Causes of Autism

What are the causes of Autism?


Parents of children with autism usually ask the following questions when they visit a developmental pediatrician, neurologist, psychiatrist or a psychologist:


• How did our child develop autism?

• My child was hale and healthy and had even started to speak a few words. Then, what happened suddenly?

• So, is autism acquired?

• Is it genetic? Has it come from "us", the parents?


Do we yet have clear cut answers for these questions? Some yes and some no!! Let us explore what is known and what is still being understood. For a fact, the understanding of the "what”, "why" and "how" of autism is still incomplete.


Genetics: Though autism's genetic factors explain most of the risk of developing autism, they do not explain all of it. A common hypothesis is that autism is caused by the interaction of a genetic predisposition and an early environmental insult. Several theories based on environmental factors have been proposed to address the remaining risk. Some of these theories focus on prenatal environmental factors, such as agents that cause birth defects, and others focus on the environment after birth, such as children's diets.


Prenatal environment: The risk of autism is associated with several prenatal risk factors, including advanced age of parents, diabetes, bleeding, and use of psychiatric drugs in the mother during pregnancy. Autism has been linked to birth defect agents acting during the first eight weeks from conception (rare).


Perinatal environment: Autism is associated with some perinatal and obstetric conditions. A 2007 review of risk factors found associated obstetric conditions that included low birth weight and gestation duration, and hypoxia during childbirth. This association does not demonstrate a causal relationship. As a result, an underlying cause could explain both autism and these associated conditions. A 2007 study of premature infant showed that those who survived a cerebellar hemorrhagic injury (bleeding in the brain that injures the cerebellum) were significantly more likely to show symptoms of autism than controls without the injury.


Postnatal environment: A wide variety of postnatal contributors to autism have been proposed, including gastrointestinal or immune system abnormalities, allergies, and exposure of children to drugs, vaccines, infection, certain foods, or heavy metals. The evidence for these risk factors is anecdotal and has not been confirmed by reliable studies. The subject remains controversial and extensive further searches for environmental factors are underway.


Mercury: Mercury poisoning has been thought to be one of the causes of autism. The sources of mercury are fish, inorganic substances, cosmetics and vaccines. This cause has not been very well validated, since the features of mercury poisoning and autism do not match and evidences so far are indirect.


Lead: Lead poisoning has been suggested as a possible risk factor for autism, as the lead blood levels of autistic children has been reported to be significantly higher than typical. The atypical eating behaviors of autistic children, along with habitual mouthing and pica, make it hard to determine whether increased lead levels are a cause or a consequence of autism.


MMR vaccine: Though, as a parent, it is important for you to get to the root of the problem, the motive should not be to blame or attribute the reason or guilt on anybody's shoulders or any particular factor. The cause if at all, we feel, needs to be explored only for an understanding and the possibility of finding a way to correct or prevent it.


Signs and Symptoms of Autism


What are the Signs and Symptoms of Autism?


Social Skills Difficulty:

The social issues (problems in interacting, forming and maintaining relationships) children with autism face lead to serious problems in their everyday lives. For example, by his first birthday a toddler interacts with others by looking at people in the eye, copying words or actions of others, using simple gestures like clapping or waving, etc. But toddlers with autism have delayed milestones and they have a difficult time learning to interact with others and their environment. As these children grow up, they show a lack of interest in interacting with other people, which in turn leads to social isolation and other children not wanting to play with them.


Examples of Social Issues related to Autism:

• Poor eye contact

• Does not respond to his name

• Prefers to stay alone

• Shows inappropriate expressions

• Does not understand non-verbal cues of others

• Has difficulty in understanding or expressing his/her own feelings

• Avoids touch or seeks more physical touch for example hugging, kissing, etc.


Communication Skills Difficulty:

Each child with autism spectrum disorder differs in communication skills from the others. Some of them can speak well, whereas others may be mute, still some others would have speech in the form of one or two words. About 25 to 30% of children with autism speak a few words at 12 to 18 months of age after which, they may be lost. Most of these children have a history of language developmental delay.


Examples of difficulty in communication skills are:

• Delayed development of speech and language skills

• Repetitive words or sentences over and over again (echolalia)

• Irrelevant speech i.e. gives unrelated answers to questions

• Does not point or respond to pointing


Unusual interests and behavioral issues:

Individuals with autism often have unusual interests and behaviors.

• Plays with toys in an unusual manner

• Obsession with irrelevant objects like bottle caps, wires, buttons, key rings, water pipes, etc.

• Lines up objects or toys

• Minor changes in the routine or environment can be very upsetting

• Repetitive behaviors like hand flapping, rocking, spinning objects

• Smelling objects or people

• Strong avoidance of certain food items, tastes, textures of clothing, etc.

• Unusual fears or dislikes, e.g. cutting nails, flowers

• Self stimulatory behaviors like rocking, tapping hands/ feet


Physical Problems:

While social and behavioral issues are more obvious it these children, some characteristic physical features may also be noticed. These may also add to their difficulties in interacting with their environment.


Examples of physical problems in children with Autism:

• Abnormal tone of muscle (too tight or too loose muscles)

• Poor proximal muscle strength (i.e. of shoulders and hip muscles)

• Flat Feet

• Poor eye-hand coordination

• Limb apraxia, (difficulty in performing planned movements of the arms or legs)

• Balance problems

• Abnormal reaction to sensory stimuli


Other symptoms:

• Increased hyperactivity

•  Impulsive behavior, for e.g. acting without thinking

• Short attention span, gets distracted very easily

• Self - injurious behavior like head banging, biting oneself, etc.

• Aggressive behavior towards others like biting, scratching, pulling others hair, throwing objects, etc.

• Throwing temper tantrums

• Odd sleep and food habits, for example; may have disturbed sleep or may not eat food items which are white in color, etc.



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