Alzheimer's disease is an incurable degenerative condition and the most common of about 100 diseases that come under the umbrella of dementia (similar illnesses include vascular dementia, Lewy body disease, frontotemporal dementia and alcohol-related dementia.) What makes Alzheimer’s stand apart is that it affects 70 per cent of all people with dementia.
Alzheimer's is a progressive, mentally-disabling disease of the aged (rarely the young), which damages the nerve cells of the brain and causes a decline in the ability to process and understand knowledge. It is characterised by progressive memory loss, difficulties with problem-solving and disorientation, coordination and control over emotions, causing relentless loss of competence in recall, 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 early symptoms of Alzheimer's 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 judgment; 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.
Before last century, the disease was relatively uncommon because few people lived long enough to develop such a deterioration of the brain’s ability to function properly. Nowadays, with better health and medical interventions, older people can expect to live many more years than their forebears did, but unfortunately not without the consequences that ageing brings to the body’s organs, including the brain.
Named after German neurologist Dr Alois Alzheimer, who first recorded the disease in 1907, it was in the 1970s that Dr Robert Katzman declared that ‘senile dementia’ and Alzheimer’s were the same condition and not a normal part of ageing. Dr Alzheimer had observed changes in the brain of a deceased middle-aged woman called Auguste Deter. He discovered that the outer layer of the brain showed signs of shrinkage due to the death of brain cells This part, known as the cortex, is associated with storing memories, language and judgement. He also discovered abnormal deposits in the dead woman’s brain – plaques and neurofibrillary tangles. The latter add to the demise of brain cells by blocking the movement of nutrients. Plaques block signals from being passed between cells. 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. Proof of the condition is postmortem with the detection of amyloid plaques: hard waxy deposits consisting of tangled protein and polysaccharides that result from the degeneration of tissue. These plaques accumulate in the brains of Alzheimer's patients, gradually killing off more and more brain cells. Another theory is that toxic proteins called beta amyloids, which precipitate amyloid plaques, are the cause of the brain damage, and this toxic contamination is related in a general sense to faulty or fouled cellular hygiene ("clean-up") processes; in other words, plaques are a symptom rather than a cause of Alzheimer's.
Technical developments (2001) are now able to detect the plaques in mouse brains using harmless infrared light that penetrates deep into the tissues of the brain. This technique can detect flaws, or lesions, in the brain that are usually too small to be seen. 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%.
Studies by researchers at Erasmus University in the Netherlands have:
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.
Alzheimer's disease affects around 46.8 million people worldwide. About 50 to 70 percent of dementia cases are caused by Alzheimer’s. The disease is estimated to be the fourth biggest killer in the western world, after cancer, heart attacks and strokes. It is 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.
In 2018, an estimated 425,000 Australians have dementia, with the number projected to reach more than 1.1 million by 2056. Of those, 770,000 are likely to have a diagnosis of Alzheimer’s disease. According to Dementia Australia, Alzheimer’s disease affects three in 10 people over the age of 85.
UK estimates are that one in 20 between 70 and 80 and one in five over 80 have the condition (totalling over 700,000 people in 1995) and the number is rising as the population ages.
In 2019, India has one of the lowest incidences of Alzheimer’s on the planet. Out of 1.4 billion people, just 4 million Indians are affected by this disease. To compare, the US reports 5.8 million people with Alzheimer’s, out of its population of just 327.2 million: one in ten people over 65 and nearly one half of people over 85.
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.
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 primary sex hormones - in men, it's testosterone and in women, it's oestrogen - suppress the production of the amyloid that deposits as brain plaques. As we get older, testosterone and oestrogen fall, and that's when the amyloid starts rising.