The effects of hormones and neutransmitters as they relate to mania and depression are extremely complex and far beyond the scope of a SharePost, but here's a capsule look at the subject.
Glands and organs in the human body produce hormones that are carried through the bloodstream and affect other bodily tissues. Perhaps the best known hormone is insulin, produced by the pancreas, which is a gland.
Nerve cells, or neurons, produce neurotransmitters, chemicals which move like lightning from one cell to the next carrying messages. Some substances, including norepinephrine, function as both hormones and neurotransmitters.
Norepinephrine and epinephrine are kicked out by the adrenal glands during stress - for example, I remember feeling a "pow" in my chest when I lost control of my car on black ice at 55 mph. The hormones helped me stay calm while I regained control.
But norepinephrine also functions as a neurotransmitter and has been implicated in both depression and mania/hypomania. Drugs that work to increase the amount of norepinephrine in the brain can relieve depression for some patients, while abnormally high levels of this substance have been found in some people during manic episodes.
The neurotransmitter serotonin helps regulate mood, sleep, appetite, memory and several other functions. Although the mechanism isn't clear, medications that raise the amount of available serotonin have been found to relieve depression.
Dopamine also affects several things, including voluntary movement, emotion, pleasure, sleep and mood. Insufficient dopamine in the brain can cause Parkinson's disease, a very serious movement disorder. Abnormally high levels of dopamine have been linked to schizophrenia and psychotic symptoms of bipolar disorder.
Much more research will be needed before scientists understand the interaction between hormones, neurotransmitters and bipolar disorder, especially since the three mentioned above alone affect so many other areas of behavior, health, function and development. As more knowledge is gained, more targeted treatments may be developed to improve our quality of life with fewer side effects than current medications.
Bouchez, Colette. Serotonin: 9 Questions and Answers. WebMD. 12 Oct 2011.
Hahn, Harley. Hormones and Neurotransmitters. The Island Syndrome. 2012.
Dopamine Functions. News-Medical.net. Undated.