Alzheimer's disease was first described by Alois Alzheimer in 1906. He observed a progressive loss of memory and personality in a woman in her fifties; many years earlier than is normal to observe these symptoms in a woman her age, symptoms which usually result from senile dementia. On post-mortem examination, he noticed strange defects in the woman's brain. These were of two types; 'amyloid plaques' which are starch-like tangles of protein (beta amyloid) within the brain; and 'neurofibrillary tangles', which are tangles of proteins (tau protein) within the brain cells. Around these two types of tangles, brain cells had been destroyed. The brain itself was smaller than usual, and certain areas of it seemed to have degenerated specifically. Little advance was made on Alzheimer's disease until the 1980s. Until this day, the only way to differentiate Alzheimer's disease from other types of senile dementia is by these characteristic marks, only identifiable post-mortem.
What is Alzheimer's?
Alzheimer's disease is a progressive senile dementia. What does this mean? Basically, dementia is defined as a global impairment of intellect, personality and memory without impairment of consciousness ie, the Alzheimer's victims do not lapse into coma, or suffer any similar problems. The characteristics of the disease are a progressive loss of short-term memory, followed by long-term memory, personality, ability to interact socially and speech impairment. Balance is not strongly affected (as it is in CJD 1 and some other neurodegenerative diseases), neither is the ability to learn new skills. These characteristics are due to the way that specific areas of the brain start to degenerate in a specific order. The symptoms are severe and distressing. At the time of writing, ex-US president Ronald Reagan has Alzheimer's disease. He can no longer remember that he used to be the President and is incapable of caring for himself or conducting a coherent conversation. It is frightening to see somebody who used to be the most powerful man in the world reduced to this.
Types of Alzheimer's Disease
There are two types of Alzheimer's disease: sporadic and familial. Familial Alzheimer's disease is directly inherited in families, and is a result of one of many genetic mutations. This form of the disease usually strikes victims in their sixties, but can manifest itself in the early fifties. This type of Alzheimer's is particularly aggressive, and there is no proven affective therapy or preventative measures that can be taken.
Sporadic Alzheimer's accounts for the vast majority of cases, and is the most prevalent senile dementia. It is indiscriminate of race and gender, and appears to arise spontaneously in the brains of many people over the age of seventy. The likelihood of having it increases with age. It may be that if we all lived until 130, we would all eventually get it.
What causes this disease? Unfortunately, the jury is still out on that one. There have been thousands of studies carried out and even more papers written, but still we are not seeing the truth. Most familial Alzheimer's is caused by a mutation in one of the Presenillin genes. The involvement of these genes in the formation of the characteristic 'plaques' and 'tangles' is not fully understood. Both the types of tangles appear to cause cell death in laboratory conditions, but it is not known whether this is the case in living brains. There is a lot of controversy in the scientific community as to whether these tangles cause the cell death and neurodegeneration, or whether they are simply the result of it. The two prime candidates for causing the degeneration are the two proteins that cause the tangles, tau and beta amyloid. At the moment, it seems that tau is more likely to be the cause (at least in sporadic Alzheimer's), but this may have changed tomorrow.
And now the useful bit. What can you do about it? Well, thankfully you can do quite a lot. All the following is based in clinical evidence, and is not just hearsay:
Exercise, stay physically active. This increases the blood flow to the brain, which prevents the initiation of the catastrophic events that results in the disease.
Stay mentally active. Reading books, doing the gardening, interacting socially with people, even just thinking. All these things strengthen the links between nerve cells in the brain, and there is increasing evidence that loss of such connections may be an initiating factor in the disease.
Have low cholesterol ie, don't smoke and don't drink to excess. Exercise.
High blood pressure is bad so low sodium diets are good.
Vitamin E seems to limit the damage (but is dangerous in overdose).
Basically, take care of your body. And most importantly use your brain. Like your body, you either use it or lose it!