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.
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 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.
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.
Over five million people in the USA have Alzheimer’s disease and the number continues to grow; 2001 statistics 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.
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 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.