The term dementia refers to a number of brain diseases that cause the sufferer to have impaired thinking and lead to a decrease in the quality of life. Processes such as memory, decision making and facial recognition are often affected. There is no cure because it occurs due to the degeneration of brain tissue which is irreparable.
The recorded history of the disease goes back a long way, at least to the time of the Ancient Greeks, where it was mentioned by Pythagoras in 7BC. He described it as a return to infancy, because of the loss of independence and rational thinking. The Ancient Greeks considered it to be an inevitable state of the elderly but this is not considered to be accurate today.
At a more recent point in history, Victorians used the term 'senile dementia' because they believed it was not just present in the elderly; the word 'senile' appears in front of mental illnesses to show it is a condition present in an elderly person. They thought that the illness could appear in younger people too and it could be caused by shock or mental exhaustion. It was considered to be a form of incurable, progressive insanity. They were treated in asylums and known as 'lunatics', which in those days was a legal term to define people who were in lunatic asylums and it often appeared on the census.
The actual word 'dementia' was coined in the 17th Century by a French doctor called Dr. Philippe Pinel who used the term 'demence' which described a patient who demonstrated incoherence in her mental faculties. She couldn't remember how to use everyday utensils and had forgotten how to speak. After her death he examined her brain and found the tissues had shrunk and were full of fluid.
In Germany in the early 20th Century a doctor identified a disease when he dissected the brain of a another patient and found she had lesions (scar tissue) in certain parts of the brain; this disease became known as Alzheimer's disease, after the doctor who identified it. However, it was thought to be a rare middle-aged disease and wasn't linked to senile dementia until the 1970s and it was at this point in history that professionals in mental health realised that Alzheimer's disease is one of the main causes of death but was not being reported on death certificates.
Now, it is thought that Alzheimer's disease accounts for over 60% of all dementia cases. It is no longer considered only a disease of old age but it is recognised in younger patients too. Experts suggest that remaining mentally active, such as reading and doing puzzles can help prevent or delay the onset of this condition.