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.
For example, some people have both Alzheimerâs disease and vascular dementia. Other conditions that may cause memory loss or dementia include: 1  medication side effects. 2  chronic alcoholism. 3  tumors or infections in the brain. 4  blood clots in the brain. 5  vitamin B12 deficiency. 6  some thyroid, kidney, or liver disorders.