Types of Dementia

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Alzheimer’s Disease

Alzheimer's Disease is responsible for more than 50% of dementia cases in the elderly. This form of dementia causes the nerve cells in the memory centers of the brain to die. Alzheimer's has also been found to be associated with a characteristic tangling of fibers within nerve cells and a build up of A-beta-amyloid (a kind of protein) 'plaques' in the brain. The extensive build up of these tangles and plaques may gradually damage the ability to remember, think, speak, learn and make decisions.

Alzheimer's usually affects people older than 60 years of age although the disease has been known to affect people in their 40s. There is no way to diagnose how quickly the disease will progress. Severe Alzheimer's may take from 2 to 20 years to develop. Complicating the diagnosis of Alzheimer's is the fact that its
early symptoms - forgetfulness and lack of concentration - resemble the natural signs of aging.

Alzheimer's commonly starts with memory lapses, mood swings and difficulty with finding the right words. As the disease progresses the individual will become even more confused and find it increasingly harder to understand what others are saying to them. They will find it difficult to bathe, clothe and feed themselves. In the late, severe stages of Alzheimer's, they may lose control of their urinary and bowel functions, become unable to talk and grow less and less able to move without help. People with Alzheimer's will likely become dependent on a caregiver and eventually need 24 hour support.

Causes of Alzheimer's Disease

It is not known exactly what causes Alzheimer's disease.  Currently accepted wisdom about risk factors for the disease includes the following:

  • A genetic disposition may be involved - researchers have identified 4 distinct genes that seem to influence the development of Alzheimer's.  A positive family history of Alzheimer's disease increases the risk of developing the disease.
  • Damage to the brain from head trauma that causes concussion may make Alzheimer's more likely.  This is probably only a minor risk factor.
  • Environment factors - aluminum, mercury and viral infections have all over the years been suggested as causes of Alzheimer's.  None of these factors has been shown to be related to the disease.
  • Postmenopausal hormone replacement in women may reduce the likelihood of Alzheimer's, though this is yet to be confirmed.
  • Individuals affected with Down syndrome are more likely to get an early form of Alzheimer's (between the ages of 40 and 60)

Symptoms of Alzheimer’s Disease

Alzheimer's is often diagnosed much later than it appears because family and friends mistake the early symptoms of Alzheimer's as signs of depression or general aging. For example, memory loss or 'forgetting things' is a symptom of Alzheimer's but it is also commonly accepted as a sign of getting older. When forgetfulness
begins to impair productive daily functioning, advice should be sought.

If you notice the following behaviors in your care recipient, please notify a medical professional:

  • Memory loss that seriously impairs your care recipient's ability to function on a day-to-day basis
  • Difficulty in performing routine activities (i.e., doing the laundry, cooking, cleaning)
  • Difficulty remembering or using correct/appropriate language
  • Inability to perceive time or place clearly (e.g., forgetting completely where they are and what they're doing)
  • Loss of judgment (e.g., wearing inappropriate clothing for the season or occasion)
  • Inability to think abstractly (e.g., not understanding what money is or what it's for)
  • Misplacing objects (e.g., putting a blanket in the bathtub or brush in the microwave)
  • Sudden changes in mood and manner, for no obvious reason
  • Personality changes resulting in, among other things, confusion, inappropriate behavior, suspiciousness or fearfulness
  • General apathy

Types of Alzheimer’s Disease

There are currently 2 known types of Alzheimer's Disease:

Sporadic Alzheimer's Disease: Sporadic Alzheimer's is the most common type of the disease (between 90 - 95% of those affected). While external causes may be responsible for this type of the disease, scientists haven't ruled out potential genetic connections to Sporadic Alzheimer's, either.

Familial (Autosomal Dominant) Alzheimer's Disease: Familial Alzheimer's is less common than sporadic Alzheimer's (5 - 10% of those affected). This type of the disease is passed on through dominant inheritance meaning that if one of your parents has a particular gene (i.e., that may be responsible for Alzheimer's), you will have up to a 50% chance of getting the disease. A history of dementia in the family over several generations is a strong indicator of this type of Alzheimer's. If a particular gene is linked to Alzheimer's disease in a family, relatives may have the option of undergoing testing for that gene to determine their own risk of developing the disease. 

Treatment for Alzheimer’s Disease

Management can be extremely difficult. At this time there are no known cures for Alzheimer's Disease. Treatment generally focuses on quality of life issues, alleviating symptoms in the mild to moderate stages of the disease and providing institutional care when home care ceases to be feasible.

Acetylcholinesterase inhibitors are one class of drugs used to treat Alzheimer's. These drugs regulate the brain's production of acetylcholinesterase, a body chemical that breaks down acetylcholine, another chemical that is needed for the transmission of nerve impulses. People with Alzheimer's usually have low levels of acetycholine. The acetylcholinesterase inhibiting drugs include donepezil and tacrine. Studies have shown that these drugs can improve functioning in mild to moderate disease, though they do not seem to have value in the advanced stages.  Tacrine can adversely affect the liver, so your physician may advise regular blood tests when using this medicine.

Some other acetylcholinesterase inhibitors now being studied include:

  • Rivastigmine
  • Metrifonate
  • Galanthamine

Side effects associated with these drugs include:

  • Diarrhea
  • Loss of appetite
  • Nausea/vomiting
  • Muscle cramping

Unfortunately, the anticholinesterase inhibitors seem to have an effect only in Alzheimer's Disease and are not used for other causes of dementia.

Your care recipient may not be able to communicate information about any symptoms he or she is experiencing.  Whenever possible, caregivers should be aware of the possibility of drug side-effects (as well as viral infections and other illnesses that may affect the care recipient).  If your care recipient seems to be suffering physical distress, you should consult your physician.

Estrogen: As mentioned above, studies have found that women who are on estrogen (hormone) replacement therapy following menopause may have a lower
risk of getting Alzheimer's. There are as yet no direct studies that indicate that estrogen treatments are helpful to people who already have Alzheimer's.

Non-steroidal anti-inflammatory drugs (NSAIDs): These drugs such as aspirin and ibuprofen are commonly used for arthritis. There seems to be some evidence that long-term use of these drugs prevents decline of cognitive (understanding, problem-solving) abilities. The results of continuing research in this area are awaited.

Anti-oxidants: One clinical study found that taking 2,000 units of alpha tocophenol - a form of vitamin E - on a daily basis was as effective as donepezil in delaying the progression of moderate Alzheimer's. Vitamin E has few side effects.

Ginkgo biloba extract: Clinical studies have found that taking 120 - 240 mg of ginkgo biloba extract daily can produce a modestly positive effect in the Alzheimer's care recipient with minimal side effects. Ginkgo biloba is a blood-thinning agent that may exacerbate some side effects of other medications the care recipient may be taking - seek medical advice before using this drug.

Alzheimer's Disease Resources

- Alzheimer's Association (US)
- Alzheimer's Foundation of America (US)
- Alzheimer's Disease (NIH PubMed Health)
- Neuroscience for Kids from Washington University