Dementia refers to a group of symptoms that affect thought processes and social interactions severely enough to interfere with normal activities. Common symptoms include memory loss, change in personality and difficulty with communication, learning or planning. Some types of dementia steadily worsen with time and are classified as progressive dementias; although these forms are typically associated with old age, they are not a normal part of aging. Other types of dementia can be reversed.
Alzheimer's Disease
According to the Mayo Clinic, Alzheimer's disease is the most common form of dementia in people older than 65. The Merck Manual states that the disease affects twice as many women as men. In Alzheimer's disease, clumps and tangles of proteins destroy brain cells gradually over time, causing loss of short-term memory and, eventually, longer-term memory. More severe symptoms include lapses of judgment, extreme confusion and irritability, and loss of vocabulary and abstract thinking. Alzheimer's usually progresses slowly.
Vascular Dementia
Vascular dementia occurs when the blood vessels serving the brain sustain damage, such as from a heart attack or stroke. The damage can sometimes be completely reversed; in other cases, symptoms worsen over time. The symptoms depend on the location and degree of damage, but common symptoms include confusion, memory loss and behavioral changes. This is the second most common type of dementia in older patients, and it affects more men than women.
Lewy Body Dementia
This form of progressive dementia has many features in common with Alzheimer's disease, including the presence of protein clumps (called Lewy bodies) in the brain and many of the same defects in thought processes. Several signs differentiate the two conditions, however. Unlike Alzheimer's victims, people with Lewy body dementia struggle less with short-term memory and more with remaining alert and attentive. They typically fluctuate between good days on total lucidity, and very bad days with marked symptoms. About 80 percent of patients experience hallucinations (usually visual). Early in the course of Lewy body dementia, many patients have muscle tremors similar to Parkinson's disease. Twice as many men as women have Lewy body dementia, and it is the third most common form of the condition.
Frontotemporal Dementia
As the name implies, frontotemporal dementia involves damage to the nerves in the frontal and temporal lobes of the brain, also known as the areas that control language and personality. In addition to memory and processing problems, these patients often display marked personality changes and inappropriate behaviors. Frontotemporal dementia starts between the ages of 40 to 65, earlier than the typical onset of Alzheimer's disease. In many cases, the cause is unknown. Up to 10 percent of dementia cases are frontotemporal dementia.
Reversible Forms
Dementia resulting from problems with a person's metabolism, immune system or cardiovascular system can be reversed by curing the underlying cause. Dementia as a result of Vitamin B deficiency and certain poisons and medications can be reversed as well.
