Fluctuations of chemicals that occur in the brain affect how it operates. These chemicals have many different functions. According to InteliHealth.com they send messages, open and close gates in cells and regulate production of proteins. An excess or deficiency of a particular chemical in the brain may cause various problems, including depression.
Neurotransmitters
Discovery Health indicates that neurotransmitters are chemicals in the brain that facilitate communication between nerve cells or neurons. Several types of neurotransmitter believed associated with the development of depression include serotonin, norepinephrine and dopamine. As all neurotransmitters serve many purposes throughout the body and brain, understanding how these chemicals causes depression remains unclear. However, when insufficient or excessive quantities of these neurotransmitters occur in the brain, observation indicates that it may cause or contribute to the development of depression.
For example, a class of drugs called selective serotonin reuptake inhibitors, or SSRIs, work to increase the amount of serotonin available in the brain. This in turn often alleviates some or all symptoms of depression for many individuals. This lends credence to the belief that deficient amounts of serotonin contribute to depression, as increasing the amounts available appears to improve the problem.
Hormones
According to InteliHealth.com, hormones circulate through the bloodstream and broadcast messages to collections of cells and organs. Dr. Aaron Beck and Dr. Brad Alford in the book "Depression: Causes and Treatment" indicate that excess amounts of adrenal hormones, such as cortisol, have been implicated in the cause of some psychiatric problems, including depression. Other studies suggest that the excess in hormones may be due to the depression. Therefore, while it seems apparent that adrenal hormones play a role in depression, the question of pinpointing it as a cause remains unanswered.
Hormones produced by the thyroid gland have an association with the cause of depression. Discovery Health states that an underactive thyroid or hypothyroidism may cause depression.
Sex hormones, particularly ones found in females, are thought to be associated with depression. Fluctuating hormones during menstrual cycles, menopause and childbirth often cause mood changes in women. Discovery Health notes that four out of 10 women experience mood changes prior to menstrual cycles and "5 percent of women experience serious depression during premenstrual periods."
Other Chemicals
InteliHealth.com indicates that ongoing study continues regarding that roles that other chemicals may play in causing depression. These chemicals include enzymes, secondary chemical messengers and proteins. At this time, limited information is available regarding these chemicals suspected roles in depression.
References
- Aetna InteliHealth: The Role of Neurotransmitters And Hormones in Depression
- "Depression: Causes and Treatment, 2nd Edition"; Aaron T. Beck, M.D. and Brad A. Alford, Ph.D.; 2009
- Discovery Health: The Chemical Connection; Bobbie Hasselbring
- National Institute of Mental Health: Depression
