Written by Melissa Lingohr-Smith
28 November, 2018
Bipolar disorder, also known as manic-depressive disorder, refers to a group of mood disorders that varies in the severity of episodes of mania and depression and the predominant type of episode. Certain chemicals, also called neurotransmitters, act as messengers between neurons in the brain. A study in the October 2000 issue of the “American Journal of Psychiatry” reports that several neurotransmitters have been implicated as causal of the disease, but additional factors contribute to the disorder, including structural differences in areas of the brain. Also, genetic and environmental triggers contribute to the development of bipolar disorder. The neurotransmitters suspected of being involved in mediating the symptoms of bipolar disorder regulate mood, stress, pleasure, reward, sleep, arousal, concentration and attention, among other higher cognitive functions.
Serotonin
Serotonin is a neurotransmitter that is synthesized from the amino acid tryptophan. Decreased levels of serotonin are commonly found in patients with bipolar disorder and depression. Many antidepressant medications, including monoamine oxidase inhibitors, selective serotonin reuptake inhibitors and tricyclic antidepressants reduce the symptoms of depression by increasing the concentration of serotonin in the brain.
Glutamate
The amino acid glutamate is the most abundant excitatory in the brain. A study published in the December 2007 issue of “Biological Psychiatry” reports that glutamate levels are higher in certain regions of the brain in patients with bipolar disorder 2. Many mood-stabilizing drugs used to treat bipolar disorder are known to decrease the excitatory actions of glutamate.
GABA
Gamma-amino butyric acid, or GABA, is an inhibitory neurotransmitter synthesized from the amino acid glutamate. GABA modulates the activity of several other neurotransmitters, including dopamine, serotonin and norepinephrine. An article in the July 2001 issue of “Neuropsychopharmacology” states that the actions of GABA in the brains of bipolar patients are significantly blunted.
