Explaining child disorders

• What is autism
• Types of autism
• Causes of autism
• Sociology facts of autism

Causes of autism The causes and etiology of autism are areas this  and  its  effects  are  still  unknown. of debate and controversy; there is currently no consensus, and researchers are studying a Research has not yet established exactly what wide range of possible genetic and is specific to autism and what may be seen in environmental causes. Since the way autism other  disorders  however. manifests is different for each person, there are likely multiple "causes" that interact Individuals with autism are also far more with each other in subtle and complex ways, likely to develop epilepsy than would and thus give slightly differing outcomes in otherwise be expected (estimated 10-30% each individual. Two environmental theories incidence). include the impact of vaccines on the immune system (of which a statistically significant Genetic  component link has never been found despite many attempts; see the vaccine theory for a more Genetic influence comprises a significant extensive treatment) and a more recent theory aspect of research in the causes of autism. A relating autism to high levels of television large database showing theoretical links viewing while young. A correlation has also between autism and genetic loci summarises been found between autism and the mercury research indicating that the genetic emitted from coal power plants, though the influence may extend to every human implications of this correlation is chromosome. It has been observed in one uncertain. Mercury measurements of hair twin-study in Britain that there was about a samples from autistic children's first 60% concordance rate for autism in haircuts were significantly lower than a monozygotic (identical) twins, while matched group of normal children, declining dizygotic (non-identical) twins and other as  measures  of  severity  increased. siblings comparatively exhibited about 4% concordance rates. Some research posits that Research claims also link autism with the chances that an identical twin of an abnormal blood vessel function, and oxidative autistic person will also be autistic are stress. This line of research may lead to new 85-90%. The increased probabilities of medical  therapies. siblings having autism has been calculated at about  35-fold  more  than  normal. Physiology  and  neurology Accompanying impairments are also a common Autism appears to involve a greater amount of feature of autism. Some people with autism the brain than previously thought. A study of also have gastrointestinal, immunological or 112 children (56 with autism and 56 without), neurological symptoms in addition to published in the Journal of Child behavioral impairments. These associated Neuropsychology, found those with autism to complexes have also lead to the search for have more problems with complex tasks, such specific genetic connections and helped to as tying their shoelaces or writing, which focus  on  reasonable  genetic  implications. suggests that many areas of the brain are involved. Children with autism performed Since genes provide the information for simple tasks as well as or better than those processes and structure at the level of the without. In tests of visual and spatial cell and its components during the growth and skills, autistic children did well at finding development of a human as well as maintenance small objects in complex pictures (e.g., during life, gene mutations (altered finding the character Waldo in "Where's versions) and deletions (complete absence of Waldo" pictures). However, they found it genetic material) and possibly extra copies difficult to tell the difference between of genes would mean that the causes of autism similar-looking people. Children with autism begin very early. If a mutated gene fails to tended to do well in spelling and grammar, perform properly, then cells, proteins, but found it much more difficult to enzymes and other crucial aspects of normal understand complex speech, such as idioms or function may be significantly altered and similes when the meaning of the phrase is operate incorrectly. Deletions could mean the figurative. They would, for example, not complete absence of a sequence of events due understand that "He kicked the bucket" meant to missing proteins or cell components for someone had died, or were likely to actually example. These genetic alterations and hop  if  told  to  "hop  to  it". deletions will simply bring about a changed structure or process which effects a great The inference from this research, according many  other  needed structures and processes. to researchers at the Pittsburgh School of Medicine, is that "These findings show that Another important aspect of research in you cannot compartmentalize autism. It's much genetic factors is environmental effects and more  complex.” the incidence of autism. During the lifetime of a person, gene mutations and deletions may The research from this perspective has a be environmentally triggered or exacerbated. number  of  implications: Conversely, it may also be that environment will not be a factor and nothing will change Autism is more than likely a global disorder the autism characteristics. For autism, the which affects how the brain processes the answer to these possible explanations is information it receives, while complex still being researched and there is evidence information tends to make this more readily that both may be true simply because there is apparent. more than one way a person may develop autism. Neurological ‘wiring’ in people with autism manifest abnormalities in the Deletions  and  Mutations areas of the brain that communicate with each other. Deleted genes have been noted as a probable influence or cause in autism. By locating Observed abnormalities provide a reasonable specific missing genetic material the explanation for why children with autism have significance may be that specific genetic problems with complex tasks which require sites for autism controlling or causing multiple areas of the brain to work together; autism (autism susceptibility alleles) may be autistic people tend to do better in tasks located precisely. Another significant aspect that  only  require  one region of the brain. of this research is that these deletions of genetic material indicate that autism may be The causes of autism are possibly more established in some cases during meiosis pervasive than previously believed; for (error-prone meiosis model) and this places example, more areas of the brain are affected the genesis of autism in some at the very than just those involving social interaction, beginning  of  life. communication,  interests,  and  imagination. One very important question in this line of Autism may not be primarily a disorder of research is whether or not gene deletions are social interaction; research must now take a cause or consequence of into  account  non-social  aspects. autism-susceptibility loci located elsewhere in  the  chromosomes. A possible explanation for the characteristics of the syndrome is a Gene mutations may mean a gene does not variation in the way the brain itself reacts function at all or does not function in the to sensory input and how parts of the brain normal way. Since genes direct how the body then handle the information. An grows and develops, mutations, like electroencephalographic (EEG) study of 36 deletions, will effect a person at the most adults (half of whom had autism) at basic  levels. Washington University in St. Louis found that adults with autism show differences in the Mutation and deletion effects have been manner in which neural activity is delineated in numerous research publications. coordinated. The implication seems to be that there is poor internal communication between Correlated characteristics include global different areas of the brain. developmental delay, mild to severe delay of (Electroencephalographs, or EEGs, measure the speech, social communication disorders and activity  of  brain  cells.) cognitive abilities, autistic like behaviour, high tolerance of pain, and repetitive The study indicated that there were abnormal mannerisms  (e.g.  chewing  or  mouthing). patterns in the way the brain cells were connected in the temporal lobe of the brain. Gene interaction may also complicate the (The temporal lobe deals with language.) causes leading to multiple genetic origins of These abnormal patterns would seem to autism, In a cascade like effect, when a gene indicate inefficient and inconsistent loci is altered or omitted, others are communication inside the brain of autistic effected due to change in interaction between people. genes  and/or  their  functions. Studies in neuropathology indicate Though not present in all individuals with abnormalities in the amygdala, hippocampus, autism, these mutations and deletions hold septum, mamillary bodies, limbic system, and potential to point the way to more the the  cerebellum. genetic components of spectrum disorders. The research also advanced basic understanding in Autistic brains are slightly larger and the genetic architecture of the genome of heavier and a larger than normal head autistic individuals and will help in circumference  is  commonly  noted. focusing  future  research. In the limbic system, there is an excess of One practical aspect of this type of research cells and they are too small. The neurons may be the development of a test that would themselves appear to be underdeveloped. confirm the autism diagnosis in children Dendritic trees which provide the basis for exhibiting symptoms and identify families who connections between neurons are truncated carry genetic defects that could be inherited (i.e.  shortened). by  their  children. In the cerebellum, purkinje cells are widely Mirror  neurons affected. The anatomic differences correlate to the curtailment of development earlier A theory featuring mirror neurons states that than 30 weeks gestation. In other words, the autism may involve a dysfunction of development of the cells appears to have specialized neurons in the brain that should stopped at some time before the 30th week in activate when observing other people. In utero typically-developing people, these mirror neurons are thought to perhaps play a major An enlarged third ventricle of the brain part in social learning and general appears to accompany autism in those who are comprehension of the actions of others. non-mentally retarded, but the reasons for 1 A B C D 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95