The underlying cause of Autism spectrum disorder remains unknown for almost 90 percent of the cases and is therefore yet a matter of research.
Autism spectrum disorder is marked by impaired social interactions, communication disorders and repetitive behavior.
The latest statistics show that little over 1 percent children suffer from Autism with male to female ratio of 5:1.
The number of autistic children is on the rise through out the world. This is probably due to increase in premature births and the remarkably improved survival rate of even extreme prematures.
Autism spectrum disorders are known to have a strong genetic predisposition and disturbed immune system, which gets emphasized by the environmental factors.
In 2008, a retrospective study, carried out by Dr.Catherine Limperopoulos and colleagues from McGill University and Harvard Medical School, showed the high incidence of Autism spectrum disorders (26%) in prematurely born babies with birth weight of 1500 grams or less.
Expression of Autism varies with gestational age at birth
The news sited in Science Daily on 03 April 2012 says that the symptoms of Autism were found to be much more severe in babies born prior to 37 weeks or after 42 weeks of gestation according to new research out of Michigan State University which is carried out by Tammy Movsas, (a postdoctoral epidemiology fellow at Michigan State University's College of Human Medicine).
In a university news release, Tammy Movsas said, "With preterm and post-term babies, there is something underlying that is altering the genetic expression of autism.
The outside environment in which a preterm baby continues to mature is very different than the environment that the baby would have experienced in utero. This change in environment may be part of the reason why there is a difference in autistic severity in this set of infants.
Whereas, for post-term babies, the longer exposure to hormones while a baby is in utero, the higher chance of placental malfunction and the increased rate of C-section and instrument-assisted births may play a role."
Disturbed Immune System
Another study that was published in the April 2012 issue of International Journal of Developmental Neuroscience supported that disturbed immune system in children with classic autism may be related to genetic factors that predispose a child to Autism spectrum disorders.
Merlin G. Butler, professor of psychiatry at the KU Medical Center, said, “The importance of identifying early immunological disturbances that may contribute to autism has implications for identifying risk factors, diagnosis and possibly intervention as cytokines may play a role in the function of the developing brain,"
The earlier study on the subject was conducted by Johns Hopkins Children's Center investigators and published in the February 2008 issue of the Journal of Neuroimmunology. In this study the researchers had suggested that the mother's immune system may be yet another factor or a trigger in those already predisposed to Autism spectrum disorders.
Unusual antibody levels were recorded in some autistic children. These autistic children neither showed any evidence of infection nor any clinical evidence of autoimmune disorder. This was thought provoking.
Researchers started tracking down the source of antibodies in these autistic young infants. Could the antibodies be transferred from the mother to the fetus through the placenta and could these antibodies directly affect the fetal brain development?????
The control study that followed showed that 40 percent of the samples obtained from the mothers of autistic children showed significantly stronger reactivity between antibodies and brain proteins. Further, the presence of maternal antibodies was associated with developmental regression and increasingly immature behaviour in children that are a hallmark of autism.
However, further studies are needed to confirm the role of maternal antibodies in fetal brain injury.
For early diagnosis of Autism spectrum disorder-
In an infant of 6-12 months of age watch for -
1. Impaired social interactions
• Poor eye to eye contact
• Rarely smiles- even at the caregiver
• Does not react to stranger
• Rarely imitates the sounds and movements
• Never laughs
• Self engrossed – does not seek for attention.
• Does not reach up when reached to be picked up.
2. Communication disorders
• Infrequent babbling
• Does not respond to his/her name with increasing consistency
• Does not gesture to communicate by 10 months
4. Unusual body movements – for example - frequently stiffens limbs, rotates hands and/or attains unusual postures.
5. Repetitive behavior
6. Delay in achieving motor milestones.
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