Dopamine Upregulation

Dopamine upregulation refers to the brain's ability to compensate for neuroreceptor blocking. There are many similarities between the brain and a computer but a computer cannot adapt and compensate for changes in its processing. The brain can although nobody is quite sure how. The conventional antipsychotics like Haldol, thorazine, stellazine and a dozen others were all effective by blocking Dopamine D2 receptors. They blocked 60-70% of D2 receptors throughout the brain at a therapeutic dose. And people took antipsychotics daily for five, ten, fifteen, years without missing a day. Researchers speculated that the brain might adapt to that D2 blockade but until modern brain imaging technology became available no one thought about it very much.

Last year I chatted with a researcher from the Centre for Addiction and Mental Health in Toronto. He had taken three patients with schizophrenia who had been taking conventional antipsychotics for at least five years. He took them completely off their medication in the hospital and then used a PET scan to find out how many Dopamine D2 receptors they had. They had to be off their medication so that all D2 receptors could be open. He found they each had 50%-100% more D2 receptors then an ordinary person. Their brains had compensated for the D2 blocking antipsychotic by creating more D2 receptors. That is called dopamine upregulation.

There is up regulation and down regulation. The question is would these brains have eventually compensated for the removal of the conventional antipsychotic by reducing the number of D2 receptors, and how long would that take? Not so long ago schizophrenia was thought to be caused by a surplus of Dopamine D2 receptors, because medication blocked D2 receptors. Such a theory was much too simplistic. It is known to be much more complicated then that now. I have read though that psychosis is still thought to be caused by surplus dopamine, particularly symptoms like hearing voices. So if someone suddenly stops taking their medication they are very likely to develop psychotic symptoms, because their brain is suddenly experiencing twice as much dopamine stimulation as a normal person would. They essentially have twice as many receptors, and twice as much dopamine. Their psychotic episode may not be caused by their schizophrenia so much as their sudden noncompliance.

Dopamine upregulation is not a problem as long as someone continues to take their conventional antipsychotic. When they switch to an atypical medication though you might see some problems because

Go To Page: 1 2 3