Classical autism is part of the autism spectrum disorder, which also includes Aspergers syndrome and pervasive developmental disorder (PDD). The 3 major characteristics of this neuro-developmental disorder are: impairment in social skills, communication, and repetitive behaviours. Autism has a very broad phenotype and severity of symptoms can vary between individuals. Typical symptoms include: language delay, oversensitivity to sights, sounds, and textures, typical or below average IQ, and an inability to understand social cues. Over the past few years, the prevalence of autism has increased dramatically. Children with classical autism can be diagnosed between the ages of 1.5-3 years old. Diagnosis requires an extensive screening test by doctors, psychologists, neurologists and more[1]. Due to the broad genotype of autism, there is no single, conclusive cause for the disorder. However, many theories have been proposed including the CNV theory, serotonin dysregulation theory, SHANK-3 mutation theory, intense world theory and the immune dysregulation theory. Although the etiology of autism is still unclear, a number of potential treatments including hyperbaric oxygen therapy, educational interventions and reality treatments with animals have been successful[2].

1. Autism Fact Sheet: National Institute of Neurological Disorders and Stroke (NINDS). (n.d.). National Institute of Neurological Disorders and Stroke (NINDS). Retrieved February 8, 2013, from
2. Cai, Y. et al. Design and Development of a Virtual Dolphinarium for Children with Autism. Neural Systems and Rehabilitating Engineering. 42; 35-40 (2013).

Autism Treatments

main article: Autism Treatments
author: Steven Wojnarski
Autism is one of the most studied, yet unfortunately most misunderstood disorders of the mind, possibly because it encompasses such a wide variety of disabilities and symptoms. Fortunately, treatment research for ASD is one of the most cutting edge topics in neurobiology today. No cure has yet been discovered, but science is coming close, and has already made strides in either managing or in some cases eliminating some of the behaviors often associated with ASD such as aggression and hyperactivity [1]. Currently, treatments for autism spectrum disorders include hyperbaric oxygen therapy, education interventions, pharmaceutical treatments, and virtual reality treatments- these are some of the most cutting edge branches of science being studied today. Furthermore, there exists a slight gender bias in that young males are often studied much more than their female counterparts.

1. Bent, S. et al. Hyperbaric Oxygen Therapy in Children with Autism Spectrum Disorder. Journal of Autism and Developmental Disorders. 42; 1127-1132 (2012).
2. second full source reference

Copy Number Variations

main article: Copy Number Variations
author: Stephanie Rizzetto

Copy Number Variants
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Duplications or deletions of genes on chromosomes

Autism spectrum disorder (ASD) is a neuro-developmental disorder that is characterised by three main impairments, social skills, communication, and repetitive behaviours [1]. There is great range in the intensity and symptoms of ASD and thus there is no exclusive cause that has been determined [1]. However, deletions and duplications in sections of chromosomes, called copy number variants (CNVs), have demonstrated promising correlations to the causation of ASD [3]. The following CNVs, CAPS2, PTCHD1, and NRXN1, have been proposed to have effects on synaptic adhesion proteins, the release of brain-derived neurotrophic factor, and cerebellar deficits among others [1] [2] [3].

1. Noor, A., Whibley, A., Marshall, C., Gianakopoulos, P., Piton, A., Carson, A., et al. (2010). Disruption at the PTCHD1 locus on Xp22.11 in autism spectrum disorder and intellectual disability. Science Translational Medicine, 2(49), 1-16. Retrieved March 4, 2013, from the Pubmed database.
2. Sadakata, T., Kakegawa, W., Mizoguchi, A., Washida, M., Katoh-Semba, R., Shutoh, F., et al. (2007). Impaired cerebellar development and function in mice lacking CAPS2, a protein involved in neurotrophin release. The Journal of Neuroscience,27(10), 2472-2482. Retrieved March 4, 2013, from the Pubmed database
3. Schaaf, C., Boone, P., Sampath, S., Williams, C., Bader, P., Mueller, J., et al. (2012). Phenotypic spectrum and genotype-phenotype correlations of NRXN1 exon deletions. European Journal of Human Genetics, 20, 1240-1247. Retrieved March 4, 2013, from the Pubmed database.

Immune Responses in Autism

main article: Immune Responses in Autism
author: Lama Al Bachir

Extensive Microglial Activation
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Extensive chronic microglial activation (bottom) relative to a control group (top).
Suzuki K. et al. JAMA Psychiatry (2013)

Autism Spectrum Disorder is a multifactorial physical disorder making the abnormal behaviour associated with it different from typical frustration or tantrums. Individuals with the disease suffer from a widespread range of symptoms from sensory overload to gastrointestinal symptoms making every day life a challenge.

Prenatal and postnatal infections have each been hypothesized to lead to immune dysregulation occurring at critical time frames in development. This phenomenon has linked chronic inflammation (and neuroinflammation) with the behavioral abnormalities observed in those diagnosed with autism. Autistic children have shown increased levels in numerous growth factors and cytokines which are crucial for cell proliferation, differentiation and cell survival [1]. Anatomically; extensive microglial activation has been observed in the cerebellum as well as cortical areas of the brain[2].

Recent research regarding immune responses in autism has shifted the focus from being strictly neurological and to incorporate neuroimmunology discussing the gut and its secondary neurological effects[3]. While the relationships between immunology and the neurodevelopmental aspects of ASD show promising insight into the disorder – whether or not it is a cause or a corresponding effect of autism remains to be investigated.

1. Ashwood, P., Enstrom, A., Krakowiak, P., Hertz-Picciotto, I., Hansen, R. L., Croen, L. A., Ozonoff, S., & Pessa, I. N. (2008). Decreased transforming growth factor beta1 in autism: A potential link between immune dysregulation and impairment in clinical behavioral outcomes.Journal of Neuroimmunology, 204, 149-153.
2. Vargas, D. L., Nascimbene, C., Krishan, C., Zimmerman, A. W., & Pardo, C. A. (2005). Neuroglial activation and neuroinflammation in the brain of patients with autism. Annals of Neurology, 57(1), 67-81.
3. Frye, R.E., Melnyk, S., MacFabe, D.F. (2013) Unique acyl-carnitine profiles are potential biomarkers for acquired mitochondrial disease in autism spectrum disorder. Translational Psychiatry, 3(1)

Serotonin Theory of Autism

main article: Serotonin Theory of Autism
author: Ailya Jessa

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Structure of the Monoamine Neurotransmitter Serotonin
(Retrieved on March 16, 2013)

Serotonin is a monoamine neurotransmitter that has long been implicated in the etiology of Autism. Serotonin was originally identified as playing a role in Autism in the 1960s when a study found that a significant number of Autistic individuals had increased levels of blood platelet serotonin [1]. Subsequent studies have found that changes in serotonin levels during development can affect white and grey matter density and overall brain morphology. Research also suggests that there may be an asymmetry in serotonin synthesis in the brain, which has been associated with deficiencies in language and communication (which are two of the core symptoms of Autism) [2]. A number of serotonin transporter gene polymorphisms have also been associated with Autism however, there is not a single gene variant responsible for Autism [3]. Most studies in past have implicated excess serotonin in the aberrant development in Autism in both the brain and the periphery. However, newer studies also suggest that serotonin depletion during development also produces a similar phenotype [3]. The role of serotonin in Autism still remains unclear possibly due to the heterogeneity of the disorder. The prevalence of Autism increases every year, so identifying the role of serotonin in Autism may help us understand the causes and potentially help us develop treatments for this complex disorder.

1. Schain, R., & Freedman, D. (1961). Studies on 5-bydroxyindole metabolism in autistic and other mentally retarded children. The Journal of Pediatrics, 58 (3), 315-320.
2. Chandana, S. R., Behen, M. E., Juhasz, C., Muzik, O., Rothermel, R. D., Mangner, T. J., et al. (2005). Significance of abnormalities in developmental trajectory and asymmetry of cortical serotonin synthesis in autism. Journal of Developmental Neuroscience, 23, 171– 182.
3. Kane M., Angoa-Perez M., Briggs D., Sykes C., Francescutti D., Rosenburg D. & Kuhn D.(2012). Mice Genetically Depleted of Brain Serotonin Display Social Impairments, Communication Deficits and Repetitive Behaviors: Possible Relevance to Autism. PLOS ONE, 7(11), 1-14.

Shank3- postsynaptic protein involvement in Autism

main article: Shank3- postsynaptic protein involvement in Autism
author: Beza Mahano

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Shank3 synapse

Shank3 is a scaffolding protein involved in neuronal connections, formation and maturation of dendritic spines. Shank3 postsynaptic protein with the associated glutamate receptors function together to form spines and functional synapses [1] [2]. It's mutation has been implicated in neurobehavioral symptoms in autistic individuals. Some of the evidence showing that shank3 mutation can be identified in autistic individuals is provided by mice models, a disruption of shank3 in generated knockout mice shows causality between a disruption in the shank3 gene and the genesis of autistic-like behaviours [2]. Both structural and functional neuroimaging have shown alerted neuronal connectivity in various brain areas; for instance, in areas that function to accomplish language problems, such as the left inferior frontal gyrus and temporal gyrus. It is believed that understanding the molecular dynamics of shank3 translates into targeted pharmacological treatments for shank3 mutation and thus treatment of autism [2]. Presently studies that have dealt with molecular intervention in knockout mice have been successful in reversing some autistic symptoms.

1. Durand, C M.; Perroy, L.; Loll, F.; Perrais, D.; Fagni, L.; et al. Shank3 mutations identified in autism lead to modification of dendritic spine morphology via actin-dependent mechanism. Molecular Psychiatry. 17; 71-84 (2011).
2. Peca, J.; Feliciano, C.; Ting, J.T.; Wang, W.; Wells, M.F.; et al. Shank3 mutant mice display autistic-like behaviors and striatal dysfunction. Nature. 427: 437-442 (2011).

The Intense World Theory

main article: The Intense World Theory
author: Jin A Jung
Classical Autism is part of the autism spectrum disorder with 3 major characteristics: impairment in social skills, communication, and repetitive behaviours. Since the autistic genotype is very broad and varied, no single, determined cause is found for the disorder. Among many theories that have been proposed to explain autism, the intense world theory is a unifying theory with suggestion of hyper-function of local neural pathways. It characterizes autism with hyper-attention, hyper-memory, hyper-perception, as well as hyper-emotionality. Enhanced neural-plasticity, neural micro-circuits, and VPA mice models are used to support the intense world theory[1]. It suggests that classical autism enhances neuronal reactivity across the amygdala and neocortex, thereby amplifying fear processing and memories.

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