tourette syndrome patient: a case report. BMC Psychiatry 2022; 22:47. [PMID: 35057786 PMCID: PMC8772117 DOI: 10.1186/s12888-021-03683-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 12/29/2021] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Tourette syndrome (TS) is a neuropsychiatric disorder characterized by repetitive and patterned tics. Its onset correlates with dysfunctions in immunological activation and neurotransmitters. Autoimmune movement disorders such as dopamine-2 receptor antibody encephalitis (D2R encephalitis) may go undiagnosed in TS patients seeking medical help for tic symptoms only. Here, we present a clinical case of D2R encephalitis in a TS patient. CASE PRESENTATION A 13-year-old boy with a history of TS presented with acute tongue-biting without positive neurologic examination or auxiliary examination results, except for a weakly positive finding for D2R antibodies in the serum sample. He was initially diagnosed with possible D2R encephalitis, but the influence of TS could not be ruled out. In addition to psychotropics, we administered immunotherapy early based on clinical characteristics, and his symptoms were ameliorated significantly. During the follow-up, he was diagnosed with definite D2R encephalitis, and the dosage of psychotropics was further adjusted for fluctuating symptoms. CONCLUSIONS Our case suggests that clinicians should discern D2R encephalitis in TS patients when tics are the primary symptoms. Administering immunotherapy early, according to clinical characteristics, may benefit the patient. Moreover, the features of premonitory urges could help evaluate the state of TS.
Collapse
Affiliation(s)
- Mingfeng Lai
- grid.13291.380000 0001 0807 1581Mental Health Center West China Hospital, Sichuan University, No. 28 Dian Xin Nan Road, Sichuan, Chengdu 610041 China
| | - Yuanyuan Li
- grid.13291.380000 0001 0807 1581Mental Health Center West China Hospital, Sichuan University, No. 28 Dian Xin Nan Road, Sichuan, Chengdu 610041 China
| | - Dan Luo
- grid.13291.380000 0001 0807 1581Mental Health Center West China Hospital, Sichuan University, No. 28 Dian Xin Nan Road, Sichuan, Chengdu 610041 China
| | - Jiajun Xu
- grid.13291.380000 0001 0807 1581Mental Health Center West China Hospital, Sichuan University, No. 28 Dian Xin Nan Road, Sichuan, Chengdu 610041 China
| | - Jing Li
- Mental Health Center West China Hospital, Sichuan University, No. 28 Dian Xin Nan Road, Sichuan, Chengdu 610041, China.
| |
Collapse
|
4
|
Lamothe H, Baleyte JM, Mallet L, Pelissolo A. Trichotillomania is more related to Tourette disorder than to obsessive-compulsive disorder. REVISTA BRASILEIRA DE PSIQUIATRIA (SAO PAULO, BRAZIL : 1999) 2020; 42:87-104. [PMID: 31576938 PMCID: PMC6986481 DOI: 10.1590/1516-4446-2019-0471] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 06/08/2019] [Indexed: 01/18/2023]
Abstract
OBJECTIVE Trichotillomania (TTM) is characterized by the pulling out of one's hair. TTM was classified as an impulse control disorder in DSM-IV, but is now classified in the obsessive-compulsive related disorders section of DSM-5. Classification for TTM remains an open question, especially considering its impact on treatment of the disorder. In this review, we questioned the relation of TTM to tic disorder and obsessive-compulsive disorder (OCD). METHOD We reviewed relevant MEDLINE-indexed articles on clinical, neuropsychological, neurobiological, and therapeutic aspects of trichotillomania, OCD, and tic disorders. RESULTS Our review found a closer relationship between TTM and tic disorder from neurobiological (especially imaging) and therapeutic standpoints. CONCLUSION We sought to challenge the DSM-5 classification of TTM and to compare TTM with both OCD and tic disorder. Some discrepancies between TTM and tic disorders notwithstanding, several arguments are in favor of a closer relationship between these two disorders than between TTM and OCD, especially when considering implications for therapy. This consideration is essential for patients.
Collapse
Affiliation(s)
- Hugues Lamothe
- Centre Hospitalier Intercommunal de Créteil, Université Paris Est Créteil, Créteil, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U955, Créteil, France
- Fondation FondaMental, Créteil, France
| | - Jean-Marc Baleyte
- Centre Hospitalier Intercommunal de Créteil, Université Paris Est Créteil, Créteil, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U955, Créteil, France
- Fondation FondaMental, Créteil, France
- Université de Caen Normandie (UNICAEN), INSERM, U1077, Caen, France
| | - Luc Mallet
- Fondation FondaMental, Créteil, France
- Assistance Publique Hôspitaux de Paris (APHP), Hôpitaux Universitaires Henri Mondor Albert Chenevier, Université Paris Est Créteil, Créteil, France
- Department of Mental Health and Psychiatry, Geneva University Hospital, University of Geneva, Geneva, Switzerland
- Unité Mixte de Recherche (UMR) S1127, Centre National de la Recherche Scientifique (CNRS), UMR 7225, Institut du Cerveau et de la Moelle Epinière, Paris, France
| | - Antoine Pelissolo
- Institut National de la Santé et de la Recherche Médicale (INSERM), U955, Créteil, France
- Fondation FondaMental, Créteil, France
- Assistance Publique Hôspitaux de Paris (APHP), Hôpitaux Universitaires Henri Mondor Albert Chenevier, Université Paris Est Créteil, Créteil, France
| |
Collapse
|
5
|
Akkermans SEA, van Rooij D, Naaijen J, Forde NJ, Boecker-Schlier R, Openneer TJC, Dietrich A, Hoekstra PJ, Buitelaar JK. Neural reward processing in paediatric Tourette syndrome and/or attention-deficit/hyperactivity disorder. Psychiatry Res Neuroimaging 2019; 292:13-22. [PMID: 31473435 DOI: 10.1016/j.pscychresns.2019.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 07/10/2019] [Accepted: 08/08/2019] [Indexed: 11/19/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is the most common comorbidity in individuals with Tourette syndrome (TS). Yet, it is unclear to what extent TS and ADHD show overlapping or distinct neural abnormalities. ADHD has been associated with altered reward processing, but there are very few studies on reward processing in TS. This study assessed neural activation of basal ganglia and thalamus during reward anticipation and receipt in children with TS and/or ADHD. We analysed mean activations of a priori specified regions of interest during an fMRI monetary incentive delay task. Data was used from 124 children aged 8-12 years (TS n = 47, of which 29 had comorbid ADHD; ADHD n = 29; healthy controls n = 48). ADHD severity across ADHD and TS groups and healthy controls was marginally related to hypoactivation of the right nucleus accumbens during reward anticipation; this effect was not moderated by TS diagnosis. We detected no associations of neural activation with TS. The association between ADHD severity and hypoactivation of the right nucleus accumbens during reward anticipation, independent of the presence or absence of TS, is in line with the view of nucleus accumbens hypoactivation as a dimensional, neurofunctional marker of ADHD severity, transcending the boundaries of primary diagnosis.
Collapse
Affiliation(s)
- Sophie E A Akkermans
- Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Department of Cognitive Neuroscience, Nijmegen, the Netherlands; Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands.
| | - Daan van Rooij
- Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Department of Cognitive Neuroscience, Nijmegen, the Netherlands; Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands
| | - Jilly Naaijen
- Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Department of Cognitive Neuroscience, Nijmegen, the Netherlands; Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands
| | - Natalie J Forde
- Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands; University of Groningen, University Medical Center Groningen, Department of Child and Adolescent Psychiatry, Groningen, the Netherlands
| | - Regina Boecker-Schlier
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Thaira J C Openneer
- University of Groningen, University Medical Center Groningen, Department of Child and Adolescent Psychiatry, Groningen, the Netherlands
| | - Andrea Dietrich
- University of Groningen, University Medical Center Groningen, Department of Child and Adolescent Psychiatry, Groningen, the Netherlands
| | - Pieter J Hoekstra
- University of Groningen, University Medical Center Groningen, Department of Child and Adolescent Psychiatry, Groningen, the Netherlands
| | - Jan K Buitelaar
- Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Department of Cognitive Neuroscience, Nijmegen, the Netherlands; Radboud University, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands; Karakter Child and Adolescent Psychiatry University Centre, Nijmegen, the Netherlands
| |
Collapse
|
6
|
Neuropathology and pathogenesis of extrapyramidal movement disorders: a critical update. II. Hyperkinetic disorders. J Neural Transm (Vienna) 2019; 126:997-1027. [DOI: 10.1007/s00702-019-02030-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/14/2019] [Indexed: 12/14/2022]
|
7
|
Abstract
This is the fourth yearly article in the Tourette Syndrome Research Highlights series, summarizing research from 2017 relevant to Tourette syndrome and other tic disorders. The authors briefly summarize reports they consider most important or interesting. The highlights from 2018 article is being drafted on the Authorea online authoring platform, and readers are encouraged to add references or give feedback on our selections using the comments feature on that page. After the calendar year ends, the article is submitted as the annual update for the Tics collection on F1000Research.
Collapse
Affiliation(s)
- Andreas Hartmann
- Sorbonne University, National Reference Centre for Tourette Disorder, Pitié-Salpêtrière Hospital, Paris, France
| | - Yulia Worbe
- Sorbonne University, National Reference Centre for Tourette Disorder, Pitié-Salpêtrière Hospital, Paris, France
- Department of Physiology, Saint-Antoine Hospital, Paris, France
| | - Kevin J. Black
- Psychiatry, Neurology, Radiology, and Neuroscience, Washington University School of Medicine, St. Louis, MO, 63110-1093, USA
| |
Collapse
|
8
|
Abstract
Tics are the most common movement disorder in childhood and are a frequent reason for referral to child neurology clinics. The purpose of this review is to examine the phenomenology of tics, discuss what is known regarding their genetic and pathophysiological causes and to evaluate current treatment options. The evidence for the evaluation and treatment of the controversial diagnosis of pediatric autoimmune neuropsychiatric disorders associated with group A streptococci (PANDAS) will also be reviewed. With improved understanding of tic disorders, their etiology and response to current treatment options, we may be able to more effectively diagnose them and identify novel treatment strategies.
Collapse
Affiliation(s)
- Joanna S Blackburn
- Division of Child Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago, Northwestern Feinberg School of Medicine, Chicago, IL.
| |
Collapse
|
9
|
Albin RL. Tourette syndrome: a disorder of the social decision-making network. Brain 2018; 141:332-347. [PMID: 29053770 PMCID: PMC5837580 DOI: 10.1093/brain/awx204] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/08/2017] [Accepted: 07/21/2017] [Indexed: 12/11/2022] Open
Abstract
Tourette syndrome is a common neurodevelopmental disorder defined by characteristic involuntary movements, tics, with both motor and phonic components. Tourette syndrome is usually conceptualized as a basal ganglia disorder, with an emphasis on striatal dysfunction. While considerable evidence is consistent with these concepts, imaging data suggest diffuse functional and structural abnormalities in Tourette syndrome brain. Tourette syndrome exhibits features that are difficult to explain solely based on basal ganglia circuit dysfunctions. These features include the natural history of tic expression, with typical onset of tics around ages 5 to 7 years and exacerbation during the peri-pubertal years, marked sex disparity with higher male prevalence, and the characteristic distribution of tics. The latter are usually repetitive, somewhat stereotyped involuntary eye, facial and head movements, and phonations. A major functional role of eye, face, and head movements is social signalling. Prior work in social neuroscience identified a phylogenetically conserved network of sexually dimorphic subcortical nuclei, the Social Behaviour Network, mediating many social behaviours. Social behaviour network function is modulated developmentally by gonadal steroids and social behaviour network outputs are stereotyped sex and species specific behaviours. In 2011 O'Connell and Hofmann proposed that the social behaviour network interdigitates with the basal ganglia to form a greater network, the social decision-making network. The social decision-making network may have two functionally complementary limbs: the basal ganglia component responsible for evaluation of socially relevant stimuli and actions with the social behaviour network component responsible for the performance of social acts. Social decision-making network dysfunction can explain major features of the neurobiology of Tourette syndrome. Tourette syndrome may be a disorder of social communication resulting from developmental abnormalities at several levels of the social decision-making network. The social decision-making network dysfunction hypothesis suggests new avenues for research in Tourette syndrome and new potential therapeutic targets.
Collapse
Affiliation(s)
- Roger L Albin
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
- Neurology Service and GRECC, VAAAHS, Ann Arbor, MI, 48105, USA
- University of Michigan Morris K. Udall Parkinson’s Disease Research Center, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
10
|
Martino D, Ganos C, Worbe Y. Neuroimaging Applications in Tourette's Syndrome. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2018; 143:65-108. [DOI: 10.1016/bs.irn.2018.09.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
11
|
Premonitory urges and tics in Tourette syndrome: computational mechanisms and neural correlates. Curr Opin Neurobiol 2017; 46:187-199. [PMID: 29017141 DOI: 10.1016/j.conb.2017.08.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/01/2017] [Accepted: 08/21/2017] [Indexed: 12/22/2022]
Abstract
Tourette syndrome is characterized by open motor behaviors - tics - but another crucial aspect of the disorder is the presence of premonitory urges: uncomfortable sensations that typically precede tics and are temporarily alleviated by tics. We review the evidence implicating the somatosensory cortices and the insula in premonitory urges and the motor cortico-basal ganglia-thalamo-cortical loop in tics. We consider how these regions interact during tic execution, suggesting that the insula plays an important role as a nexus linking the sensory and emotional character of premonitory urges with their translation into tics. We also consider how these regions interact during tic learning, integrating the neural evidence with a computational perspective on how premonitory-urge alleviation reinforces tics.
Collapse
|
12
|
Maia TV, Conceição VA. The Roles of Phasic and Tonic Dopamine in Tic Learning and Expression. Biol Psychiatry 2017; 82:401-412. [PMID: 28734459 DOI: 10.1016/j.biopsych.2017.05.025] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/08/2017] [Accepted: 05/28/2017] [Indexed: 01/26/2023]
Abstract
Tourette syndrome (TS) prominently involves dopaminergic disturbances, but the precise nature of those disturbances has remained elusive. A substantial body of empirical work and recent computational models have characterized the specific roles of phasic and tonic dopamine (DA) in action learning and selection, respectively. Using insights from this work and models, we suggest that TS involves increases in both phasic and tonic DA, which produce increased propensities for tic learning and expression, respectively. We review the evidence from reinforcement-learning and habit-learning studies in TS, which supports the idea that TS involves increased phasic DA responses; we also review the evidence that tics engage the habit-learning circuitry. On the basis of these findings, we suggest that tics are exaggerated, maladaptive, and persistent motor habits reinforced by aberrant, increased phasic DA responses. Increased tonic DA amplifies the tendency to execute learned tics and also provides a fertile ground of motor hyperactivity for tic learning. We review evidence suggesting that antipsychotics may counter both the increased propensity for tic expression, by increasing excitability in the indirect pathway, and the increased propensity for tic learning, by shifting plasticity in the indirect pathway toward long-term potentiation (and possibly also through more complex mechanisms). Finally, we review evidence suggesting that low doses of DA agonists that effectively treat TS decrease both phasic and tonic DA, thereby also reducing the propensity for both tic learning and tic expression, respectively.
Collapse
Affiliation(s)
- Tiago V Maia
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.
| | - Vasco A Conceição
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| |
Collapse
|