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