No one really knows what Alzheimer disease is. Billions of dollars are being spent to find a cure for an illness that still can’t be diagnosed with certainty. But an AD diagnosis is easily given to elderly people having memory problems. Fear and stigmatisation are the result.
Alzheimer disease is het most well-known cause of dementia. Dementia isn’t an illness by itself. It is a cluster of behavioural symptoms and is caused by underlying processes. Over fifty causes and diseases have been indicted for generating dementia, among which are for instance stroke, Parkinson disease, alcoholism, infections such as AIDS and syphilis, brain tumours, toxic exposure, head injury, and vitamin B12 deficiency. Most types of dementia start a chain reaction of irrevocable decline. No cure exists yet, although there are treatments that could ease certain symptoms.
As for Alzheimer’s, obscurity still surrounds the disease named after the German psychiatrist Alois Alzheimer, the first one to describe the symptoms of the disease at the beginning of the last century. It is even hard to determine whether someone suffers Alzheimer disease. No test is available yet to definitely establish the diagnosis. And not even brain biopsy after death can give an unambiguous answer. The diagnosis AD is given after all kinds of tests and examinations have excluded other types of dementia. Based on the presence of specific waste products in the cerebrospinal fluid drained via a spinal tap, specialists today can make a fairly accurate prediction.
The causes of AD remain a mystery. In about ten percent of patients, the disease is clearly linked to a genetic deficiency. In the rest no identifiable genetic component has been found yet. Dietary and other environmental risk factors related to culture seem to influence the incidence of the disease. Alzheimer’s is more common in Europe and the United States, whereas people in Asia suffer more from vascular dementia, caused by strokes.
The risk of contracting Alzheimer disease increases with age, but it is not a part of normal ageing. The hippocampus, a brain part involved in memory function, is vulnerable even in the normal ageing process and is certainly the first victim of AD. With the progression of AD, the hippocampus becomes smaller, hence the memory problems. People with thicker hippocampi develop dementia to a lesser extent. Possibly they have a cognitive reserve to compensate for neuropathological changes. It is not clear yet whether this reserve capacity was present at birth or is acquired during life through cognitive stimulation. Low education and a monotonous job seem to be a risk factor for Alzheimer’s.
Cells in the hippocampus that die, don’t send signals anymore to their connections in other brain regions. Gradually, they will die too affecting again other cells that will be deprived of their input as well. This is the chain reaction that brings about the process of degeneration characteristic of Alzheimer disease. It involves progressively worsening memory, language and visuospatial skills, and changes in personality. This process may take from ten to twelve years and will lead to the death of the patient.
The most characteristic physical signs of AD in the brain are tangles and senile plaques. Tangles are knots of protein fibres within neurones and senile plaques are clumps of insoluble protein between neurones. It is not known yet why these tangles and plaques appear. For one reason or another, the production of the proteins concerned goes awry.
Also in the brains of elderly people who didn’t suffer dementia when they died, some tangles and plaques are present only far less than in the brains of Alzheimer’s patients. The plaques and tangles first occur in the brain area where the hippocampus is also situated. They are to blame for the disruption of the connections to memory systems.
Alzheimer disease is one of the most intensively researched diseases of recent date. Very little is known yet about the relationship between this disease and our genes. In a small number of cases of AD, a hereditary factor is obvious since the disease runs in families. In these cases, people are often stricken by the disease well before they turn 65 years of age. This type of AD is indicated as early-onset Alzheimer disease. Mutations in a few genes have already been found that contribute to early-onset Alzheimer’s.
The more common type of Alzheimer disease that presents itself at later age, in most cases cannot directly be linked to hereditary factors within a family. But its cause may still lie in gene variants. In years to come, surely genes will be discovered that play a part in the development of AD or that, on the contrary, offer protection against the disease. But although cautious preliminary conclusions have been drawn about genetic influence on the development of Alzheimer’s, no doubt exists of course that these genes first have to be activated before the degeneration process starts that finally will result in Alzheimer disease. Environmental factors, like diet, living conditions, and lifestyle, will most certainly turn out to play a part of utmost importance.
But a growing number of voices emerge from the scientific community questioning the existence of Alzheimer disease. They say Alzheimer’s is just a label for brain ageing. Since brain ageing is caused by a complex mix of genetic, environmental, and behavioural factors, the variety of signs and symptoms is tremendous. This makes the brain ageing process so unique. Even with the label Alzheimer disease, no two illness courses are the same.
“Every time the diagnosis of Alzheimer’s is made, we must remember that it can be as socially destructive as it is scientifically uncertain.”
Peter J. Whitehouse, professor of neurology
“Alzheimer’s is a multibillion-dollar industry”, states neurologist Peter Whitehouse in the book The Myth of Alzheimer that he wrote together with Daniel George. The label is driven in large part by the pharmaceutical industry and some academic experts, according to Whitehouse. And despite billions of dollars spent on research no molecular event has been found that differentiates AD from ageing.
“Should biomedical disease labels with frightening cultural meanings be used to describe a condition that might otherwise be considered variable human brain ageing?”, asks Whitehouse. The story of the disease can become self-fulfilling and exacerbate an already challenging situation. “Every time you hear the word Alzheimer’s, it affects your brain.”
To cure Alzheimer disease would be to arrest the natural process of brain ageing, which would be very unlikely. “Brain ageing is not something that can be cured. We are giving people false hope.”
In stead of spending so much money on finding a cure for Alzheimer’s, the emphasis should be on prevention and care. Whitehouse: “We must change our thought process about brain-ageing. De-emphasise the role of medication and focus on non-medical, humanistic interventions to promote quality of life.”
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