There are chemicals in the body that work within brain regions to regulate mood and behavior. In depressed patients, there are imbalances of certain chemicals. Thus, depression can be explained in part by biochemical causes. There is also some insight into which areas of the brain these biochemical substances affect.
Controversy
The attribution of biological chemicals to the occurrence of depression has sparked controversy, but studies consistently show evidence that it does play a role in depression. Much of the controversy revolves around the belief that the pharmaceutical industry stretches scientific findings in order to support a biochemical cause of depression. The alleged reason is to have a basis for marketing selective serotonin reuptake inhibitors, according to an article published in September 2008 in "Trends in Pharmacological Sciences."
Mechanism
Despite these allegations, it is clear that the brains of depressed patients do not function in the same way as brains of non-depressed individuals, as mentioned in "Trends in Pharmacological Sciences." Specifically, considerations are given to neurotransmitters and other biochemical substances that have the job of sending signals across the brain. When levels of these biochemical substances are altered, communication in the brain is interrupted, thereby causing disturbances in mood.
Location
Two brain areas are linked strongly to depression, the frontal lobe and the amygdala, which work inter-connectedly to regulate mood. The frontal lobes control functions such as memory, attention and the ability to control impulses. These functions are impacted by the altered levels of biochemical substances identified in depressed individuals, according to an article published in April 2009 in "Psychiatry Research."
Components
Serotonin is one biochemical inside the brain and receives the most attention with regard to depression. Another biochemical substance is choline, which is generally involved with breaking down fats. The body can make choline so it is not truly a vitamin, as commonly thought. Choline levels detected in the brains of depressed people were significantly lower than those of non-depressed patients, according to the findings of the study published in "Psychiatry Research." Dopamine is another biological chemical whose levels are altered in depressed people. Dopamine is involved with reward feelings related to things such as food, sex and drugs, according to "Biological Psychiatry."
Considerations
Older adults are predisposed to getting depression because of slightly different brain circumstances. Specifically, depressed older adults are more likely to have hyperintensities in the brain. Hyperintesity is high intensity of brain activity revealed on an MRI bran scan. Hyperintensities are found in patients with psychiatric illnesses such as bipolar depression, but it is also a common aspect of aging.
References
- "Trends in Pharmacological Sciences"; Serotonin and Depression: Pathophysiological Mechanism or Marketing Myth?; Phillip J. Cowen; September 2008
- "Psychiatry Research"; Biochemical Abnormalities of the Medial Temporal and Medial Prefrontal Cortex in Late-Life Depression; T. N. Venkatraman et al.; April 30, 2009
