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Banca P, Herrojo Ruiz M, Gonzalez-Zalba MF, Biria M, Marzuki AA, Piercy T, Sule A, Fineberg NA, Robbins TW. Action sequence learning, habits, and automaticity in obsessive-compulsive disorder. eLife 2024; 12:RP87346. [PMID: 38722306 PMCID: PMC11081634 DOI: 10.7554/elife.87346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024] Open
Abstract
This study investigates the goal/habit imbalance theory of compulsion in obsessive-compulsive disorder (OCD), which postulates enhanced habit formation, increased automaticity, and impaired goal/habit arbitration. It directly tests these hypotheses using newly developed behavioral tasks. First, OCD patients and healthy participants were trained daily for a month using a smartphone app to perform chunked action sequences. Despite similar procedural learning and attainment of habitual performance (measured by an objective automaticity criterion) by both groups, OCD patients self-reported higher subjective habitual tendencies via a recently developed questionnaire. Subsequently, in a re-evaluation task assessing choices between established automatic and novel goal-directed actions, both groups were sensitive to re-evaluation based on monetary feedback. However, OCD patients, especially those with higher compulsive symptoms and habitual tendencies, showed a clear preference for trained/habitual sequences when choices were based on physical effort, possibly due to their higher attributed intrinsic value. These patients also used the habit-training app more extensively and reported symptom relief post-study. The tendency to attribute higher intrinsic value to familiar actions may be a potential mechanism leading to compulsions and an important addition to the goal/habit imbalance hypothesis in OCD. We also highlight the potential of smartphone app training as a habit reversal therapeutic tool.
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Affiliation(s)
- Paula Banca
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
- Behavioural and Clinical Neuroscience Institute, University of CambridgeCambridgeUnited Kingdom
| | - Maria Herrojo Ruiz
- Department of Psychology, Goldsmiths University of LondonLondonUnited Kingdom
| | | | - Marjan Biria
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
- Behavioural and Clinical Neuroscience Institute, University of CambridgeCambridgeUnited Kingdom
| | - Aleya A Marzuki
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
- Behavioural and Clinical Neuroscience Institute, University of CambridgeCambridgeUnited Kingdom
| | - Thomas Piercy
- Department of Psychiatry, School of Clinical Medicine, University of CambridgeCambridgeUnited Kingdom
| | - Akeem Sule
- Department of Psychiatry, School of Clinical Medicine, University of CambridgeCambridgeUnited Kingdom
| | - Naomi A Fineberg
- Hertfordshire Partnership University NHS Foundation TrustWelwyn Garden CityUnited Kingdom
- University of HertfordshireHatfieldUnited Kingdom
| | - Trevor W Robbins
- Department of Psychology, University of CambridgeCambridgeUnited Kingdom
- Behavioural and Clinical Neuroscience Institute, University of CambridgeCambridgeUnited Kingdom
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Li Y, Woods DW, Gu Y, Yu L, Yan J, Wen F, Wang F, Liu J, Cui Y. Psychometric Properties of the Chinese Version of the Premonitory Urge for Tics Scale: A Preliminary Report. Front Psychol 2021; 12:573803. [PMID: 34646181 PMCID: PMC8503313 DOI: 10.3389/fpsyg.2021.573803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 08/26/2021] [Indexed: 12/27/2022] Open
Abstract
Premonitory urges (PUs) are sensory phenomena that immediately precede tics. The Premonitory Urge for Tics Scale (PUTS) is widely used to assess the severity of PUs, but the psychometric properties of PUTS and clinical features of PU in Chinese patients with tic disorders are still unclear. In this study, we examined the psychometric properties of the Chinese version of the PUTS in a large sample (including 367 Chinese pediatric patients with tic disorders). We found no difference in PU in different age groups. The exploratory factor analysis (EFA) of PUTS showed the emergence of four primary factors. The results of reliability and validity analyses indicated that the Chinese version showed good psychometric properties. It seemed that PU was associated with the severity of obsession symptoms in patients with tic disorders. Network analysis showed that Item 7 is a critical node for the PU, in addition to Items 1 and 4. Overall, the Chinese version of PUTS can be used in Chinese child and adolescent patients with tic disorders, particularly for patients with Tourette syndrome.
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Affiliation(s)
- Ying Li
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Douglas W Woods
- Department of Psychology, Marquette University, Milwaukee, WI, United States
| | - Yi Gu
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Liping Yu
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Junjuan Yan
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Fang Wen
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Fang Wang
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Jingran Liu
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Yonghua Cui
- Department of Psychiatry, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
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Nomura Y. Pharmacological therapy for Tourette syndrome: What medicine can do and cannot do. Biomed J 2021; 45:229-239. [PMID: 34547532 PMCID: PMC9250092 DOI: 10.1016/j.bj.2021.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/24/2021] [Accepted: 09/09/2021] [Indexed: 11/23/2022] Open
Abstract
Tourette syndrome (TS) is a frequently observed developmental neuropsychological disorder occurring in children. The pathophysiology involves both genetic and environmental factors. In this review, clinical characteristics, pathophysiology, and treatment approaches based on the pathophysiology of TS are presented. The pathophysiology is the acceleration of developmental decrement of dopamine (DA) activity at the terminal of nigro-striatal (NS)-DA system causing DA D2 receptor up-ward regulation. Serotonergic neurons involving in development of the biphasic sleep-wake-rhythm, and locomotion may be involved. Pharmacological treatments constitute an important part in managing TS. Small dose of levodopa and aripiprazole showed the good effect controlling the tics, without side effects. Intervention with enhancing the day time activity and keeping the regular sleep-wake-rhythm, and encouraging locomotion are important. The data from Yoshiko Nomura Neurological Clinic for Children regarding the clinical features and outcomes, medication effects, and OCD and outcomes are shown. To discuss about the environmental factor, how the COVID-19 pandemic affected the TS patients is also presented.
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Affiliation(s)
- Yoshiko Nomura
- Neurological Clinic for Children, Tokyo Japan, Address: Ochanomizu-Myojin Building 3(rd) Floor, 1-2-13 Yushima Bunkyoku Tokyo, 113-0034, Japan,.
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Yu L, Li Y, Zhang J, Yan C, Wen F, Yan J, Wang F, Liu J, Cui Y. The therapeutic effect of habit reversal training for Tourette syndrome: a meta-analysis of randomized control trials. Expert Rev Neurother 2020; 20:1189-1196. [PMID: 32948114 DOI: 10.1080/14737175.2020.1826933] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVES Comprehensive behavioral intervention for tics (CBIT) and habit reversal training (HRT) are forms of cognitive behavioral therapy that can effectively reduce tic symptoms in patients with tic disorders, but their efficacies and potential moderators were needed to be clarified. METHODS In the present study, a meta-analysis was performed to identify the efficacy of HRT and CBIT for individuals with tic disorders. The standard mean difference (SMD) was calculated to assess the effect size of the efficacy of HRT. Subgroup analysis and meta-regression analysis were performed to identify the potential heterogeneity of the SMD of HRT. RESULTS A total of 10 randomized controlled trials (RCTs) including 586 patients with tic disorders were identified. The pooled SMD was -0.43 (95% CI: -0.71, -0.16). The effect size of HRT was moderated by different 'Comparison Conditions' (it means the different behavioral therapies in the control group). CONCLUSION Overall, the authors found a small to medium effect size for the efficacy of HRT. As the most promising behavioral therapy, they conclude that HRT is effective for the treatment of patients with tic disorders. Further high-quality RCTs are needed to determine the efficacy of HRT compared with that of medications.
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Affiliation(s)
- Liping Yu
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Ying Li
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Jishui Zhang
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Chunmei Yan
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Fang Wen
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Junjuan Yan
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Fang Wang
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Jingran Liu
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
| | - Yonghua Cui
- Department of Psychiatry, Beijing Children's Hospital, Capital Medical University, National Center for Children Healthy , Beijing, China
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Heinicke MR, Stiede JT, Miltenberger RG, Woods DW. Reducing risky behavior with habit reversal: A review of behavioral strategies to reduce habitual hand-to-head behavior. J Appl Behav Anal 2020; 53:1225-1236. [PMID: 32686131 PMCID: PMC7404378 DOI: 10.1002/jaba.745] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 12/03/2022]
Abstract
Habit reversal training (HRT) has been a mainstay of behavior analysts' repertoire for nearly the last 50 years. HRT has been effective in treating a host of repetitive behavior problems. In the face of the current coronavirus pandemic, HRT has practical public health importance as a possible intervention for reducing hand‐to‐head behaviors that increase the risk of viral infection. The current paper provides a brief review of HRT for hand‐to‐head habits that is designed for a broad audience and concludes with practical suggestions, based on HRT, for reducing face‐touching behaviors.
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Deeb W, Malaty IA, Mathews CA. Tourette disorder and other tic disorders. HANDBOOK OF CLINICAL NEUROLOGY 2019; 165:123-153. [DOI: 10.1016/b978-0-444-64012-3.00008-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Viefhaus P, Feldhausen M, Görtz-Dorten A, Volk H, Döpfner M, Woitecki K. Efficacy of Habit Reversal Training in Children With Chronic Tic Disorders: A Within-Subject Analysis. Behav Modif 2018; 44:114-136. [PMID: 30146896 DOI: 10.1177/0145445518796203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The aim of this study is to evaluate a cognitive-behavioral treatment for children and adolescents with tic disorder including habit reversal training (HRT) in a sample of children and adolescents (n = 27). Multiple outcome measures were used to assess the effects of the treatment on tic symptoms. In addition, impairment/subjective burden ratings and the self-efficacy to control tics were assessed. A within-subject design with two phases (8 weeks diagnostic; 16 sessions treatment) was analyzed using multilevel modeling (MLM). During the treatment phase, significant improvements in tic symptoms, impairment, and self-efficacy to control tics were found on most outcome measures. Treatment effects were found on the clinical rating of tic symptoms (Yale Global Tic Severity Scale [YGTSS]), the self-efficacy to control tics, and the video-observed motor tic frequency by comparing the improvements during treatment with the course of the outcome measures during the preceding diagnostic phase.
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Affiliation(s)
- Paula Viefhaus
- School of Child and Adolescent Cognitive Behavior Therapy (AKiP), University Hospital, Cologne, Germany
| | - Marion Feldhausen
- School of Child and Adolescent Cognitive Behavior Therapy (AKiP), University Hospital, Cologne, Germany
| | - Anja Görtz-Dorten
- School of Child and Adolescent Cognitive Behavior Therapy (AKiP), University Hospital, Cologne, Germany.,Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University of Cologne, Germany
| | - Helene Volk
- School of Child and Adolescent Cognitive Behavior Therapy (AKiP), University Hospital, Cologne, Germany
| | - Manfred Döpfner
- School of Child and Adolescent Cognitive Behavior Therapy (AKiP), University Hospital, Cologne, Germany.,Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University of Cologne, Germany
| | - Katrin Woitecki
- School of Child and Adolescent Cognitive Behavior Therapy (AKiP), University Hospital, Cologne, Germany
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McDiarmid TA, Bernardos AC, Rankin CH. Habituation is altered in neuropsychiatric disorders-A comprehensive review with recommendations for experimental design and analysis. Neurosci Biobehav Rev 2017; 80:286-305. [PMID: 28579490 DOI: 10.1016/j.neubiorev.2017.05.028] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 05/29/2017] [Indexed: 02/03/2023]
Abstract
Abnormalities in the simplest form of learning, habituation, have been reported in a variety of neuropsychiatric disorders as etiologically diverse as Autism Spectrum Disorder, Fragile X syndrome, Schizophrenia, Parkinson's Disease, Huntington's Disease, Attention Deficit Hyperactivity Disorder, Tourette's Syndrome, and Migraine. Here we provide the first comprehensive review of what is known about alterations in this form of non-associative learning in each disorder. Across several disorders, abnormal habituation is predictive of symptom severity, highlighting the clinical significance of habituation and its importance to normal cognitive function. Abnormal habituation is discussed within the greater framework of learning theory and how it may relate to disease phenotype either as a cause, symptom, or therapy. Important considerations for the design and interpretation of habituation experiments are outlined with the hope that these will aid both clinicians and basic researchers investigating how this simple form of learning is altered in disease.
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Affiliation(s)
- Troy A McDiarmid
- Graduate Program in Neuroscience, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Rm F221, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada
| | - Aram C Bernardos
- Graduate Program in Neuroscience, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Rm F221, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada
| | - Catharine H Rankin
- Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, V6T 1Z4, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Rm F221, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada.
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Interventions for tic disorders: An overview of systematic reviews and meta analyses. Neurosci Biobehav Rev 2016; 63:239-55. [PMID: 26751711 DOI: 10.1016/j.neubiorev.2015.12.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 11/24/2015] [Accepted: 12/28/2015] [Indexed: 02/05/2023]
Abstract
We conducted a comprehensive search and the overview included 22 systematic reviews (SRs) for treating tic disorders (TDs). Three SRs indicated typical antipsychotics (i.e., haloperidol, pimozide) were efficacious in the reduction of tic severity compared with placebo but with poor tolerability. Six SRs assessed the efficacy of atypical antipsychotics and indicated that atypical antipsychotics (i.e., risperidone, aripiprazole) could significantly improved tic symptoms compared with placebo or typical antipsychotics with less AEs. Four SRs indicated alpha adrenergic agonists (i.e., clonidine, guanfacine) could improve tic symptoms. Two SRs assessed the efficacy of antiepileptic drugs and indicated topiramate was a promising therapy. Six SRs evaluated the efficacy of behavior therapy and showed habit reversal therapy (HRT) and exposure and response prevention (ERP) were effective. One SR evaluated the efficacy deep brain stimulation (DBS) and indicated DBS is a promising treatment option for severe cases of TS. In conclusion, RCTs directly comparing different pharmacological treatment options are scarce. In practice, typical and atypical antipsychotics are often considered firstly while other pharmacological medications are suggested as alternatives in the case of treatment failure or contradictory outcomes. Behavioral therapies can be used either alone or in combination with medication.
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Leclerc JB, O'Connor KP, J-Nolin G, Valois P, Lavoie ME. The Effect of a New Therapy for Children with Tics Targeting Underlying Cognitive, Behavioral, and Physiological Processes. Front Psychiatry 2016; 7:135. [PMID: 27563292 PMCID: PMC4980689 DOI: 10.3389/fpsyt.2016.00135] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 07/19/2016] [Indexed: 11/29/2022] Open
Abstract
Tourette disorder (TD) is characterized by motor and vocal tics, and children with TD tend to present a lower quality of life than neurotypical children. This study applied a manualized treatment for childhood tics disorder, Facotik, to a consecutive case series of children aged 8-12 years. The Facotik therapy was adapted from the adult cognitive and psychophysiological program validated on a range of subtypes of tics. This approach aims to modify the cognitive-behavioral and physiological processes against which the tic occurs, rather than only addressing the tic behavior. The Facotik therapy lasted 12-14 weeks. Each week 90-min session contained 20 min of parental training. The therapy for children followed 10 stages including: awareness training; improving motor control; modifying style of planning; cognitive and behavioral restructuring; and relapse prevention. Thirteen children were recruited as consecutive referrals from the general population, and seven cases completed therapy and posttreatment measures. Overall results showed a significant decrease in symptom severity as measured by the YGTSS and the TSGS. However, there was a discrepancy between parent and child rating, with some children perceiving an increase in tics, possibly due to improvement of awareness along therapy. They were also individual changes on adaptive aspects of behavior as measured with the BASC-2, and there was variability among children. All children maintained or improved self-esteem posttreatment. The results confirm the conclusion of a previous pilot study, which contributed to the adaptation of the adult therapy. In summary, the Facotik therapy reduced tics in children. These results underline that addressing processes underlying tics may complement approaches that target tics specifically.
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Affiliation(s)
- Julie B Leclerc
- Centre d'études troubles obsessionnels-compulsifs et tics, Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Montreal, QC, Canada; Laboratoire d'étude des troubles de l'ordre de la psychopathologie en enfance, Département de psychologie, Université du Québec à Montréal, Montreal, QC, Canada
| | - Kieron P O'Connor
- Centre d'études troubles obsessionnels-compulsifs et tics, Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Montreal, QC, Canada; Département de Psychiatrie, Université de Montréal, Montreal, QC, Canada
| | - Gabrielle J-Nolin
- Centre d'études troubles obsessionnels-compulsifs et tics, Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Montreal, QC, Canada; Laboratoire d'étude des troubles de l'ordre de la psychopathologie en enfance, Département de psychologie, Université du Québec à Montréal, Montreal, QC, Canada
| | - Philippe Valois
- Centre d'études troubles obsessionnels-compulsifs et tics, Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Montreal, QC, Canada; Laboratoire d'étude des troubles de l'ordre de la psychopathologie en enfance, Département de psychologie, Université du Québec à Montréal, Montreal, QC, Canada
| | - Marc E Lavoie
- Centre d'études troubles obsessionnels-compulsifs et tics, Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Montreal, QC, Canada; Département de Psychiatrie, Université de Montréal, Montreal, QC, Canada; Laboratoire de Psychophysiologie Cognitive et Sociale, Montreal, QC, Canada
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Exposure and Response Prevention and Habit Reversal Training: Commonalities, Differential Use, and Combined Applications. JOURNAL OF CONTEMPORARY PSYCHOTHERAPY 2013. [DOI: 10.1007/s10879-013-9234-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Theoretical and practical considerations behind the use of laboratory animals for the study of Tourette syndrome. Neurosci Biobehav Rev 2013; 37:1085-100. [PMID: 23583771 DOI: 10.1016/j.neubiorev.2013.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/19/2013] [Accepted: 03/23/2013] [Indexed: 12/18/2022]
Abstract
In the present manuscript we review a substantial body of literature describing several pre-clinical animal models designed and developed with the purpose of investigating the biological determinants of Tourette syndrome (TS). In order to map the animal models onto the theoretical background upon which they have been devised, we first define phenomenological and etiological aspects of TS and then match this information to the available pre-clinical models. Thus, we first describe the characteristic symptoms exhibited by TS patients and then a series of hypotheses attempting to identify the multifactorial causes of TS. With respect to the former, we detail the phenomenology of abnormal repetitive behaviors (tics and stereotypies), obsessive-compulsive behaviors and aberrant sensory-motor gating. With respect to the latter, we describe both potential candidate vulnerability genes and environmental factors (difficult pregnancies, psychosocial stressors and infections). We then discuss how this evidence has been translated in pre-clinical research with respect to both dependent (symptoms) and independent (etiological factors) variables. Thus, while, on the one hand, we detail the methodologies adopted to measure abnormal repetitive and obsessive-compulsive behaviors, and sensory-motor gating, on the other hand, we describe genetic engineering studies and environmental modulations aimed at reproducing the proposed biological determinants in laboratory rodents. A special emphasis is placed upon "programming" events, occurring during critical stages of early development and exerting organizational delayed consequences. In the final section, we outline a heuristic model with the purpose of integrating clinical and pre-clinical evidence in the study of TS.
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