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can someone explain me what is the role of dopamine in psychosis and schizophrenia. somewhere on the internet i read that low dopamine is associated with diseases like psychosis and schizophrenia. And somewhere on the internet i read: "The dopamine hypothesis of schizophrenia postulates that hyperactivity of dopamine D2 receptor neurotransmission in subcortical and limbic brain regions contributes to positive symptoms of schizophrenia". does this mean high levels of dopamine cause psychosis and schizophrenia. I am so confused please clarify this. Also low levels of serotonin causes depression and the anti depressants increase serotonin levels thus treating depression. But doctor prescribed me anti depressants and anti psychotics at the same time. As second generation antipsychotics that doctror prescribed me are known to be serotonin and dopamine antagonists, then how do both of the medecations work simultaneously?

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    $\begingroup$ There is not a sufficient understanding of how neurotransmitters and antipsychotics work; antipsychotics are prescribed because clinical trials show they are effective in preventing symptoms of psychosis, not because we fully understand psychosis in the brain. Neurotransmitter "levels" don't tell nearly the whole story, because there is a constant homeostatic balance occurring in the brain between receptor expression of many different types having different effects. You can have paradoxical effects where increasing a neurotransmitter decreases its efficacy at certain synapses, or vice versa. $\endgroup$
    – Bryan Krause
    Sep 15 '21 at 16:11
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    $\begingroup$ Answering the actual title question here would mean summarizing books upon books of knowledge, much of it conflicting and without a simple story. $\endgroup$
    – Bryan Krause
    Sep 15 '21 at 16:12
  • $\begingroup$ "somewhere on the internet i read" link to what you have read. I.e., provide citations. $\endgroup$
    – Steven Jeuris
    Sep 17 '21 at 17:21
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It would have been better if you had split your question into two (one involving psychosis and the other depression) and provide each in a separate stack exchange post.

Schizophrenia is said to be caused by excessive increase in the level of Dopamine in the brain. On the other hand, low level of Dopamine is implicated in Parkinson disease. In connection with schizophrenia In this instance, dopamine act as an excitatory neurotransmitter (that is, it increases the activity of the nerve cells).

Drugs that are used for treating schizophrenia tend to block Dopamine receptors. When such receptors are blocked, the effect of Dopamine will be reduced. Dopamine receptors have five subtypes: D1-, D2-, D3-, D4- and D5-type receptors. Generally, first generation antipsychotic agents block all the dopamine receptors without discrimination. The antisychotic effect occurs when the drugs block the D2-, D3- and D4-type receptors. There are different dopaminergic pathways in the brain, namely: mesolimbic, nigrostriatal, tuberoinfundibular etc. It's the blockade of D2, D3 and D4 type receptors in the mesolimbic pathway that relieves the positve symptoms of schizophrenia. Just as there is dopamine hypothesis,

The first version of this hypothesis stressed the role of the excess of dopamine but it was developed into an idea linking prefrontal hypodopaminergia and striatal hyperdopaminergia and then to the current aberrant salience hypothesis

(Source: https://pubmed.ncbi.nlm.nih.gov/19325164/)

So also there is serotonin hypothesis of schizophrenia that attributes the cause of schizophrenia to excessive increase of serotonin.

You said your doctor prescribed both antipsychotic and antidepressant for you. Well, he might have explained to you why he prescribed both medications. Because no two persons are exactly the same, treatment is narrowed down to suit the need of each individual after putting different factors into consideration. So, your doctor is in the best position to explain why he prescribed both medications. It might be that he's treating bipolar disorder in a closely monitored setting.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6222385/

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