If one is attuned to the differences between a dementia, which is long term and slow progressing, and a delirium, which has a quick onset and can be caused by other medical problems, often the symptoms can be reversed or prevented from creating further medical and mental damage. More than once in my practice I have been called upon when a older person suddenly is confused, feeling ill, and has a sudden personality change. For several of my fortunate clients, it turned out that a urinary tract infection was the cause of these symptoms or a medication had been causing severe side effects. The key factor is acting quickly and finding the source of the sudden change of mental status. Even if the older person is unaware of the change, is belligerent about seeing a doctor, trust your intuition if you feel that something is not right.
Sudden changes can indicate a medical emergency.
Dementia is an acquired loss of intellectual functioning. It occurs over a long period of time. There are many causes of dementia including Alzheimer's Disease, strokes, longterm alcohol abuse, a reaction to medication, Vitamin B12 deficiency, thyroid disease and depression. Symptoms and duration of dementia can be months to years. Usually speech remains normal.