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.
Subscribe to our Managing Depression e-newsletter to stay up to date on depression topics. It's not known exactly what causes depression. As with many mental disorders, a variety of factors may be involved, such as: 1  Biological differences.2  People with depression appear to have physical changes in their brains. 3  The significance of these changes is still uncertain, but may eventually help pinpoint causes.4  Brain chemistry.ubscribe to our Managing Depression e-newsletter to stay up to date on depression topics. It's not known exactly what causes depression. As with many mental disorders, a variety of factors may be involved, such as: 1  Biological differences.