Autism as One of the Serious Genetic Diseases - Term Paper Example

Autism Angelica Pierce PSY 5410 David Horner November 20, of the Rockies Autism is one of the serious genetic diseases which create problems in social interactions, language learning and behaviours etc. More than 90% of the causes of autism are related to genetics or heredity. Even though, medical science has advanced a lot, so far no effective medicines or treatment options were developed to tackle autism. Autistic patients may exhibit extra ordinary skills in some areas of learning whereas they may lack skills in other areas. Even though, many genetic factors are suspected as the major causes of autism, some neurotransmitters, synapses and malfunctioning of the neurons etc seem to be more relevant. This paper specifically focuses on how biology impacts psychology and analyses the structure of the brain, neuron activities, synapses activities, activities of neurotransmitters etc in relation with autism. Autism “Autism is a neurodevelopmental disorder of genetic origins, with a heritability of about 90%. There is no single biological or clinical marker for autism, nor is it expected that a single gene is responsible for its expression; as many as 15+ genes may be involved. No single region of the brain or pathophysiological mechanism has yet been identified as being associated with autism. Postmortem findings, animal models, and neuroimaging studies have focused on the cerebellum, frontal cortex, hippocampus, and especially the amygdala. The cerebello-thalamo-cortical circuit may also be influential in autism. There is evidence that overall brain size is increased in some individuals with autism (Santangelo & Tsatsanis, 2005). Environmental influences can also cause autism along with genetic factors; however genetic factors seem to be the major reason for autism in more than 90% children with autism. Autism is considered as a developmental disorder. At the same time it is a genetic disorder also. In other words, autism is a mental disorder which affects the physical, emotional, social and behavioral development of a child. Psychologists included autism among the pervasive developmental disorders (PDD). Autism mainly affect three areas of development; social interaction, language development and behavioral patterns. At present medical science has no answer or treatment to this serious psychological disorder. So far no effective drugs have been produced for the treatment of autism. Structure of the brain plays a vital role in causing autism. Neurophysiological functions believed to cause this disorder. In fact, the defect caused in the signals sent and received by brain using the neurotransmitters and neurons is causing autism. Autism and structure of the brain Autism is a static encephalopathy with fixed core neurobiological or brain abnormality resting upon hardwired architectural alterations in tissues that may be otherwise healthy (Herbert 2005, p.358). The following illustrations will give a rough idea about the brain structure and activities of a normal person. (Herbert 2005, p.359) From the above figure it is clear that the gene influences the brain and brain influences the behavior of a person. In other words, genes can influence the behavior of a person with the help of the brain. But genes undergo several altered molecular and cellular mechanisms, altered tissue metabolisms and altered connectivity and processing before controlling the behavior of a person. In short, most of the behaviors of a person are genetically motivated. In children with autism, the genes which control the behaviors will not operate properly and hence the person will behave indifferently in the society. One of the interesting aspects of children with autism is that they may demonstrate higher skills in difficult subjects whereas they may show poor skills in comparatively easy subjects like languages. Neuroscientists from the University of Louisville working with researchers in laboratories in New York, the Netherlands and Germany examined brain tissue from individuals with autism and neurotypical samples and concluded the following things; The differences in the brain structure which may help explain why people with autism often have higher skills with such things as mathematics and visual discrimination but have problems with speech and recognizing faces. Tiny strands of connected tissue in the brain which carry messages are narrower and more densely packed in individuals who have autism (Thompson, 2006) Brain enlargement is one of the major characteristics of children with autism. This shows that the people with autism may have brains of bigger size than the normal children; however, their brain need not be developed uniformly as in the case of normal children. Some part of the brain might be more developed whereas some other parts might be underdeveloped. Because of the above reasons, children with autism may exhibit better skills in learning some topics whereas they exhibit poor skills in learning other topics. The development of computer related technologies have helped the researches in the field of autism immensely. Using computerized imaging, modern medical scientists have proved that abnormalities existing in the areas of brain that control speech and senses among autistic patients which in turn explains the deviant behaviors of autistic patients with respect to social interactions, unclear speeches and the aggressive behaviors toward any changes in the activities. Researchers after the comparative study of the brains of the autistic and normal people concluded the following things; Basic differences are there in the size and number of structures called minicolumns between the normal and autistic people (Minicolumns are basic organizational units of brain cells. They act as connective wiring, allowing a person to take in information, process it, and respond). Autistic patients had smaller minicolumns, but also many more of them compared with healthy individuals. If autistic brains have more minicolumns, but not the necessary processing capacity required to interpret and make sense of all that information, then the brain becomes flooded by "noise" -- incoming signals that put too much strain on the brain (Vogin MD, 2010) Autism and neuron activities Some researchers believe that mirror neurons in the brain are causing autism. Neurons which acts and observes the actions of another person or animal can be referred as mirror neurons. The name mirror neuron is given because these neurons copy the actions of the other exactly as did by the other person. This is why some birds speak like the humans or some people imitate others exactly. Some researchers believe that the defects in the mirror neuron functioning may prevent the autistic person from learning from the surroundings. But the relationships between mirror neuron and autism are still controversial because of the contrasting results obtained in different studies. Callaway, (2010) has mentioned several studies which yielded contrasting results with respect to the involvement of mirror neurons in autism. Ilan Dinstein, a neuroscientist at the Weizmann Institute in Rehovot, Israel, argues that “people with autism seem to have normal "mirror" neurons after all”. After a comprehensive research conducted among autistic patients, he concluded that “the brain cells that fire both when you perform an action and when you watch someone else doing the same thing – dont work properly in people with autism”. However, researchers like Mirella Dapretto and Marco Iacoboni, neuroscientist at the University of California, Los Angeles, adds that it is not possible completely to rule out the idea that mirror neurons could be behaving abnormally in autism (Callaway, 2010). In short, the function of the mirror system is a subject of much speculation. Many researchers in cognitive neuroscience and cognitive psychology consider that this system provides the physiological mechanism for the bondage between perception and action. It is a fact that mirror neurons are responsible for understanding the actions of other people, and for learning new skills through imitation. However the relationships between mirror neuron dysfunction and autism is inconclusive so far and further researches are necessary before accepting or rejecting the involvement of mirror neurons in autism. Autism and synapses activities Huda Zoghbi, a pediatric neurologist at Baylor College of Medicine in Houston, TX, first proposed that the origins of autism are at the synapse in 2003. Synapses are “junctions across which neurons communicate” and are essential for “virtually all brain function”—memory, sensory perception, motor coordination, learning. Zoghbi’s hypothesis rested on research done by a group led by Thomas Bougeron of the Pasteur Institute in Paris that found mutations in proteins called neuroligins in two pairs of Swedish brothers who have autism. Neurologins ensure that signal transitions between nerve cells function and are “expressed on the surface of the postsynaptic neuron” and bind to neurexins, which are proteins on the presynaptic neuron. It is thought that neuroligins and neurexins together “play key roles in the forming and functioning of synapses.” Bougeron has postulated that there is a “neuroligin autism pathway” in which “abnormalities in any of these dozen or more proteins could predispose their possessors” to autism spectrum disorder (Chew PhD, 2007) Another suspected culprit which causes autism is the synapse. It is the junction across which neurons communicate. Neurons are responsible for all the communication between the brain and the body. Neurons are the information carriers. Brian analyses the information collected by the neurons and give instructions to the body parts through the neurons. In other words, coding and decoding of information takes place in the brain with the help of neurons. In fact all the human activities are controlled by the neurons and the brain. In other words, proper transmission of information to and from the brain is necessary for the physical and mental activities of a person and for that purpose the safe and normal functioning of neurons are necessary. At the same time these neurons are operating across a junction called synapse. If the junctions or the synapses malfunction, the proper communication between neurons and brain or body may not take place which is another reason suspected for autism. Using an animal model, brain researchers in Göttingen have examined the effects of mutations that cause autism in humans. The study published in the scientific journal, Neuron (September 21, 2006), shows that neuroligins ensure that signal transmission between nerve cells functions. In the brain of genetically altered mice without neuroligins, the contact points at which the nerve cells communicate, the synapses, do not mature. The researchers assume that similar malfunctions are experienced by autistic patients (Autism is a disease of the synapses, 2006,p.1) Autism and activities of neurotransmitters As mentioned earlier, the actual causes of autism are still unknown to us even though we suspect many genetic factors and the malfunctions of the brain. One such suspected culprit is the neurotransmitters. The finger points towards neurotransmitters is because of the fact that a substantial differences between autistic and non-autistic individuals are seen in the structure of the brain, electrical wiring and the level of certain neurotransmitters in blood and spinal fluid. One of the major neurotransmitter under suspicion is the serotonin which controls the sleep, mood, some types of sensory perception, body-temperature regulation and appetite etc. In fact malfunctioning of serotonin is the major cause for many of the psychological diseases like depression, anxiety, schizophrenia etc. It also causes liberation of hormones and in some cases, it causes tissue inflammation also. The larger head or brain of autistic patients can be better understood when we realize the influences of serotonin in inflaming the tissues. Individuals with Autism are known to have increased levels of serotonin in their blood. They produce, absorb or metabolize serotonin differently than those who are not autistic. The values for overall serotonin synthesis in the brains of autistic patients are also significantly different. Dr. Harry Chugani, the Director of the Childrens Hospital of Michigan PET Scan Center reports that "[I]n nonautistic children, the values for serotonin synthesis change during development, such that the values for children between 3 and 8 years old are three times higher than those measured in adults. In the autistic children between the ages of 3 and 8, serotonin synthesis values were only 1 higher than the adult values." This would suggest that especially for autistic children, medication that mimics serotonin would be helpful in targeting specific behaviours that are characteristic of autism (Holister,2000) Many other abnormalities in neurotransmitter systems have also been found in autism. For example, postmortem brain examinations conducted on many of the autistic patients have found abnormalities in glutamate neurotransmitter system, with specific abnormalities in the AMPA-type glutamate receptors and glutamate transporters in the cerebellum. Moreover, abnormal activities of dopamine or serotonin receptors have also been suspected as the reason for autism (Neurotransmitters in autism and role of calcium signalling, n.d) Psychoactive substances and its actions Psychoactive substance or drug, is a chemical substance that crosses the blood-brain barrier and acts primarily upon the central nervous system. Blood Brain Barrier (BBB) is a separation between blood and cerebrospinal fluid (CSF) in the central nervous system (CNS). Thus psychoactive substances can control the perception, mood, consciousness, cognition, and behavior of a person. These drugs can affect a persons neurochemistry. Each drug has some specific action on one or more neurotransmitter in the brain. Some drugs can increase or decrease the activities in particular neurotransmitter systems and thereby bring the person in the desired mood. Moreover, psychoactive substances can cause changes in the structure and functioning of neurons also. Psychoactive substances are able to mimic the effects of naturally occurring or endogenous neurotransmitters, or to interfere with normal brain function by blocking normal function, or by altering the normal storage, release and removal of neurotransmitters. One important mechanism by which psychoactive substances act is to block the reuptake of a neurotransmitter after it is released from the presynaptic terminal. Reuptake is a normal mechanism by which the transmitter is removed from the synapse by the presynaptic membrane (Neuroscience of Psychoactive Substance Use and Dependence, 2004, p.16) Psychoactive substances are used generally in treating the mental disorders. These substances or medicines are effective in treating most of the psychological disorders like delusions, depression, anxiety etc. At the same time psychoactive substances seem to be less effective in the case of autism. Even then, psychiatrists use these medicines extensively in the treatment of autism since no other effective options are available. Recently, the Research Units on Pediatric Psychopharmacology Autism Network reported major symptom reductions in children having both autistic disorder and high levels of irritability using psychoactive substances, risperidone. Antipsychotics have been shown to be helpful for reducing stereotypic behavior and hyperactivity as well (Aman et al, 2003, p.532) References 1. Aman M.G, Lam K.S.L, Crespin A.C (2003). Prevalence and Patterns of Use of Psychoactive Medicines among Individuals with Autism in the Autism Society of Ohio. Journal of Autism and Developmental Disorders, Vol. 33, No. 5, October 2003. 1. Autism is a disease of the synapses, (2006). Retrieved from http://www.asnc-ccc.org/Autism%20is%20a%20disease%20of%20the%20synapses.pdf 2. Chew K. PhD.(2007). Autisms Cause at the Synapse? Retrieved from http://blisstree.com/live/autisms-cause-at-the-synapse/?utm_source=blisstree&utm_medium=web&utm_campaign=b5hubs_migration 3. Callaway E. (2010). Mirror neurons seen behaving normally in autism. New Scientist Life.Retrieved from http://www.newscientist.com/article/dn18837-mirror-neurons-seen-behaving-normally-in-autism.html 4. Herbert M.R. (2005). Autism: A brain disorder or a disorder that affects brain? Clinical Neuropsychiatry. (2005) 2,6, Retrieved from http://innerexpert.com/downloads/pdf/martha.herbert--autism-brain.disorder.or.disorder.affecting.brain.pdf. p.354-379. 5. Holister E (2000). Autism and its Connection with the Neurotransmitter Serotonin. Retrieved from http://serendip.brynmawr.edu/bb/neuro/neuro00/web1/Hollister.html 6. Neuroscience of Psychoactive Substance Use and Dependence, (2004). World Health Organization 2004. Retrieved from http://www.who.int/substance_abuse/publications/en/Neuroscience_E.pdf 7. Neurotransmitters in autism and role of calcium signalling, (n. d). Retrieved from http://www.autismcalciumchannelopathy.com/Neurotransmitters.html 8. Santangelo, S.L.& Tsatsanis, K. (2005). What is Known About Autism: Genes, Brain, and Behavior. American Journal of PharmacoGenomics, Volume 5, Number 2, 2005 , [Abstract only]. Retrieved from http://www.ingentaconnect.com/content/adis/apg/2005/00000005/00000002/art00001 9. Thompson T (2006). Brain Structure and Autism. Retrieved from http://www.suite101.com/blog/traceythompson/brain_structure_and_autism 10. Vogin G.D., MD (2010). Autistic Brain Structure Is Different. WebMD. Retrieved from http://www.webmd.com/mental-health/news/20020214/autistic-brain-structure-is-different Read More