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.
Dementia: Irreversible Causes. Dementia has many different causes, some of which are difficult to tell apart. Many medical conditions can cause dementia symptoms, especially in older people. 1  The causes of dementia include various diseases and infections, strokes, head injuries, drugs, and nutritional deficiencies. Like Alzheimer's disease, Lewy body dementia is not reversible and has no known cure. 2  The drugs used to treat Alzheimer's disease also benefit some people with Lewy body disease. 3  Huntington's disease: This inherited disease causes wasting of certain types of brain cells that control movement as well as thinking.