The Theories Of Schizophreni Dopamine, Glutamate, Brain Abnormalities, And Nature Vs. Nurture

Schizophrenia is classified as a mental disorder that shows profound disruption of cognition and emotion which affects a person’s language, perception, thought and sense of self. The dopamine hypothesis states that schizophrenic’s neurones transmitting dopamine release the neurotransmitter too easily, leading to the characteristic symptoms of schizophrenia. This hypothesis claims that schizophrenics have abnormally high amounts of D2 receptors; receptors that receive dopamine, therefore resulting in a higher amount of D2 receptors binding to the receptors causing more impulses. Dopamine neurotransmitters play a

Expert’s reason that unevenness in the complicated interconnected chemical responses of the brain connecting the neurotransmitters dopamine and glutamate, and maybe others, performs a part in schizophrenia. Neurotransmitters are elements that permit brain cells to interconnect with each other. Experts are acquiring more about brain chemistry and its connection to schizophrenia. Similarly, in small methods the brains of people with schizophrenia appear diverse than those of healthful people. For instance, fluid-filled holes at the middle of the brain, called ventricles, are greater in certain people with schizophrenia. The brains of people with the disorder similarly manage to have less grey matter, and certain

There are two main biological theories which explain the assumed causes of schizophrenia: Genetic and Dopamine Hypothesis.

Of the six most common neurotransmitters, dopamine is probably the one people know the most about. Dopamine is involved in controlling the reward and pleasure system in the brain. It allows us to recognize rewards and helps give us the ability to go after them. Learning, behavior, and cognition are also affected by dopamine levels. As with anything, if you have an imbalance, then bad things can happen. Parkinson’s disease can be caused by low dopamine amounts. People who have low dopamine levels can be addicted to substances easier.

The major support and refutation of the dopamine hypothesis has come from the examination of dopamine receptors in these regions of the brain. There are two main types of dopamine receptors, D1 and D2. However, within the category of D2 receptors, there are three subtypes, D2, D3, and D4. (5) Through PET scan analysis of dopamine usage in the brain and post-mordum molecular analysis of brain tissue, researcher were able to determine relative levels of dopamine receptors in patients with schizophrenia compared to non-schizophrenics. Overall analysis of dopamine

Currently there are no cures for schizophrenia, but the symptoms are helped by taking antipsychotic medication. The symptoms experienced by those with schizophrenia are grouped in to three categories: negative symptoms, positive symptoms, and cognitive symptoms (Regier 1993, p.92). The positive symptoms include, hallucinations, delusions, unusual or dysfunctional ways of thinking, agitated body movements. Negative symptoms include, flat affect, reduced pleasure in everyday life, difficulty sustaining tasks, and reduced speech. Cognitive symptoms include, disruption in executive functioning and working memory, as well as reduced ability to concentrate. The etiology of schizophrenia is still debated by psychologists and neuroscientists, but factors such as neuroanatomy, and environmental influences are believed to play a key role. A genetic predisposition to schizophrenia has been established by researchers, but it remains unclear what causes the phenotype to be expressed. The most agreed upon cause of schizophrenia refers to the diathesis-stress model, which explains schizophrenia as a response to an individual’s allostatic load becoming too much for the brain to cope with. Another popular explanation amongst neuroscientists is the dopamine

Dopamine is a neurotransmitter associated with attention. Schizophrenics seem to have an increased number of D2 dopamine receptors on receiving neurons. This theory is support by the fact that Phenothiazines bind with D2 receptors and reduce positive symptoms. Another piece of supporting evidence is that Parkinson’s disease drug L-dopa, increase the level of dopamine and causes schizophrenic like symptoms in some people. However excess dopamine can only explain some types of schizophrenia, usually positive rather than negative.

Neurotransmitters are chemicals made by neurons and used by them to transmit signals to the other neurons or non-neuronal cells (e.g., skeletal muscle; myocardium, pineal glandular cells) that they innervate. The neurotransmitters produce their effects by being released into synapses when their neuron of origin fires (i.e., becomes depolarized) and then attaching to receptors in the membrane of the post-synaptic cells. This causes changes in the fluxes of particular ions across that membrane, making cells more likely to become depolarized, if the neurotransmitter happens to be excitatory, or less likely if it is inhibitory.

Biological, psychological, and sociocultural viewpoints have been developed in an attempt to explain schizophrenia. All three viewpoints point out various factors that may contribute to the development of the disorder.

Over the years, experiments have produced evidence to suggest that dopamine plays a role in the development of Schizophrenia (Howes, McCutcheon, & Stone, 2015). Dopamine is a neurotransmitter that is produced in the substantia nigra and ventral tegmental regions of the brain. The belief that dopamine was involved in Schizophrenia arose after multiple studies performed with compounds produced an increase in extracellular concentrations of dopamine (Lieberman, Kane, & Alvir, 1987). The patients that were administered these compounds had similar symptoms to those observed from patients who were diagnosed with Schizophrenia (Lieberman et al., 1987).

In the research presented by Howes and Kapur (2009), they have pointed out a possible concern to invalidate the dopamine hypothesis in schizophrenia as current PET studies did not holding a firm position in measure the dopamine level, they were more to a postulation of a generated estimation from the data. Furthermore, Howes and Kapur (2009) also stressed that the role of dopamine could be circumvented by using the antipsychotic drugs which effectively to the psychotic symptoms but neutral to the dopamine system, thus the role of dopamine will be less critical in schizophrenia. This is because most of the recent antipsychotic researches only prove that dopamine merely contributed in providing a solution in alleviating the psychosis-liked-symptoms but those symptoms are not the symptoms only existed in schizophrenia.

There are four kinds of schizophrenia, including paranoid schizophrenia, disorganized schizophrenia, catatonic schizophrenia, and undifferentiated schizophrenia. Causes are not clear, and biological, psychological and environment factors are being investigated. It is certain that there is a genetic component. (Passer and Smith, 2004)

Dopamine is a brain chemical/Neurotransmitter that work as messenger signal between the Substantia Nigra to the next relay station of the brain, the corpus striatum which helps to produce smooth coordinate movement and also plays a major role to help control muscle’s movement. With Parkinson’s disease, the brain cells that produce dopamine slowly die, which lead to decrease production of Dopamine. The loss of dopamine causes abnormal nerve firing with brain and the cells that control muscle’s movement by sending the messages to the muscles; due to this it becomes really hard to control muscles movement and cause tremors and various other symptoms such as rigidity and difficulty walking and performing daily tasks. Dopamine is not the only neurotransmitter involved in Parkinson’s Disease. Norepinephrine is very relatively close to dopamine and is also involved in Parkinson’s Disease. Individuals with Parkinson’s Disease have loss of nerve ending that produce norepinephrine. Norepinephrine is a major neurotransmitter for sympathetic nervous system, which control many autonomic functions of our body; it causes increase in blood pressure and heart rate. Loss of norepinephrine can help us explain the non-motor symptoms associated with Parkinson’s Disease such as fatigue, decrease in gastric stability and disruption in cognition. Parkinson’s Disease can be hereditary

The Dopamine Hypothesis theorizes that the symptoms portrayed in Schizophrenia is can be explained by abnormal function of dopamine in the brain. There have been three versions of the Dopamine Hypothesis. The first version of the hypothesis focuses on the dopamine receptors. Antipsychotic drugs that impact the metabolization and reabsorption of dopamine where found to be effective in treating the symptoms. It was theorized that if the symptoms of a Schizophrenic episode can be treated by the use of dopamine

The D2 Receptor of dopamine has an extremely important function in the nervous system. The D2 receptor is found as metabotropic which means it is coupled with a G-Protein Linked Receptor. It is found pre-synaptically as D2Sh which is also known as an autoreceptor. The D2Sh isoform of D2 receptor can regulate neurotransmission as well as affect synthesis, storage, and release of dopamine into the synaptic cleft. The heteroreceptor isoform of D2 receptor is known as D2Lh which