About Alzheimer's Disease

About Alzheimer's Disease
Alzheimer's disease leads to nerve cell death and tissue loss throughout the brain. Over time, the brain shrinks dramatically, affecting nearly all its functions.

The microscopic changes that occur in the brain of a person with AD were first noted by German neurologist Alois Alzheimer in 1906. He performed an autopsy on a woman who had become more and more confused in the years preceding her death. He called the changes he observed in her brain plaques and tangles. These features can only be seen upon autopsy. Tangles and plaques interfere with neuronal functions, such as communicating with each other and sending messages to other parts of the body.

Research suggests that the formation of tangles in the brain may be a part of the normal aging process. Dr. John Morris of Washington University School of Medicine in St. Louis, Missouri, published a report titled "Tangles and plaques in nondemented aging and preclinical Alzheimer's disease" in the March 1999 issue of Annals of Neurology. This study showed that of the 39 nondemented people (people with no behavioral evidence of Alzheimer's disease), all had tangles in their brains. So perhaps developing tangles is an inevitable part of growing old. "This is further evidence that there is such a thing as truly healthy aging and that Alzheimer's disease is not inevitable," states Morris. More research is needed to figure out what role tangles and plaques play in AD. Are only plaques responsible, or do tangles and plaques interact?

Other observed changes in the brain affected by AD include:
-neuronal degeneration in a part of the brain called the nucleus basalis of Meynert.
-decreased brain levels of the neurotransmitter acetylcholine.

What are tangles?
It is unclear how neurofibrillary tangles (NFT) form. NFTs are found inside of the neuron: the neurons themselves become deformed and clump together. NFTs have been described as looking like a rope tied in knots. A protein named tau has been shown to be involved in forming NFTs, but more research is needed to solve the mystery of how and why NFTs form, and how exactly they affect the brain.

What are plaques?
Unlike tangles, plaques occur outside the neuron. Plaques are mainly composed of a protein called beta amyloid, although other proteins contribute to plaque formation. Research has shown that a protein in our bodies called amyloid plays a significant role in AD. Proteins are vital molecules that control all sorts of processes in our body. The amyloid protein occurs naturally in our brains, but as we age, too much of it (in a form called beta amyloid) accumulates in the brain, forming plaques. Beta amyloid is formed when an enzyme clips the amyloid precursor protein; beta amyloid, a fragment from this process then aggregates in deposits. It is unknown whether these deposits are due to excess production or whether the enzymes that usually break it down are not functioning properly. This situation is similar that of cholesterol in our bodies. Some cholesterol is needed to keep our cells healthy, but too much cholesterol can block arteries and lead to heart attacks and other problems.

What Can You Do to Protect Your Brain As You Age?

As you age, some connections in your brain may fail due to tangles or plaques, so it makes sense that the more neural connections you have overall, the more you will be able to compensate for the damaged connections. It's like a sports team. If one player gets injured and there is a qualified player on the bench who can substitute, the team will still function well. The more players available to play for injured team members, the better the team will fare.
How do you get and maintain neural connections? It is thought that staying active, both mentally and physically, will help. Challenge your mind. Remember people's names. Work crossword puzzles. Do math. Read. Learn new words.

Know more about AD and watch a brain tour:
http://www.alz.org/braintour/3_main_parts.asp

References for AD:
http://en.wikipedia.org/wiki/Alzheimer's_disease
http://www.medicalnewstoday.com/articles/159442.php
http://www.nlm.nih.gov/medlineplus/alzheimersdisease.html

References for NFT's & amyloid plaques:
http://www.brightfocus.org/alzheimers/about/understanding/plaques-and-tangles.html

Image credit:US Alzheimer Organisation