Types of Dementia
There are many different forms of dementia and each has its own causes. Alzheimer's Disease is the most common form of dementia, accounting for between 50% and 70% of all dementias.
The effects of the different types of dementia are similar, but not identical, as each one tends to affect different parts of the brain.
Here are the most common forms of dementia :
- AIDS related dementia
- Alcohol related dementia
- Alzheimer's disease, has two forms :
- Familial Alzheimer's Disease (FAD), also known as Early Onset Alzheimer's or Younger Onset Alzheimer's. See section 5.1.1.1 below.
- Sporadic Alzheimer's Disease, also known as Late Onset Alzheimer's. See section 5.1.1.2 below.
- Dementia with Lewy bodies: Another common form of dementia, sharing many similarities with Alzheimer's disease.
- Down syndrome: Research has established a link between Down syndrome and Alzheimer’s disease.
- Frontal lobe dementia, including Pick's disease.
- Vascular Dementia: The second most common cause of dementia, after Alzheimer's disease.
Some of these other types are discussed further below.
Vascular Dementia
Vascular Dementia is the second most common cause of dementia, after Alzheimer's disease. Previously, this form of dementia was known as multiinfarct dementia.
Vascular Dementia is associated with problems in the circulation of blood to the brain causing a deterioration of mental abilities as a result of multiple strokes, or infarcts, in the brain.
A stroke refers to the death of a piece of brain tissue because the blood vessels which supply it are blocked or interrupted.
These strokes may cause damage to specific areas of the brain responsible for speech or language as well as producing generalized symptoms of dementia.
Therefore Vascular Dementia may produce similar symptoms to Alzheimer’s Disease. A mixture of Alzheimer’s Disease and Vascular Dementia is a common cause of dementia, and it can sometimes be difficult to separate the two.
Parkinson’s Disease
Parkinson’s disease is a progressive disorder of the central nervous system, characterized by:
- Tremors
- Stiffness in limbs and joints
- Speech impediments
- Difficulty in initiating physical movements
Late in the course of the disease, some people may develop dementia. Drugs may improve the physical symptoms, but can have side effects which may include hallucinations, delusions, and a temporary worsening of confusion and abnormal movements.
Dementia With Lewy Bodies
A significant number of people diagnosed with dementia are found to have tiny spherical structures called Lewy bodies in the nerve cells of their brains. It is thought these may contribute to the death of brain cells.
The symptoms of this form of dementia are often mild at the outset and can be extremely variable from day to day. Common symptoms include :
- Fluctuation in the condition
- Visual hallucinations
- Extreme sensitivity to classical anti-psychotic medications leading to marked symptoms of stiffness, tremor and restriction of movement
Dementia with Lewy bodies sometimes occurs with Alzheimer’s disease and Vascular dementia.
Pick’s Disease
Pick’s Disease causes progressive and irreversible decline in a person’s abilities over a number of years. It is a rare disorder of the frontal part of the brain which can be very difficult to diagnose. The disease usually appears between 40 and 65 years of age.
Disturbances of personality, behavior and language may come before, and initially be more severe than, memory defects.
Huntington’s Disease
Huntington’s Disease is an inherited degenerative brain disorder which affects the mind and body.
Huntington’s Disease affects approximately 7 in every 100,000 people in the western world. The disease usually appears between 30 and 50 years of age.
Huntington’s Disease is characterized by intellectual decline and irregular, involuntary movement of the limbs or facial muscles. Other symptoms include:
- Personality change
- Memory disturbance
- Slurred speech
- Impaired judgment
- Psychiatric problems
There is no treatment available to stop the progression of this disease, but medication can control movement disorders and psychiatric symptoms.
Dementia occurs in the majority of Huntington’s Disease cases.
Alcohol Related Dementia: Korsakoff’s Syndrome
Too much alcohol, particularly if associated with a diet deficient in thiamine (Vitamin B1) can lead to irreversible brain damage. This dementia is preventable.
If people don’t drink, or they drink at a safe level, then they cannot develop Alcohol Related Dementia. The most vulnerable parts of the brain are those used for memory, and for planning, organizing and judgment, social skills and balance. If drinking stops drinking there may be some improvement. Taking thiamine appears to help prevent and improve the condition.
Creutzfeldt-Jacob Disease - Mad Cow Disease
Creutzfeldt-Jacob Disease is also known as Mad Cow Disease.
An extremely rare and fatal brain disorder caused by a prion, which is a protein particle. The disease occurs in one in every million people per year.
The early symptoms of this disease include:
- Failing memory
- Changes in behavior
- Lack of coordination
After which, the disease progresses rapidly, resulting in :
- Pronounced mental deterioration
- Involuntary movements appear
- Person may become blind
- Develop weakness in the arms or legs and finally lapse into a coma
This disease can jump species barriers, and can affect cows, humans, and other animals.
The Australian Red Cross (and other Red Cross organizations around the world) expressly forbid anyone who lived in the United Kingdom between the years of 1980 and 1998 to donate blood, because of the higher than average possibility that they consumed beef from slaughtered Mad Cows that entered the human food chain in the UK (in spite of promises and guarantees from numerous UK politicians). It is feared that these people will go on to develop Mad Cow Disease later in life, and if they were allowed to donate blood, that the recipients of this blood could also develop the disease.
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