In the last year I have been asked questions about autism at an increasing frequency by parents, grandparents, aunts, uncles, and siblings who are troubled by the confusing presentation of their developmentally disabled relative. This has accompanied an increasing social awareness of autism by families seeking more research funding and insurance coverage. There has been an influx of researchers from many disciplines seeking to contribute to the research effort by the community of scholars that has been created during the last five or six years. This blog is meant to provide some basic information about this spectrum disorder.
Autism was first recognized as a separate disorder in the early 1940s when two researchers, Leo Kanner and Hans Asperger, working independently in different countries, described several individuals and gave them the name "autism" after the term used by Eugene Bleuler in describing the social isolation found in schizophrenia. They described an intense aloneness, a boy a bubble, and an insistence on sameness or repetition, blended with some areas of satisfactory functioning. Prior to their papers, these children were classified as mild to severe intellectual disability, or seizure disorder patients, or language disabled patients. Undoubtedly the syndrome was not obvious because it is a spectrum and blends with "normality" at one end and severe disability at the other.
The Modified Checklist for Autism in Toddlers (M-CHAT) is designed for use in children up to 18 months but can be used up to 36 months if there are developmental delays and up to 60 months if the child demonstrates impaired social skills. While there are 23 questions in the checklist, 6 can be used as a quick screen. If there are two negatives, then the child should be referred for a detailed evaluation and diagnosis. Remember, these questions are just a screen.
1) Does your child take an interest in other children?
2) Does your child ever use his/her index finger to point, to indicate interest in something?
3) Does your child ever bring objects over to you to show you something?
4) Does your child imitate you? If you were to make a face, would your child imitate it?
5) Does your child respond to his/her name when you call?
6) If you were to point to a toy across the room, does your child look at it?
Autism is diagnosed by abnormal social interactions, compromised communication and repetitive behaviors. This neurodevelopmental disorder has a genetic underpinning. Concordance in identical twins is greater than 90% but less that 10% in fraternal twins or siblings. The genetics have become more complicated recently due to new genetic discoveries. In the past genetic research was focused on single neucleotide polymorphisms (SNPs) in which a single base is substituted in a DNA sequence. However, recently other genetic abnormalities have been discovered in which extra copies of genes are present, e.g., three copies rather than two (copy number variations, CNV) or even long sections duplicated. In addition, spontaneous mutations have been found to be much more common that previously thought. So the child could have the mutation but it is not found in the parents' somatic cells but only in the parental cells that unite to make an offspring. This could account for 25% of all cases. There could be hundreds of loci that convey risk.
These genes encode the proteins that shape and determine the function, stability, and plasticity of the neurons and the connections between neurons called synapses. Neurons form circuits and the circuits and neurons can be either stimulative or inhibitory. The current theory is that there is an imbalance in these two activities resulting in an information overload in autistic individuals so that the world is experienced as overwhelming and impossible to process. There are candidate areas in the brain where this may take place,such as the temporal lobe in the region of the superior temporal gyrus. At the molecular level, adhesion molecules such as neurexin in axons and neuroligin in dendrites attract and bind with tremendous selectivity.
These connections regulate excitatory and inhibitory transmission of information in neural circuits. Were the Beatles on to something when they sang "there is something in the way you move that attracts me like no other"?