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.
But it is possible that, like depression, it may be physically, as well as psychologically, linked to AD. AD can also co-occur with psychotic conditions. Older adults with schizophrenia, for example, are as likely to develop AD as those without severe mental illness. And individuals with schizophrenia in old age are at higher risk for depression, creating the possibility of all three co-occurring mental disorders.