Alzheimer's disease

Alzheimer's disease is a progressive, degenerative and irreversible brain disorder that causes intellectual impairment, disorientation and eventually death. There is no cure. It is estimated that 2-5% of people over 65 years of age and up to 20% of those over 85 years of age suffer from the disease. What causes Alzheimer's?
The causes of Alzheimer's disease are not yet fully understood.
There are some very rare inherited cases caused by genetic mutations, but these account for around 1% of people with Alzheimer's.
For most cases, there is a complex interaction of many genetic, environmental and life-style risk factors, with age and genetics playing the largest part.
Some factors, such as a well-balanced diet and regular physical and mental exercise can reduce the risk of developing Alzheimer's.
Protein deposits, known as amyloid plaques and tau tangles, appear and spread in the brain, particularly in the cortex and the hippocampus.
The levels of important chemical transmitters, such as acetylcholine, are reduced. Many of the blood vessels of the brain are also damaged.
These processes are made worse by chronic inflammation in the brain and by an excess of highly reactive molecules known as free radicals, which damage brain tissue.
Gradually the connections between brain cells are lost and eventually many of the cells themselves die.
It is particularly the loss of connections between brain cells that is thought to cause the devastating symptoms of the disease.
What are the symptoms?
Alzheimer's disease has a gradual onset.
Well established features of the disease include:
Problems with memory
Poor or decreased judgement
Difficulty in performing everyday tasks
Problems with language
Disorientation in time and place
Problems with abstract thinking
Change in mood and behaviour
Change in personality
Loss of initiative
The disease is often associated with depression, anxiety and sleep disturbance.
The rate of decline varies from patient to patient. The disease course runs anywhere from three to twenty years, with eight years being the average life span after diagnosis.
How is the disease diagnosed?
There is no single diagnostic test for Alzheimer's disease.
Patients require a thorough physical, psychiatric and neurological examination by a doctor when symptoms are noticed.
Doctors are able to diagnose the disease with 90% accuracy, even though proof can only be obtained by examining the brain after death.
Many other disease processes can mimic Alzheimer's such as thyroid imbalances, vitamin B12 deficiency, brain injuries, tumours, and severe depression.
Are there other types of dementia?
Yes. These include Dementia with Lewy bodies, which gets its name from tiny structures that develop inside nerve cells, and which trigger the degeneration of brain tissue.
Other rarer causes of dementia include progressive supranuclear palsy, Korsakoff's syndrome, Binswanger's disease, HIV and Creutzfeldt-Jakob disease (CJD).
People with multiple sclerosis, motor neurone disease, Parkinson's disease and Huntington's disease can also be at an increased risk.
What treatment is available?
Various types of therapy are used to try to stimulate Alzheimer's patients.
These include: psychological methods, art therapy, music therapy, playing with toys.
Some health professionals try to encourage patients to reminisce about past memories as a way to reduce depression without the use of drugs.
A variety of drug treatments have been shown to benefit patients. None are a cure, but they can temporarily relieve some of the symptoms in some patients:
Cholinesterase inhibitors including donepezil (Aricept), galantamine (Reminyl) and rivastigmine (Exelon)
NMDA receptor antagonist, namely memantine (Ebixa)
Neuroleptics, also known as anti-psychotics or major tranquillisers - although these drugs are only used as a last resort when other methods have failed
Antidepressants and anti-anxiety drugs
Is there controversy over availability of drugs?
Most certainly. The National Institute for Health and Clinical Excellence (NICE) has ruled that donepezil, rivastigmine and galantamine should only be used to treat Alzheimer's once it has progressed to its moderate stages.
Campaigners argue patients in the early stages of Alzheimer's should also have access to the drugs.
But NICE said studies showed the drugs "did not make enough of a difference".
Eisai and Pfizer, which produce donepezil, are seeking a judicial review of the decision after NICE rejected an appeal.
NICE has also ruled that memantine should be used only in clinical studies of people with moderately severe to severe Alzheimer's disease.