There are several other important causes of dementia in younger and older persons. Normal pressure hydrocephalus is a condition with altered absorption of spinal fluid leading to cognitive losses, gait disturbances, and poor control of urination. It may be successfully treated with surgery. Creutzfeldt-Jakob disease is a rapidly fatal progressive condition caused by a potentially transmissible form of a prion, an abnormally folded protein. Bovine spongiform encephalopathy is another prion disease associated with eating infected cows. It is now recognized that small and large head injuries are bad for the brain and can cause serious cognitive and motor deficits, and progressive untreatable dementia. Repeated blows without visible immediate effect can lead to brain degeneration. A critical way to maintain cognitive reserve is to avoid all kinds of blows to the head. Excess consumption of alcohol is very damaging to brain function and can lead to dementia, as well as nerve damage and injury to several other parts of the body, such as the liver, heart and intestines. It is recommended that men should not consume more than two doses of alcohol a day and women not more than one.