Familial And Genetic Findings
Several studies have identified a positive family history of TS and/or ASD in individuals presenting with both disorders concurrently . In a clinical sample of 105 youth with ASD, Canitano et al. observed a positive family history for tic disorders in 59.5 % of youth presenting with ASD and comorbid TS . Burd et al. also identified an association between neuropsychiatric symptoms and a deletion involving exons 4, 5, and 6 of the gene neuroligin 4 in a family study . To further delineate potential genetic associations between TS and ASD, Fernandez et al. examined gene copy number variants in individuals with TS compared to control subjects . While no significant increases in the number of de novo or transmitted rare CNVs were identified in TS subjects compared to controls, gene mapping within rare CNVs in TS subjects showed significant overlap with CNVs previously identified in individuals with ASD . Taken together, these findings reinforce the idea of a common pathogenetic mechanism and shared genetic risk between the two disorders .
Cbln Inhibitory Synaptic Signalling Model
The present study is the first to identify a disease association for any of the CBLNs. Loss of CBLN2 is associated with reduced mediation of inhibitory synaptogenesis that appears in opposition with reduced number of excitatory synapses associated with the downregulation of the LRRTMs and NLGN4X ,, albeit the downregulation/disruption of NRXN1 infers loss of both excitatory and inhibitory synaptic connections. Neural circuits utilise a number of homeostatic mechanisms to regulate the strength of excitation, inhibition and intrinsic excitability thereby maintaining synaptic homeostasis. In most networks, small changes in the balance between excitation and inhibition can have a significant impact on the neuronal firing and there is compelling evidence to suggest that the balance between excitation and inhibition is tightly regulated., When the balance is upset, two distinct mechanisms have been proposed for restoring synaptic homeostasis: one mediated by the strength of excitatory and inhibitory synaptic inputs and the second by the balance of inward and outward voltage-dependent conductances. Thus, the neurons can compensate by using synaptic mechanisms to modify the balance between excitatory and inhibitory inputs or they can use intrinsic mechanisms to modify the balance of inward and outward voltage-dependent current. When there is an imbalance in the excitatory/inhibitory ratio in the neuronal circuits, this could in turn affect neuronal development.
Tourette Syndrome Symptoms Can Look Like Autism Causing Incorrect Diagnosis
THURSDAY, June 22, 2017 — More than one in five children with Tourette syndrome also tests positive for autism, a new study shows.
But it’s unlikely that so many children actually have both disorders. What’s more probable is that Tourette’s symptoms often mimic or seem quite similar to those of autism, the researchers noted.
“Our results suggest that although autism diagnoses were higher in individuals with Tourette’s, some of the increase may be due to autism-like symptoms, especially repetitive behaviors that are more strongly related to obsessive-compulsive disorder,” said study first author Sabrina Darrow, an assistant professor in the department of psychiatry at the University of California, San Francisco.
Tourette’s affects between one and 10 in 1,000 children, according to the U.S. National Institutes of Health. It is more common in males, and typical tics include repetitive throat-clearing, blinking or grimacing.
People with Tourette’s who also had either obsessive-compulsive disorder, or OCD, or attention deficit hyperactivity disorder, or ADHD, were most likely to meet the criteria for autism. For example, 83 percent of those who met the criteria for autism also met the criteria for OCD.
In the general population, autism rates are between 0.3 and 2.9 percent.
The finding supports the idea that the two conditions’ similar symptoms may explain why these youngsters were more likely to test positive for autism, the researchers said.
More information
Read Also: Benefits Of Camel Milk For Autism
Persistent Motor Or Vocal Tic Disorder
While this condition shares some diagnostic criteria with Tourette syndromesuch as onset before the age of 18 and persistence of tics for longer than a yearmultiple motor and/or vocal tics are not diagnostic requirements. A single tic or multiple motor or vocal tics would meet the diagnostic criteria for a Persistent motor or vocal tic disorder.
Persistent motor or vocal tic disorder is a less severe condition than Tourette syndrome. The next tic disorder, often described as the most common and least severe tic condition, is called a transient or provisional tic disorder.
Chronic Motor Tic Disorder
Affecting as many as 1 in 50 people, this disorder is defined by verbal or motor tics that occur for at least one year. This means that an individual will display one or more motor or vocal tics, but not both. As with Tourette syndrome, these tics begin before the age of 18 and occur many times daily, nearly every day or throughout a period that lasts more than a year.
Read Also: How To Tell If My Child Is Autistic
Causes Of Tourette Syndrome
The exact cause of Tourettes is unknown, but it is well established that both genetic and environmental factors are involved. Genetic studies have proved that the overwhelming majority of cases of Tourettes are inherited, although the exact mode of inheritance is not yet known, and no gene has been identified.
Non-genetic, environmental, infectious, or psychosocial factors while not causing Tourettes can influence its severity. Autoimmune processes may affect tic onset and exacerbation in some cases. The unproven and contentious hypothesis that Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections plays a role in the onset of tic disorders and OCD is a current focus of research.
Expanding The Neuropathogenetic Model For Ts
Another gene of interest, ZnT3, is also worthy of mention here if only to demonstrate the utility of the new model to help interrogate broader aspects of TS pathogenicity . ZnT3 is one of the many genes located under the one and only significant linkage peak identified on chromosome 2p23 in the latest TSAICG non-parametric analysis of sib pairs and multi-generation families . In light of our new pathogenic model for TS , ZnT3, a synaptic zinc transporter that controls Zn2+ concentrations within synaptic vesicles, now emerges as a most compelling candidate for TS on 2p23. The concentration of Zn2+ ions within the postsynaptic density , a specialised intracellular region of the excitatory synapse, is known to affect the recruitment of scaffolding proteins like SHANK2 and SHANK3, both of which have been mutated in ASD. The SHANK proteins mediate the attachment of the intracellular PDZ-binding domains of model trans-synaptic receptor/ligand complexes, like NRXN-NLGN and NRXN-LRRTM , to the local actin-based cytoskeleton within dendritic spines. In Purkinje cells, the postsynaptic clustering of SHANK2 with GluD2/GRID2 also appears to be dependent on the integrity of the tripartite NRXN-CBLN1-GRID2 trans-synaptic complex., The LRRNs also have putative extracellular PDZ-binding domains.
Don’t Miss: How To Deal With Aggressive Autistic Child
Common Genetic Link Between Autism And Tourettes Discovered Brain Communication Impaired
This is an MRI scan of the brain. Credit: Lancaster University
Lancaster University researchers have discovered, for the first time, how a genetic alteration that increases the risk of developing Autism and Tourettes impacts on the brain.
Their research also suggests that ketamine, or related drugs, may be a useful treatment for both of these disorders.
Autism affects an estimated 2.8 million people in the UK while Tourettes Syndrome a condition that causes a person to make involuntary sounds and movements called tics -affects an estimated 300,000 people in the UK. The treatments available for both disorders are limited and new treatments are urgently required. Recent research has also shown that these disorders are genetically linked.
People with a genetic deletion known as chromosome 2p16.3 deletion often experience developmental delay and have learning difficulties. They are also around 15 times more likely to develop Autism and 20 times more likely to develop Tourettes Syndrome, but the mechanisms involved are not completely understood.
Using brain imaging studies, neuroscientists have shown that deletion of the gene impacted by 2p16.3 deletion impacts on the function of brain regions involved in both conditions. A key finding is that this genetic deletion disrupts a brain area known as the thalamus, compromising its ability to communicate with other brain areas.
Dr. Dawson urges caution to those who may be thinking of using ketamine therapeutically.
Autism And Tourette Syndrome
Tourette syndrome is an inherited neurological disorder with onset in childhood, characterized by the presence of multiple physical tics and at least one vocal tic these tics characteristically come and go. It is a co-morbid disorder with Autism Spectrum Disorders such as autism and Aspergers syndrome.
Tourettes can occur from the age of 2. Around 30% of people on the spectrum are thought to have Tourettes or Obsessive Compulsive Disorder. This is called a co-morbid disorder. For some, vocal tics are so severe it takes over their communication to the point where it becomes utterly dysfunctional and cause them to lose faith in pursuing communication at all . Movement/motor tics can include jumping, flapping, slapping, biting, blinking, grimacing, hand movements, finger movements, tapping, smelling, squeezing, shrugging, hair flicking, etc and of course compulsive breath holding, coughing, sniffing, and throat clearing. If severe, these tics can take over and interrupt most interaction.
The incidence may be as high as one in a hundred people, up to 530,000 U.S. school-age children may have Tourettes, with the more common tics of eye blinking, coughing, throat clearing, sniffing, and facial movements. People with Tourettes have normal life expectancy and intelligence. The severity of the tics decreases for most children as they pass through adolescence, and extreme Tourettes in adulthood is a rarity. Notable individuals with Tourettes are found in all walks of life.
Don’t Miss: What Does Mild Autism Mean
Common Variants Link Autism Adhd Tourette Syndrome
Laura DattaroOutcome overlap:
Listen to this story:
Genetic variants that contribute to autism may also be involved in attention deficit hyperactivity disorder and Tourette syndrome, according to a new study.
In 2019, researchers from the Psychiatric Genomics Consortium linked variants associated with autism to seven neuropsychiatric conditions, including anorexia, bipolar disorder and schizophrenia. Despite the genetic overlap, though, some of those conditions, such as anorexia and Tourette syndrome, dont tend to co-occur.
The new work homes in on Tourette syndrome a motor and tic condition and three diagnoses that often present with it: More than half of people with Tourette also have obsessive-compulsive disorder or ADHD, and up to 20 percent have autism. Because all four conditions can involve impulsive and compulsive behaviors, some scientists have proposed that they exist along a spectrum, with ADHD on one end, OCD on the other, and autism and Tourette in the middle.
The goal of looking at all the conditions on this spectrum together is to elucidate the genetics underlying their traits, says lead investigator Peristera Paschou, associate professor of biological sciences at Purdue University in West Lafayette, Indiana.
There is a lot of value in zooming out and trying to think across what would be strict diagnostic categories, Paschou says.
Repetitive Behaviors Restricted Interests Occur In Both Disorders Make Correct Diagnosis Tricky Researchers Report
THURSDAY, June 22, 2017 — More than one in five children with Tourette syndrome also tests positive for autism, a new study shows.
But it’s unlikely that so many children actually have both disorders. What’s more probable is that Tourette’s symptoms often mimic or seem quite similar to those of autism, the researchers noted.
“Our results suggest that although autism diagnoses were higher in individuals with Tourette’s, some of the increase may be due to autism-like symptoms, especially repetitive behaviors that are more strongly related to obsessive-compulsive disorder,” said study first author Sabrina Darrow, an assistant professor in the department of psychiatry at the University of California, San Francisco.
Tourette’s affects between one and 10 in 1,000 children, according to the U.S. National Institutes of Health. It is more common in males, and typical tics include repetitive throat-clearing, blinking or grimacing.
People with Tourette’s who also had either obsessive-compulsive disorder or attention deficit hyperactivity disorder were most likely to meet the criteria for autism. For example, 83 percent of those who met the criteria for autism also met the criteria for OCD.
In the general population, autism rates are between 0.3 and 2.9 percent.
The finding supports the idea that the two conditions’ similar symptoms may explain why these youngsters were more likely to test positive for autism, the researchers said.
More information
Read Also: Autism Spectrum High Vs Low
Common Genetic Link Between Autism And Tourettes Impairs Brain Communication
Lancaster University researchers have discovered, for the first time, how a genetic alteration that increases the risk of developing Autism and Tourettes impacts on the brain.
Their research published in the journal Cerebral Cortex also suggests that ketamine, or related drugs, may be a useful treatment for both of these disorders.
Autism affects an estimated 2.8 million people in the UK while Tourette’s Syndrome – a condition that causes a person to make involuntary sounds and movements called tics -affects an estimated 300,000 people in the UK. The treatments available for both disorders are limited and new treatments are urgently required. Recent research has also shown that these disorders are genetically linked.
People with a genetic deletion known as chromosome 2p16.3 deletion often experience developmental delay and have learning difficulties. They are also around 15 times more likely to develop Autism and 20 times more likely to develop Tourettes Syndrome, but the mechanisms involved are not completely understood.
Using brain imaging studies, neuroscientists have shown that deletion of the gene impacted by 2p16.3 deletion impacts on the function of brain regions involved in both conditions. A key finding is that this genetic deletion disrupts a brain area known as the thalamus, compromising its ability to communicate with other brain areas.
Dr Dawson urges caution to those who may be thinking of using ketamine therapeutically.
Initial Case Reports And Case Series
The association between ASD and tic disorders was initially described in single case reports , including several describing the development of tics following withdrawal from long-term neuroleptics . It is unclear, however, whether the neuroleptic medication use produced TS-like symptoms, or inadvertently masked tics that would have already been in existence. These early reports were followed by several case series presenting an elevated concurrence of ASD and TS , as well as examples of tic development positively impacting autistic symptoms in several young children . Collectively, these early reports spurred a growing interest and discussion in regards to the potential genetic overlap between the two disorders.
You May Like: How To Do Pivotal Response Training
Screening For Other Conditions
Although not all those with Tourette’s have comorbid conditions, most presenting for clinical care exhibit symptoms of other conditions along with their tics. ADHD and OCD are the most common, but autism spectrum disorders or anxiety, mood, personality, oppositional defiant, and conduct disorders may also be present. Learning disabilities and sleep disorders may be present higher rates of sleep disturbance and migraine than in the general population are reported. A thorough evaluation for comorbidity is called for when symptoms and impairment warrant, and careful assessment of people with TS includes comprehensive screening for these conditions.
Comorbid conditions such as OCD and ADHD can be more impairing than tics, and cause greater impact on overall functioning. Disruptive behaviors, impaired functioning, or cognitive impairment in individuals with comorbid Tourette’s and ADHD may be accounted for by the ADHD, highlighting the importance of identifying comorbid conditions. Children and adolescents with TS who have learning difficulties are candidates for psychoeducational testing, particularly if the child also has ADHD.
Ketamine May Be Useful Treatment For Tourette’s Syndrome
Ketamine, or related drugs, may be a useful treatment for Autism and Tourettes, Lancaster University researchers report. The also found for the first time, how a genetic alteration that increases the risk of developing both these disorders impacts on the brain.
Autism affects an estimated 2.8 million people in the UK while Tourettes Syndrome a condition that causes a person to make involuntary sounds and movements called tics – affects an estimated 300,000 people in the UK. The treatments available for both disorders are limited and new treatments are urgently required.
Recent research has also shown that these disorders are genetically linked.
People with a genetic deletion known as chromosome 2p16.3 deletion often experience developmental delay and have learning difficulties. They are also around 15 times more likely to develop Autism and 20 times more likely to develop Tourettes Syndrome, but the mechanisms involved are not completely understood.
Read Also: Teach Baby Body Parts
How They Are Different
Tics from Tourette’s syndrome are different from the movements or noises that kids with ADHD might make. They almost always involve fast, repeated face or shoulder movements or sounds, which happen the same way each time.
Often, kids with ADHD won’t have any tic-like movements. Instead, they have trouble staying focused or paying attention. They might be easily distracted or have problems staying organized.
Children with Tourette’s syndrome often outgrow their tics by their late teens or early adult years — they happen less often and sometimes disappear altogether. ADHD symptoms often last into adulthood.
Also, Tourette’s syndrome is rare. The CDC found that about 138,000 kids in the U.S. have been diagnosed with it, while about 6.4 million have ever been diagnosed with ADHD.
Researchers believe that genetics have a lot to do with both conditions. But other possible causes of ADHD might include brain injury, low birth weight, or smoking and drinking during pregnancy.
Lrrtms Compete For Neural Circuitry
Phenotypic variability can also be affected by non-genetic factors, or second hits such as prematurity, perinatal trauma, injury, hypoxia, oxidative stress, infections, inflammations and autoimmunity, neural and psychosocial stressors or other modulators including gender. It has been shown that there are sex-specific differences in the topographic segregation and functionality of GABA-A systems in the substantia nigra and that the presence of circulating testosterone is essential for the development of the substantia nigra region in the neonatal period and to a lesser extent in the final maturation in the peripubertal period. In this regard, the role for testosterone in the extreme male brain hypothesis has been suggested in ASD. Similarly, OCD has been proposed as an alternative phenotypic expression of the TS genes with a gender-dependent difference in the expression leading to male members of the family exhibiting more tic behaviours and the female members exhibiting OCD., An imbalance in the excitatory/inhibitory ratio in local and extended neuronal circuits could therefore have a role.
Recommended Reading: Average Life Expectancy Autism