Of all your possessions, could there be any more precious than your memories? Unlike diseases that cause pain or loss of function, Alzheimer's disease (AD) is arguably worse, as it strips its victims of their past. Friends and family who helplessly watch the slow decline of the person they love seem to suffer almost as much. Disturbingly common, much about this disease remains a mystery.
The dementias are diseases of the brain causing memory loss, confusion, and loss of intellectual capacity. There is deterioration in emotional control, social behaviour, and motivation. Between the ages of 80 and 85, dementia affects about 1 in 6 people. Among people over 85, it affects about 1 in 3. Over half of these are caused by AD.
Risk factors and prevention
If a close family member developed AD one's risk is increased threefold. For a minority of Alzheimer's victims, an identified gene that produces a detectable protein makes them vulnerable to develop this disorder. But in most other cases we don't know the cause. Suspected causes have included environmental toxins, such as metals (remember throwing out those aluminum pans?), infections, and autoimmune reactions in which the body's immune system attacks one of its tissues.
A research study recently described in the Journal of the American Medical Association reported that older people who eat foods rich in vitamin E receive some protection from acquiring the disease. For 5 years, investigators followed 800 men and women who, at the beginning of the study when they were 65, did not have AD. At the end of the study they compared the diets and medications of those who had acquired AD during that time with those who did not. Remarkably, people who ate foods rich in vitamin E received significant protection from the disease, while those who took vitamin E supplements, but did not eat the high-vitamin-E diet, were not protected from developing AD. However, studies have shown that high doses of vitamin E can increase the risk of death. As such, people should not start on vitamin E without discussing the risks and benefits with their health care provider.
Diagnosis and pathology
There is no single test diagnostic for AD. Other causes for intellectual and memory decline, confusion, or changed behaviours must first be ruled out. Dementia caused by alcohol, clogging of blood vessels to the brain, or normal pressure hydrocephalus (increased amounts of spinal fluid accompanied by loss of brain tissue) must be considered. Depression or adverse reactions to medications can mimic dementia. Infections, heart failure, or respiratory failure all may cause confusion and disorientation.
As AD progresses, CT Scans, PET Scans, and MRIs eventually show widespread loss of brain cells, especially cells rich in the neurotransmitter, acetylcholine. Brain areas where these cells are most concentrated include the hippocampus, locus ceruleus, frontal, temporal and parietal cortex, and substantia innominata. These areas control higher executive functions and emotional responses. Brain biopsy or autopsy demonstrates characteristic accumulation of protein plaques and neurofibrillary tangles in areas of lost neurons.
Generally a disease of older people, Alzheimer's occasionally starts as early as the late 30s. First symptoms include memory lapses or momentary confusion followed by periods of apparently normal cognitive function. As the episodes become longer and more frequent, complex but routine behaviours, such as driving the car, become more difficult. The person will sometimes do bizarre things, like putting perishable food away in a cupboard or placing writing materials in the refrigerator. As cognitive decline continues, they become unable to care for themselves. They will often feel restlessness, confusion, and even paranoia. Not remembering that they moved an article, when they later are unable to find it, they become convinced intruders have come in and taken it.
Death occurs in 8 to 20 years, often due to pneumonia as the parts of the brain that control respiration and protective airway reflexes become i