Often called the ‘feel-good’ hormone, dopamine is in charge of making you feel happy, satisfied, and motivated. When you feel good because you have accomplished something, your brain experiences a dopamine spike. What occurs, though, when there is an imbalance? Could this imbalance play a role in the development of schizophrenia? This is where the dopamine hypothesis of schizophrenia enters the picture, examining how the imbalance of dopamine levels and the abundance of dopamine receptors contributes to schizophrenia. Show
Fig. 1 - The dopamine hypothesis suggests an imbalance in dopamine is why schizophrenia symptoms develop. The Dopamine Hypothesis of Schizophrenia: DefinitionThe dopamine hypothesis, first proposed by Van Rossum in 1967, is the theory that too much dopamine may cause schizophrenic symptoms. The dopamine hypothesis was later revised as research revealed schizophrenic patients may also have too many dopamine receptors, which can also contribute to the disorder. Dopamine is a neurotransmitter that helps the brain send messages to specific body parts. Neurotransmitters are chemical messengers within the brain. Neurotransmitters bind to receptors in nerve cells after they cross a small gap between them called the synapse. Dopamine is a neurotransmitter involved in our brain’s pleasure and reward systems. The receptors of dopamine are implicated in the dopamine hypothesis of schizophrenia, in that some researchers theorise too many receptors contribute to the overactivity of dopamine in the brain and any subsequent schizophrenic developments. Biological Explanations of Schizophrenia: Dopamine HypothesisThe dopamine hypothesis is a biological explanation of schizophrenia, so how does it work? What parts of the brain are involved in the dopamine hypothesis? Dopamine is produced in different areas of the brain, and for schizophrenia, we are concerned with the substantia nigra and the ventral tegmental area.
Fig. 2 - Dopamine pathways show the dopamine systems within the brain. Studies of amphetamines given to people without a history of schizophrenia showed that the effect of high levels of dopamine the drug had induced led to symptoms very similar to those of paranoid schizophrenia. Later revisions of the hypothesis stated that possibly an excess of dopamine in the mesolimbic areas of the brain contributes to positive symptoms, and a low level of dopamine in the brain’s prefrontal cortex contributes to negative symptoms. Dopamine Hypothesis of Psychosis: Development of the Dopamine HypothesisIn the 1960s and 1970s, research was conducted into the use of amphetamine drugs and their effect on dopamine levels within the brain. The researchers found that psychotic symptoms increased when these drugs were consumed, sparking the idea that dopamine may help us understand how psychotic symptoms in schizophrenia patients may come to be. The Dopamine Hypothesis: Strengths and WeaknessesThe dopamine hypothesis has been around for close to 60 years, and has gone through a series of developments alongside facing scrutiny in research. Let's evaluate the dopamine hypothesis of schizophrenia and examine its strengths and weaknesses. Weaknesses of the Dopamine HypothesisThe dopamine hypothesis, like any other, has its weaknesses.
Strengths of the Dopamine HypothesisOn the other hand, some studies are sympathetic to the role dopamine plays in the development of schizophrenia.
Fig. 3 - Parkinson's can be treated using levodopa which increases dopamine levels in the brain. Practical Applications of the Dopamine HypothesisNow that we have gained some insight into the dopamine hypothesis’s theoretical aspects, let us look at how it is applied in practice. Typical Antipsychotic Drugs: First GenerationThe dopamine hypothesis has contributed to the development of antipsychotics for schizophrenia and several other disorders in which sufferers experience psychosis. Typical antipsychotic drugs work by blocking D2 receptors in the brain, limiting dopamine activity. Blocking dopamine receptors can help reduce positive symptoms such as hallucinations Typical antipsychotics tend to block dopamine in all areas of the brain, not just those that cause schizophrenic symptoms, which can lead to harmful side effects. Examples of typical antipsychotics include chlorpromazine and haloperidol. Atypical Antipsychotic Drugs: Second GenerationAtypical antipsychotics are newer drugs that usually do not have as severe side effects as typical antipsychotics. Atypical antipsychotics only inhibit dopamine receptors in the limbic system rather than throughout the brain. They help control the symptoms of schizophrenia without interfering with other systems and potentially causing the same side effects as the previous generation of medications.Atypical antipsychotics bind to dopamine receptors and act on glutamate (an excitatory neurotransmitter) and serotonin. This means that these drugs can help with positive symptoms and reduce negative symptoms such as low mood and impaired cognitive function. Because of their effect on serotonin, these antipsychotics can also help treat some comorbidities associated with schizophrenia, such as anxiety and depression. Evaluating Practical Applications of the Dopamine HypothesisConsidering the practical applications of the dopamine hypothesis affect patients, it's important we evaluate it thoroughly before moving forwards.
The Dopamine Hypothesis - Key takeaways
Does the dopamine hypothesis explain schizophrenia?Finally, dopamine does explain the pathophysiology of schizophrenia, but not necessarily the cause per se. Rather, dopamine acts as the common final pathway of a wide variety of predisposing factors, either environmental, genetic, or both, that lead to the disease.
What does dopamine do in schizophrenia?Dopamine Hypothesis
This theory suggests that an imbalance of dopamine is responsible for schizophrenic symptoms. In other words, dopamine plays a role in controlling our sense of reality, and too much or too little can cause delusions and hallucinations.
What is the dopamine hypothesis quizlet?The dopamine hypothesis states that messages from neurons that transmit dopamine fire too easily or too often, leading to characteristic symptoms of schizophrenia. Schizophrenia is caused by abnormally high levels of dopamine in dopamine receptors.
What is the dopamine hypothesis psychology?The dopamine hypothesis of schizophrenia postulates that an excess of dopamine subcortically is associated with the positive symptoms. At the same time, the negative and cognitive symptoms of schizophrenia are thought to arise from a deficit of dopamine in the cortex.
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