What is dementia?

Dementia is a general term used to describe a decline in mental function that is severe enough to interfere with daily living. Dementia is not a specific disease. It is a group of symptoms that can affect thinking, memory, reasoning, personality, mood and behavior.

Dementia develops when the parts of the brain that are involved with learning, memory, decision-making, and language are affected by any of various infections or diseases. The most common cause of dementia is Alzheimer's disease. However, there are numerous other known causes of dementia, such as vascular dementia, dementia with Lewy bodies, and dementia due to Parkinson’s disease and others. The condition of dementia is not a normal part of aging.

One common misbelief about memory loss is that it always means a person has dementia. There are many causes of memory loss. Memory loss alone doesn’t necessarily confirm a diagnosis of dementia. It’s also true that some memory loss is normal as a person ages (some neurons in the brain naturally die as we age). However, this type of memory loss is not disabling.

Who gets dementia?

Dementia is considered a late-life disease because it tends to develop mostly in elderly people. About five to eight percent of all people over the age of 65 have some form of dementia, and this number doubles every five years above that age. It is estimated that as many as half of people 85 or older have dementia.

What are the types of dementia?

Dementias are often broken down into two main categories -- Alzheimer type or non-Alzheimer type. Dementias of the Alzheimer’s disease type are defined by the symptoms of memory loss plus impairment in other brain functions, such as language function (aphasia); inability to move the muscles associated with speech (lips tongue and jaw; apraxia); or perception, visual or other inabilities to recognize speech or name objects (agnosias).

Non-Alzheimer dementias include the frontotemporal lobar degenerations, which are further broken down into two main types. One type primarily affects speech. An example is primary progressive aphasia syndromes. The other type is defined by changes in behavior, including lack of feeling, emotion, interest or concern (apathy); loss of a “social filter” (disinhibition); personality change and loss of executive functions (such as the ability to organize and plan ahead). In both of these frontotemporal lobe dementias, memory loss is relatively mild until later in the course of the disease.

Other non-Alzheimer’s disease dementias include vascular disorders (multiple strokes), dementia with Lewy bodies, Parkinson's dementia, and normal pressure hydrocephalus.

What causes dementia?

Dementia is caused by damage to the brain. There are many causes of dementia. The causes of dementia can be generally grouped as follows:

  • Degenerative neurological disorders, such as Alzheimer's disease, frontotemporal lobar dementia, dementia with Lewy bodies, Parkinson's disease dementia and Huntington's disease
  • Vascular disorders, such as multi-infarct dementia, which is caused by multiple strokes in the brain
  • Infections that affect the central nervous system, such as HIV dementia complex and Creutzfeldt-Jakob disease, a quickly worsening and fatal disease that is recognized by its symptoms of dementia and muscle twitching and spasm (myoclonus)
  • Long term drug or alcohol use
  • Depression
  • Certain types of hydrocephalus, a buildup of fluid within the brain that can result from developmental abnormalities, infections, injury, or brain tumors

Alzheimer's disease accounts for 50 percent to 70 percent of all dementias. However, many patients with Alzheimer's disease also have damage from other vascular brain disease, such as from mini strokes. Patients with more than one brain condition present that cause dementia are considered to have "mixed" dementia. Frontotemporal lobar degenerations, of which there are several types, account for a substantial number of dementias, especially among people in their 50s and 60s. Dementia with Lewy bodies has also been diagnosed with increasing frequency in recent years. These patients have clinical signs of Parkinsonism as well as dementia, though the connection between dementia and Parkinson's disease is still not completely understood.

What are the symptoms of dementia?

Early symptoms of dementia include :

  • Forgetting recent events or information
  • Repeating comments or questions over a very short period of time
  • Misplacing commonly used items or placing them in usual spots
  • Not knowing the date or time
  • Having difficulty coming up with the right words
  • Experiencing a change in mood, behavior or interests

Signs that dementia is getting worse include:

  • Ability to remember and make decisions further declines
  • Talking and finding the right words becomes more difficult
  • Daily complex tasks, such as brushing teeth, making a cup of coffee, working a tv remote, cooking, and paying bills become more challenging
  • Rational thinking and behavior and ability to problem solve lessen
  • Sleeping pattern change
  • Anxiety, frustration, confusion, agitation, suspiciousness, sadness and/or depression increase
  • More help with activities of daily living – grooming, toileting, bathing, eating – is needed
  • Hallucinations (seeing people or objects that aren’t there) may develop

The symptoms mentioned above are general symptoms of dementia. Each person diagnosed with dementia has different symptoms, depending on what area of the brain is damaged. Additional symptoms and/or unique symptoms occur with specific types of dementia.

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