1 DNA and proteins are key molecules of the cell nucleus. 2  One gene makes one protein. 3  A gene is made of DNA. 4  Bacteria and viruses have DNA too. 5  The DNA molecule is shaped like a twisted ladder. 6  A half DNA ladder is a template for copying the whole.  RNA is an intermediary between DNA and protein.
1 Another theory holds that depression may directly damage the brain, leading to dementia. âSimply put, chronic stress and/or depression may result in the release of cortisol,â Gorman says. Over time, this stress hormone can harm the brain, she says.  A third theory points to reduced brain volume.
The wide range of potential causes has lead to the development of numerous depression treatments. Biological Cause of Major Depressive Disorder. A change in brain activity is almost always associated with major depressive disorder. There is decreased activity in the left frontal lobe during depression and a rise in activity following stabilization of mood. These discrepancies between over-active and under-active regions of the brain are at the biological cause of major depressive disorder. Neurotransmitters Could Cause Depression The release and reuptake of neurotransmitters (serotonin, norepinephrine, and dopamine) in the brain is linked to a personâs mood.