What are Autism Spectrum Disorders (ASD)?

Autism Spectrum Disorders are a group of incurable developmental disabilities that affect the brain processes.

The symptoms of Autism Spectrum Disorders generally include1:

  • Impairments in social and communication skills
  • Repetitive patterns of behavior

Because of the complex nature of the disorder, children with various developmental delays should undergo diagnostic screening before 3 years of age. Indeed, the earlier the diagnosis, the better the benefits of behavioral interventions2.

The prevalence of Autism Spectrum Disorders has increased over time from 1 in 150 children in the year 2000 to 1 in 68 children in 20143. This large increase is related to increased knowledge of the disease, greater access to specialized health services and related treatments, and finally to the standardization of diagnosis – using the well-established Diagnostic and Statistical Manual of Mental Disorders (DSM)5.

There are almost 5 times as many boys diagnosed with Autism Spectrum Disorders as girls, with an estimated prevalence of 23,6 per 1,000 in boys aged 8 vs. 5,3 per 1,000 in girls aged 84.

 

Sources:

  1. Centers for Disease Control and Prevention (CDC). Autism and Developmental Disabilities Monitoring Network – 2012. https://www.cdc.gov/ncbddd/autism/documents/addm-2012-community-report.pdf. Last visited October 2018
  2. Centers for Disease Control and Prevention (CDC). Basics about ASD. https://www.cdc.gov/ncbddd/autism/facts.html. Last visited October 2018
  3. Centers for Disease Control and Prevention (CDC). Community Report on Autism – 2016. https://www.cdc.gov/ncbddd/autism/documents/comm-report-autism-full-report.pdf. Last visited October 2018
  4. Centers for Disease Control and Prevention (CDC). Morbidity and Mortality Weekly report. https://www.cdc.gov/mmwr/volumes/65/ss/ss6503a1.htm. Last visited October 2018
  5. Diagnostic and Statistical Manual of Mental Disorders, 5th edition.  https://doi.org/10.1176/appi.books.9780890425596. Last visited October 2018

Etiology of Autism Spectrum Disorders and focus on genetic risk factor

The etiology of Autism Spectrum Disorders is multifactorial: there may be many different genetic and environmental risk factors for developing the disorder1.

It is widely accepted that genetic variation plays a role in the development of Autism Spectrum Disorders: “….It’s a highly genetic disorder because we have more genetic issues coming from that population, per se” US KOL, November 20132.

With recent advances in genomic sequencing technologies, substantial progress has been made in identifying ASD-associated genes3,4. Genomic analysis has identified numerous candidate genes with hundreds of implicated loci5,6; many of these same genes / loci have been identified in analyses of other similar disorders, such as attention deficit hyperactivity disorder (ADHD), epilepsy, and schizophrenia. The evidence clearly shows that Autism Spectrum Disorder is not a single-gene disorder but is instead a highly complex heterogeneous disorder involving multiple genes with many simultaneous genetic variations, and that there is a complex interplay between genetic, epigenetic, and environmental factors7,8,9.

Sources:

  1. Chaste P and Leboyer M. Dialogues Clin Neurosci. 2012. 14(3):281-292
  2. GlobalData: Opportunity Analyzer Autism Spectrum Disorders. March 2014
  3. Matsunami N, et al. PloS ONE 8(1):e52239. 2013
  4. Pinto D, et al. Nature. 2011. 466(7304):368-372
  5. Betancur C. Brain Res. 2011. 1380:42-77
  6. Marshall CR and Scherer SW. Methods Mol Biol. 2012. 838:115-135
  7. Eapen V. Curr Opin Psychiatry. 2011. 24(3):226-236
  8. El-Fishawy P and State MW. Psychiatr Clin of North Am. 2010. 33(1):83-105
  9. Johnson CP and Myers SM. Pediatrics. 2007. 120(5):1183-1215

Diagnosis

Currently, there is no blood test or brain scan which can diagnose Autism Spectrum Disorders.

Instead, Autism Spectrum Disorders is diagnosed by qualified professionals who conduct comprehensive psychological and behavioral evaluations. These evaluations can include clinical observation, parental reports of developmental and health histories, psychological testing, speech and language assessments, and / or the use of one or more questionnaires developed specifically for people with Autism Spectrum Disorders. Moreover, neurologic and genetic testing can be used to rule out other disorders1.

By age two, a diagnosis of Autism Spectrum Disorders by an experienced professional can be considered reliable, although Autism Spectrum Disorders can sometimes be detected at 18 months. However, many children do not receive a final diagnosis until much older2. “For diagnostics criteria, patients should have persistent deficits in social communication and social interaction across multiple contexts, and restricted, repetitive patterns of behavior, interests or activities. Those symptoms must be present in the early developmental period and cause clinically significant impairment in social, occupational, or other important areas of current functioning”3. To ensure a specific diagnosis, observed symptoms should not be related to another disability, such as mental retardation or other developmental disorders.

 

Sources:

  1. Centers for Disease Control and Prevention (CDC). Autism and Developmental Disabilities Monitoring Network – 2012. https://www.cdc.gov/ncbddd/autism/documents/addm-2012-community-report.pdf. Last visited October 2018
  2. Centers for Disease Control and Prevention (CDC). Screening and Diagnosis. https://www.cdc.gov/ncbddd/autism/screening.html. Last visited October 2018
  3. Autism Speaks. DSM-5 Criteria. https://www.autismspeaks.org/what-autism/diagnosis/dsm-5-diagnostic-criteria. Last visited October 2018

Linking Autism Spectrum Disorders with the metabolism approach

The fundamental molecular pathways involved in Autism Spectrum Disorders are still largely uncharacterized, but current research implicates dysregulation in neurotransmitter metabolism, as well as alteration in information processing, and / or deficiencies in growth regulation and protein synthesis1,2.

MedDay seeks to further understand the metabolic abnormalities in Autism Spectrum Disorders and to examine direct metabolic-based interventions to improve patient outcomes.

 

Sources:

  1. Chen JA, et al. Annu Rev Pathol. 2015. 10:111-144
  2. Muller CL, et al. Neuroscience. 2016. 321:24-41