Mood Stabilizers: These drugs can help reduce mood swings and prevent manic and depressive episodes in bipolar disorder by regulating the primary excitatory (glutamate) and inhibitory (GABA) neurotransmitters in the brain. Excitatory neurotransmitters increase the activity of the brain, while inhibitory ones slow the brain down. 

Antipsychotic medications reduce levels of excitatory neurotransmitters, primarily dopamine, with the goal of controlling and reversing psychosis. In healthy amounts, dopamine can improve many functions, such as focus and motivation, but when the production of dopamine is too high, the brain becomes dysregulated and connections within the cortex become unstable; as a result, overproduction of dopamine is associated with psychotic symptoms such as hallucinations, delusions and disordered thinking in schizophrenia and psychosis during mania.

Antidepressant medications increase the activity of serotonin, norepinephrine and dopamine to return the underactive brain to a state of functionality and stability.  As a result, by increasing brain activity across the brain, antidepressants alleviate physical, cognitive, and mood-related symptoms of depression. 

Antianxiety medication promotes the productivity of GABA throughout the brain, which significantly lowers the hyperactivity of the amygdala, which helps you feel soothed and more in control of your emotions.

Stimulant medications increase dopamine in certain areas of the brain, particularly the prefrontal cortex. This boost of stimulation can help a normally restless and disordered person feel more confident, energetic, and better able to think clearly and regulate one's attention and focus. For this reason, stimulants are prescribed for people with ADHD.