Alzheimer's disease is an incurable degenerative condition. It is a mentally disabling disease of the aged (rarely the young) which attacks the nerve cells of the brain and impairs a person's memory, coordination and control over emotions, causing relentless loss of competence in memory, speech and thought/perception patterns and an increase in feelings of disorientation. Profound dementia and death follow, usually within two to five years of diagnosis.
Typical symptoms are lapses of short-term memory, like forgetting a phone call five minutes later and placing items in inappropriate places; inability to carry out simple mechanical tasks, like tying shoe laces and other familiar tasks; personality and mood changes, such as becoming more aggressive or depressed; disorientation to time and place; problems with abstract thinking; poor or decreased judgement; and loss of initiative. Eventually, most people with Alzheimer's disease become unable to care for themselves. One of the most difficult aspects of caring for a spouse with advanced Alzheimer's is living with the idea that the man or woman you have loved, fed and cared for no longer recognizes you.
The disease was first observed in 1907 by the German neurologist, Alois Alzheimer. It is now believed that Alzheimer's disease proceeds by damage to the hippocampus, a part of the brain essential for learning and memory. The entorhinal cortex is the first area of the hippocampus to be damaged.
There is no simple test for Alzheimer's disease. Brain scans can pick it up in the early stages, but are considered too expensive or traumatic for general use. The only proof of the condition is at the postmortem and the detection of amyloid plaques (hard waxy deposits consisting of tangled protein and polysaccharides that result from the degeneration of tissue). These plaques collect in the brains of Alzheimer's patients, gradually killing off more and more brain cells. Another theory is that the toxic proteins, called beta amyloids and which precipitate the deposit of amyloid plaques, do the brain damage, and that this is related in a general sense to faulty or fouled cellular hygiene ("clean-up") processes.
Latest technical developments (2001) are now able to detect the plaques in mice brains using infrared light which penetrates deep into the tissues of the brain without causing any harm. More importantly, this technique can detect flaws, or lesions, in the brain that are usually too small to be seen. The multi-photon microscope that delivers the infrared light is not currently able to penetrate through the thickness of the human skull. Researchers have also had success with clearing plaques from the mice brains with vaccinations of antibodies.
A gene for familial Alzheimer's was announced in 1993. By 1994, the test for the gene (ApoE) was estimated to predict, with 90% accuracy, whether an individual would succumb to Alzheimer's disease by age 65. It is estimated that between 2 and 3% of the population -- around one million people -- carry the E4 version of the ApoE gene, associated with lower life expectancy and Alzheimer's disease. Among people who have one copy of the E4 gene, 45% have the disease by the age of 75. Among those with two copies, this rises to 90%.
More than 4,000 Alzheimer's patients around the world are participating in trials to find a way to prevent or slow the progression of the disease and millions to billions of dollars are being expended.
The disease is estimated to be the fourth biggest killer in the western world, after cancer, heart attacks and strokes. The incidence seems to be rising. It was estimated that between one person in 50 who are aged 65-70 is affected, rising to one in 25 of those aged 70-80, and one in five aged 80 and over. 2001 statistics from the USA suggest the frequency is as high as one in ten people over 65 and nearly one half of people over 85. UK estimates are that one in 20 between 70 and 80 and one in five over 80 have the condition (totaling over 700,000 people in 1995) and the number is rising as the population ages.
In the USA, the cost of caring for the approximate 4 million people with Alzheimer's in 2001 was estimated to be $80 billion - more than 1% of the gross national product - of which the federal government spends some $50 million directly on research. The number of sufferers is expected to increase to 5.5 million by 2010, (implying a rise in federal spending to more than $82 million) and to 14 million people by 2050.
Studies by researchers at Erasmus University in the Netherlands have: (1) established a strong link between smoking cigarettes and the risk of developing Alzheimer's disease and other forms of dementia in both men and women and (2) found that women with the longest reproductive period - over 39 years - were at a higher risk of dementia or Alzheimer's disease than those with the shortest period - less than 34 years. For every extra year that women retained their reproductive capacity, their risk of Alzheimer's disease increased 3%, but that the risk seemed to be limited to women who had a genetic susceptibility to Alzheimer's disease because they carried a gene known as ApoE-e4.
A US study, published in the Proceedings of the National Academy of Sciences, suggested that people who were relatively inactive had a 250% increased risk of developing Alzheimer's. It surveyed the carers of 193 Alzheimer's patients and 358 of their healthy friends, neighbours and acquaintances, and quizzed them about their different hobbies in middle-age. It found those with Alzheimer's were less likely to have had intellectual hobbies, and were unlikely to have had as wide a range of interests as their healthy peers.
A French study showed that consumption of 3 to 4 glasses of wine a day reduces the likelihood of developing Alzheimer's disease by 75%. The wine industry was not involved in the study.
Most people don't think of dementia as a deadly condition, but as time goes on patients have difficulty swallowing, they may have difficulties walking and they become more susceptible to malnutrition and to infections.