Assessment of Biomedical Research on Tourette syndrome

Assessmentof Biomedical Research on Tourette syndrome

Assessmentof Biomedical Research on Tourette syndrome

“Gillesde la Tourette syndrome,’’ is the clinical name given to Tourettesyndrome (TS), named after French neurologist who described it interms of neurological and behavioral disorder. TS is a commonchildhood-onset neurobehavioral disorder that is the primary ticdisorder that reaches most commonly medical attention and monitoring.It is characterized by multiple motor and phonic tics affecting boysmore frequently than girls and mostly attacks members aged betweenfive and eighteen years of age. Tics in Tourette syndrome display apeculiar variability over time where they begin in childhood andthey persist until early adulthood but they are at peak in earlyadolescence. Tics are spontaneous, repetitive, typecast behaviorsthat come about within a limited duration, frequently and normallymany times in a single day. The degree of the syndromes effect on anindividual differs from person to another, ranging from mild cases tomore complex and severe cases of TS. The syndrome can last a lifetimewithout diagnosis but there has been an observation that in earlyteen years, people with TS experience the worst form of tic symptomsonly to seize in late teens and adulthood.

Inan effort to understand TS, several biomedical researches have been carried out regarding the methods of diagnosis, sampling of the ticsymptoms, as well as prescribing treatment strategies for thesyndrome. The diagnosis of the syndrome has been a challenge over theyears since there are no specific screening tests used for thesyndrome’s diagnosis. Thus, TS is diagnosed on the basis ofobservation of the individual’s symptoms over a period of time.There are no clear symptoms which must be seen to diagnose someonewith the syndrome. The researchers also look into the possible causesof the tics and associated disorders such as inattention,hyperactivity and impulsivity (ADHD), problems in reading, and otherrepetitive behaviors.

Mechanismspromoting Tourette syndrome

Tourettesyndrome is associated with several disorders such as attentiondeficit hyperactivity disorder (ADHD), Obsessive Compulsive Disorder(OCD), poor impulses control, and other behavioral practices whichindividuals do repetitively and over a long period of time. Tics areabrupt, swift, recurring non-rhythmic motor movements involvingmuscles or phonics ones which are associated with sound. According toJankorvic and Kurlan1,a definite diagnosis of the Tourette syndrome involves observation ofboth multiple motor tics and one or more phonic tics at a certainperiod during the sickness. These tics must also be occurring manytimes a day and occur over one year without a window of more thanthree months without these symptoms. For correct diagnosis of TS thetics symptoms must be occurring at the period before eighteen yearsof age and they shouldn’t be brought by other medical conditions orphysiological effects of a substance1,2.

Themajor tic disorders are regarded to as multifactorial conditions andare said to exhibit neurodevelopmental conditions, which is known tocharacterize the TS. Tics can be simple or complex sine there aredifferent causes which portrays different underlying mechanism.Simple tics involve a single muscle group producing brief movementsand sounds. They can be in terms of eye blinking, lip movement,grimacing, shoulder shrugs, throat clearing, rapid limb movement andmany others. Complex tics appear as coordinated muscle contractionsinvolving different muscles groupings2.They can be appearing simultaneously or in very frequent rapidsuccession movements. Different individuals portray variant complextics movements including complex head movement, bending, limb andtorso movements, pronouncing words or phrases among other symptoms.These complex tics can be hard to separate from compulsions, anothercondition evidenced to be closely associated to the syndrome2.

Thecurrent interests based on the Tourette syndrome is trying toidentify the fundamental psychological disturbances that underlie thefull clinical diagnosis of the syndrome. Suppressibility of the ticsis a feature commonly observed in TS with the degree of suppressionvarying across individuals as well as age of the subjects2,3.Active suppression deprives the ability of the subjects toconcentrate and makes them shift their focus from mentalattention-demanding tasks, which causes intensity and discomfort onthe subjects. This inattention is as a result of impulse control dueto motor and behavioral manifestations of the syndrome1.The changes in suppression intensity also varies due the environmentcontext of the subjects. Exposure to psychological or socialstressors such as stress, anxiety, fatigues, or even exciting momentsmay increase the severity of the tics. When subjects engage inactivities that are demanding more attention or get into generalphysical practices, the symptoms of the tic may be considerablysuppressed.

Thenature and occurrence of tics is also variant depending on severalfactors which makes their occurrence either suggestible or naturallyreflective and thus occur abruptly. Majority of the tics in adultsrepresents recurrent childhood occurrences. In the researches aimedat demystifying these occurrences, it has been revealed that thetemporal incidences of tics follow a designated condition where theyare clustered in bouts of tics which appears in a sessional moment ina period of time2-4.Due to their history definiteness, the tics emerge at the age of fiveyears up to eight years for many of the subjects. Most cases theonset is characterized by simple tics but over time, the incidencesof complex tics surface over time during the disorder. Repetitivebehaviors are also core features of TS and they are defined bydifferent phenomena. Echophenomena are involuntary repetitivebehaviors or imitation of other person’s gestures or words. Despitebeing an acceptable normal occurrence for children below the age ofthree, the behavior at later ages indicate the lack of control inaction and imitation control mechanisms4,5.This phenomenon is characteristic of TS. Coprophenomena is expressionof socially unacceptable words or gestures of obscene, profaneethnicity insulting content due to anger or in emphasizing (StephenR. Jackson et al.). These and other more specific cases are importanttowards evaluation and diagnosis of Tourette syndrome. Emphasisshould be instituted when dealing with psychosocial factors andneuropsychiatric conditions when the subject is being diagnosed forthe syndrome. The complexity of the syndrome is increasing and manyresearchers are proposing that there is no single phenotype ofGeorges Gilles de la Tourette syndrome. Several studies have poisedthe suggestion of variant conditions for the syndrome1-3,7.

Experimentalstudies on Tourette syndrome

Asa neuropsychiatric disorder, the Tourette syndrome has attracted anumber of studies that are put forward to study the dynamics of thetics and their behavior among affected subjects. In these studies,the researchers explain some of the phenomena associated with thedisorders while in others there is a suggestion of one or moretherapy theories for taking care of TS patients. In understanding thesyndrome, there is a focus on the symptoms that are mostly observedin psychiatric patients with the Tourette syndrome2,5. In a study to test the efficacy of a comprehensive behavioralinteraction for tics in children and adults, Wilhelm et al.5observed that comprehensive behavioral therapy is a safe andeffective intervention for adults with the Tourette syndrome. Thedisorder is characterized by persistent tics and is common to everysix children out of 100. The prevalence of this disease is, however,lower in adults as compared to children. For adults ailing from thedisorder, thy may be more acutely affected if other hypersensitivitydisorder happen to them than those without other disorders such asADHD. The resulting effect of the syndrome to adults is, in mostcases, the onset of disabilities associated to it. In a study byJackson et al.6,TS is defined as following a progressive time course associated withincrease in control over tics, which is accompanied by compensatory,neoplastic, alterations in the structure of the brain for most of theaffected subjects. Majority of individuals with tics develop a meansof regulating and are thus able to effectively suppress their tics byearly adulthood or their late teen years6.Only a small section of few subjects do carry these symptoms intoadulthood and throughout their life.

Thecontrol over tics may come over due to induced practices or thevoluntary cortical connectivity practices. These practices can beshort range, which indicates that the cortical excitability within abrain might be altered through changes in the operation of neuralcircuits such as the inhibitory interneurons4,6.These phenomena then functions as the suppressing regulators of thecortical excitability in the local brain either in a general contextor for a task-specific concentration area. The long range complete ofthis phenomenon is the outcome of enhanced control over motor outputsthat bring about the tics symptoms. Individuals with the syndromegain control over their tics by developing compensatoryself-regulation mechanisms effected through changes in neural pathsthat link frontal cortex with primary and secondary motor regions ofthe human brain6.This observation suggests a possibility that alterations of patternsof control over motor outputs in TS can result due to the changes inlong-range and short-range cortical connectivities. Other studies inthe area of research suggest that GABA-mediated schemes are involvedin the dysfunctional mechanisms at the cortical as well assubcortical level. The dysfunction leads to disturbances in the motorfunction and the sensorimotor gating. At the level of the primarymotor cortex, short-interval intracortical inhibition – associatedwith neural activity in the mediated systems and circuits. Thisassociation has also being used to show that children with thesyndrome but are in a resting condition are considered to be lessaffected by tics since they exhibit less severe symptoms of thedisorder. Consequently, subjects with the syndrome are not affectedby the tics when they are in deep sleep.

Thecapability to produce suitable behavioral reactions to internal orthe external environmental demands as well as to adapt behaviorconstantly rendering to these varying conditions is an indispensablenecessity. For any individual to survive functionally in the day byday life, and to enhance the social acceptability of that individual,one must possess these capabilities. One known effect of the syndromeis the abnormalities it brings along in respect to behavioral controlmostly to those associated to the frontal cortical functions7.While studying the altered modulation of intracortical excitabilityduring movement preparation for tics in TS subjects, Heise et al.7observed that pre-movement tics correlates negatively with earlydisinhibiting of the cortical fronts. The study is in consistencywith the supposition that reduction in intra-cortical inhibition, andhyper-excitability within motor cortex in TS, is correlated withclinical measurements of tic severity and frequency of occurrence.

Anotherrecent study suggests that counterfactual thinking deficit isassociated to the Tourette syndrome and that the deficiency mustoccur at one point over the course of the disorder. Counterfactualthinking is the capacity to “do otherwise” in situations thatcalls for alternative solutions to issues in a reasonable manner.This capability is associated influenced by the mind’s aptitude tomentally characterize likely behaviors and apparent scenarios thatare likely to arise. The underlying fact about this phenomenon is animportant role in the cognitive functioning of an individual in dayby day living. It is connected to a wide range of psychological andbehavioral processes associated with the prefrontal lobe whichinclude the art of decision-making, planning, problem-solving, andexperience-driven learning. This ability is deficient to people withthe syndrome.

Thecurrent research on TS include genetic studies to establish thegenetic risk factors, strengthen clinical diagnosis, improve geneticcounseling, and provide clues for more effective therapies.Neuroimaging studies are trying to establish the conditionsprevailing in the brain for people with TS and related conditions.Several clinical trials have also been undertaken including studiesof stimulant treatment of ADHD in TS and behavioral treatments forreducing tic severity in children and adults6,7,9.

TreatmentsAssociated with Tourette syndrome

TheAmerican psychiatric association and other organizations has endorsedthe use of antipsychotic medications haloperidol and pimozide for thetreatment of tics in TS. Since tic symptoms are not known to causeany impairment, the majority of the TS syndrome subjects need notreatment for tic suppression, which can actually occur naturally forsome patients. However, these effective medicines are accessible forthe patients, particularly most of those whose symptoms interferewith functioning and their day by day life. The two medications areneuroleptic drugs used to treat psychotic and non-psychotic disorderssince they are the most reliably convenient prescriptions for ticsuppression of the syndrome-associated tics. The uncommonantipsychotic risperidone is also effective in reduction of the ticssymptoms. Regrettably, there is none of the medications that isadequately helpful to all those diagnosed with the syndrome andneither do any of these medications entirely eradicate the ticssymptoms they only suppresses them.

Itis common that all medications have side effects and the abovementioned are no different. Most of the patients prescribed withthese medication often complain of side effects which includesedation, weight gain, and cognitive dulling, tremor, dystonicreactions, parkinsonian-like symptoms, and other involuntarymovements. Withdrawing from antipsychotic drugs after long-termshould be done slowly since abrupt stoppage is associated withincrease in tics. The risks of these side effects can be reduced byusing lower doses of antipsychotic for short episodes of timeintermittently over the course of the disorder.

Otherpharmacotherapy medications can also be used in suppressing ticsymptoms severity, but most of these have not been as broadly studiedor regarded as reliably useful as neuroleptics or antipsychoticmedicines. Supplementary medications used in treatment of ticssymptoms include clonidine and guanfacine, which are largely forhypertension but are also prescribed for the treatment of TSsymptoms. Theses medicines are also regarded as lesser side-effectingand are thus mostly used before introducing antipsychotic drugsdescribed earlier. Some medications are used to treat some of theassociated neurobehavioral disorders, such as ADHD, that can occur inpatients with TS. Researchers have it in their ego that futurestudies will incorporate a detailed argument of the risks andbenefits of stimulant treatment for those with TS. Several inhibitorshave also been indicated as remedies to some of the complicationsarising from the syndrome.

Behavioraltreatments, whose use has been controversial, such as awarenesstraining and competing response training can also be used to reducetics. Cognitive Behavioral Intervention for Tics9,revealed that, training to voluntarily move as a response to apremonitory urge effectively reduces tic symptoms for most of theTourette syndrome subjects.Other behavioral therapies, such asbiofeedback or supportive therapy, have not been shown to reduce ticsymptoms and this has brought about many arguments about theeffectiveness of behavioral therapy for TS patients. Nonetheless,supportive therapy assists a person with the syndrome better copewith the disorder and the associated tics symptoms.

Summary

TheTourette syndrome has been a crucial objective for research inneurologic disorders since its initial description in 1885 by theFrenchman psychiatrist. The studies conducted in this field hasindicated that understanding the disorder is key in diagnosing andcaring for the subject carriers affected by the disorder. Thissyndrome is diagnosed on the basis of observation of the individual’ssymptoms over a period of time. There are no clear symptoms whichmust be seen to diagnose someone with the syndrome. TS is associatedwith behavioral and involuntary tics, which can be phonic or motor,and happens to occur in different forms from one patient to another.Treatment of these symptoms is mostly by suppressing them.Suppressibility of the tics is a feature commonly observed in TS andthe degree of suppression varies across individuals depending onseveral social factors such as sex and age of the subjects.

Activetics deprives the ability of the subjects to concentrate and makesthem shift their focus from mental attention-demanding tasks, whichcauses intensity and discomfort on the subjects. Their suppressionrestores the freedom of control to the subjects. Although there is nocure for the syndrome, the disorder in many individuals diminishes inthe late teens and early adulthood, though in some it persists toadulthood. It is thus a common occurrence that some patients mayactually become symptom-free and thus they no longer need medicationfor tic suppression since they are in control. In conclusion, recentstudies have indicated that the syndrome is associated to a mixedpattern of preserved and impaired performances on social cognitiontests and thus, further studies are needed. They should help us tobetter understand the contribution of social aspects to everydayfunctioning, especially in childhood and adolescence with thesyndrome since they are the most adversely affected when the tics areat their peak.

References

  1. Jankovic, J. and Kurlan, R. (2011). Tourette syndrome: Evolving concepts. Movement Disorders, 26: 1149–1156. doi: 10.1002/mds.23618

  2. Martino D, Madhusudan N, Zis P, Cavanna AE. An introduction to the clinical phenomenology of Tourette syndrome International Review of Neurobiology . 2013 112:1-33.

  3. Aron, A. R., Robbins, T. W., &amp Poldrack, R. A. (2004). Inhibition and the right inferior frontal cortex. Trends in cognitive sciences, 8(4), 170-177.

  4. Zago S, Delli Ponti A, Mastroianni S, Solca F, Tomasini E, Poletti B, Inglese S, Sartori G, Porta M. Counterfactual Thinking in Tourette`s Syndrome: A Study Using Three Measures, Behavioural Neurology. 2014 2014256089

  5. Wilhelm S, Peterson AL, Piacentini J, et al. Randomized Trial of Behavior Therapy for AdultsWith Tourette Syndrome. Arch Gen Psychiatry. 201269(8):795-803. doi:10.1001/archgenpsychiatry.2011.1528

  6. Jackson SR, Parkinson A, Manfredi V, Millon G, Hollis C, Jackson GM. Motor excitability is reduced prior to voluntary movements in children and adolescents with Tourette syndrome, Journal of Neuropsychology. 2013 Mar 7(1):29-44. Epub 2012 Jul 16.

  7. Heise KF, Steven B, Liuzzi G, Thomalla G, Jonas M, Müller-Vahl K, Sauseng P, Münchau A, Gerloff C,. Altered modulation of intracortical excitability during movement preparation in Gilles de la Tourette syndrome, Hummel FC. Brain. 2010 Feb 133(Pt 2):580-90. Epub 2009 Dec 11.

  8. Jackson S. R., Parkinson A., Jung J., Ryan S. E., Morgan P. S., Hollis C., Jackson G. M. Compensatory neural reorganization in Tourette syndrome. Current Biology. 201121(7):580–585. doi: 10.1016/j.cub.2011.02.047

  9. Piacentini, J., Woods, D. W., Scahill, L., Wilhelm, S., Peterson, A. L., Chang, S., … &amp Walkup, J. T. (2010). Behavior therapy for children with Tourette disorder: a randomized controlled trial. Jama, 303(19), 1929-1937.