Understanding the differences between psychotic disorders, like schizophrenia, and affective disorders, like depression, can help us better comprehend these conditions. Here are some key points:

1. Brain Structure:

   • People with schizophrenia have smaller brains, which means their total brain size is about 11% less than average.
   • Those with major depressive disorder usually have a smaller part of the brain called the hippocampus. This area is important for memory, and it is about 10% smaller on average.

2. Brain Chemicals:

   • In psychotic disorders, the brain has too much of a chemical called dopamine. Studies show there are 40-60% more D2 receptors, which are the spots in the brain that dopamine connects to.
   • Affective disorders, like depression, have a problem with another chemical called serotonin. Around 70% of people with depression have issues with their 5-HT receptors, which means serotonin isn’t working well in their brains.

3. Inflammation Markers:

   • About 30% of people with psychotic disorders have higher levels of certain chemicals in their bodies that cause inflammation. One of these is called IL-6.
   • In people with affective disorders, only about 18% show these inflammation markers.

These findings show that there are important differences in how psychotic disorders and affective disorders work in the brain and body. This helps researchers understand what might be happening when someone has these conditions.