Autism Spectrum Disorder: An Overview

Healthful Vitality | 04/12/2019 | By Dr Subarna Ghosh | Autism Spectrum Disorder: An Overview

Autism spectrum disorder (ASD) is a neuro-developmental (brain development) disorder that adversely affects a person’s social, behavioral, and communicative functions. Autistic individuals face difficulties in social interaction, demonstrate repetitive behavioral patterns, and have limited interests. Autism is a ‘spectrum’ disorder because the symptoms observed in this condition exhibit wide variation in terms of their type and severity. Depending on the variations in the presenting clinical manifestations, ASD is divided into sub-groups such as, autistic disorder, Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS), and Asperger syndrome.  

In most cases, ASD develops in children aged 3 to 8 years. Only in regressive sub-types of the condition, ASD symptoms can manifest in an individual later in life. In recent years, there has been a significant rise in the prevalence of ASD. Worldwide, the estimated incidence rate of ASD is believed to be about 90 to 250 per 10,000 individuals. As per CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network about 1 in 59 children are diagnosed with ASD. ASD is four times more commonly seen in boys than girls. The disorder is reported to occur in all ethnic and socio-economic groups.

Risk Factors of Autism Spectrum Disorder

The development of ASD is believed to be multi-factorial in origin. Genetic, environmental, and nutritional factors are thought to play a role in the development of the disorder. The main risk factors for ASD include the following:

• Genetic predisposition is a key risk factor in the development of ASD. Mutations, deletions, and duplication of genes that are involved in intellectual development of an individual are found in ASD
• Family history of ASD increases the risk of the condition. This is especially true for siblings (2% to 18% greater risk) and identical twins (36% to 95% risk)
• The risk of ASD is higher in individuals with certain genetic and chromosomal abnormalities such as, tuberous sclerosis, fragile X syndrome, and Down syndrome
• Intake of prescription drugs such as thalidomide and valproic acid during pregnancy have been linked to higher risk of ASD in the offspring
• Recent research indicates a strong association between vitamin D deficiency (fetal and early childhood) and development of ASD
• The risk of ASD is higher in low birth weight infants
• Pregnant women over the age of 35 years are at increased risk of giving birth to babies with ASD

Signs and Symptoms of Autism Spectrum Disorder

Most times, the signs and symptoms of ASD emerge in early childhood and last for the rest of the person’s life. The chief signs and symptoms noted in children with ASD are as follows:

• Difficulty in understanding and expressing emotions
• Difficulty in understanding mood of other individuals
• Impaired expressive language
• Abnormality in making eye contact
• Difficulty to cope with changes in daily routine
• Prefer playing alone with restricted use of toys

Signs and Symptoms Associated with Social Interaction

• When called by their name, autistic children may fail to respond immediately
• Prefer to be alone most times and resist display of affection such as cuddling
• Lack facial expression
• Delayed speech
• Difficulty in starting a conversation
• Speak with an odd tone or rhythm, for example- sing-song voice
• Repeats words, verbs, and phrases
• Difficulty in understanding simple questions
• During social interaction, children with ASD can be passive or even aggressive
• Difficulty in understanding non-verbal cues

Signs and Symptoms Associated with Behavioral Patterns

• Repetitive movements, for example- rocking back and forth, hand flapping, spinning, etc.
• Perform activities that can injure oneself such as, head-banging
• Develop specific daily routines
• Co-ordination problems such as stiff body language, clumsiness, etc.
• Are interested in simple objects like spinning wheels, although can fail to understand the overall function of such objects?
• Increased sensitivity to light, sound, and touch. May remain indifferent to temperature changes or pain
• Can fixate on an object with abnormal intensity?
• Have specific food preferences, especially in terms of food texture?

The signs and symptoms of ASD may improve as the child grows. Furthermore, adults with ASD may demonstrate fewer disturbances in behavioral patterns and better skills at social interaction. Additionally, children who show mild autistic-traits may eventually lead normal lives as they grow older. However, for some autistic individuals, behavioral, social, and communicative issues may worsen with age.

Diagnosis for Autism Spectrum Disorder

The diagnosis of ASD is primarily made through the signs and symptoms of the child. The diagnostic evaluation involves ‘Developmental, Dimensional, and Diagnostic’ interview (answered by parents and caregivers) and direct observation of the child by a healthcare professional. There is no laboratory test (blood or biomarker test) or imaging test that can detect the condition. Usually, ASD is diagnosed in children older than 3 years. However, some children can start developing signs of ASD much sooner (<18 months).

Treatment

At present, there is no cure for ASD. At the same time, there are limited treatment options to ameliorate the signs and symptoms seen in ASD. Different psychosocial interventions have been developed that target both the main symptoms and the associated symptoms of ASD. Applied behavior analysis (ABA) is a treatment method which is based on theories of learning and operant conditioning. The treatment involves specific intervention targets, along with positive reinforcement (verbal praise, edible rewards, tokens, etc.), with repetition of learning-trials which is a key component.

Another intervention that is effective in treating the chief symptoms of ASD is Pivotal Response Treatment (PRT). Indeed, this treatment method involves a more naturalistic behavioral method. Notably, PRT targets specific skills, along with, the motivations (i.e. pivotal areas) of the patient. Compared to ABA therapies, PRT is less time-intensive. These interventions should be started in early childhood for good prognosis. Before taking any medications or treatment, you should consult your physician.

Complications of Autism Spectrum Disorder

A number of medical complications are seen in individuals with ASD. These include the following:

• Epilepsy: Observed in 20% to 30% of the patients
• Intellectual disability: Observed in about 50% of the patients
• Uneven cognitive profile: Cognitive strengths and weaknesses evident on cognitive testing
• Mental health issues such as anxiety
• Sleep disturbances

Complications associated with impaired social interaction and behavioral patterns include the following:

• Social isolation
• Problems encountered at school, learning difficulties
• Employment problems

(Also Read: Non-Communicable Diseases Among the Biggest Threats to Global Health Progress).

References:

1. Mazahery H, Camargo CA, Conlon C, Beck KL, Kruger MC, von Hurst PR. Vitamin D and Autism Spectrum Disorder: A Literature Review. Nutrients. 2016;8(4):236. Published 2016 Apr 21. doi:10.3390/nu8040236 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4848704/
2. Masi A, DeMayo MM, Glozier N, Guastella AJ. An Overview of Autism Spectrum Disorder, Heterogeneity and Treatment Options. Neurosci Bull. 2017;33(2):183–193. doi:10.1007/s12264-017-0100-y https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5360849/
3. DeFilippis M, Wagner KD. Treatment of Autism Spectrum Disorder in Children and Adolescents. Psychopharmacol Bull. 2016;46(2):18–41 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5044466/
4. British Medical Bulletin- Autism Spectrum Disorder https://academic.oup.com/bmb/article/127/1/91/5073298
5. Center for Disease Control and Prevention (CDC) Fact Sheet: Autism Spectrum Disorder.