ALZHEIMER'S DISEASE

What Is Alzheimer's Disease? Alzheimer's disease (A.D.) is a degenerative disease of the central nervous system named for the doctor who first described it. It is characterized by progressive dementia. Dementia is an impairment of intellectual function involving memory loss, mood swings, altered social behaviour and impaired daily functioning. A.D. involves the death of brain cells, wasting of nervous tissue and enlargement of the normal spaces (ventricles) within the brain. It is the most common cause of dementia. A.D. is more prevalent among women than men, and some cases run in families. The first symptoms of illness usually appear in middle age or later, and worsen over time; currently, 1 in 10 people over 65 and up to half of all people over 85 are afflicted. The prevalence of Alzheimer's disease will increase dramatically as the baby boom population reaches old age.

What Causes Alzheimer's Disease? The causes of A.D. have not been fully elucidated. When brains from individuals who have had the disease are studied after death, an almost universal finding is the occurrence of abnormal accumulations of certain protein molecules in many nerve cells; these are believed to play a key role in causing A.D., by interfering with normal brain cellular function. Much research is underway on what causes these accumulations of proteins, with the hope of preventing them from occurring. Approximately 15% of cases of A.D. tend to run in families; several genetic factors have been partially identified. Risk of developing the disease is associated with female gender, age over 60, and exposure to aluminum (e.g. in drinking water). Individuals with Down syndrome generally develop A.D. at an early age. Alzheimer's is certainly not an inevitable part of aging; many people live well into old age without such cognitive disability, and indeed it is normal to experience minor lapses in memory on occasion.

What Are The Signs And Symptoms Of Alzheimer's Disease? The first symptom of Alzheimer's disease is usually an insidious memory loss, initially for recent events, and then those more remote; in mild cases, this may be the only problem. Psychiatric and mood changes are also common in the early stages, and may comprise anxiety, depression, or hallucinations ("hearing voices" or "seeing things"). Over time, any number of other cognitive defects may develop; difficulty in recognizing people and objects, difficulty in performing complex or simple tasks, and difficulty speaking are all common problems in moderate illness. The most severely affected patients become incontinent, socially impaired, and heavily dependent on others for their daily functioning. Physical symptoms include weight loss, shuffling gait, jerking limb movements and a propensity for falls. In the latest stages, patients with A.D. may lose nearly all ability to move, speak and think.

How Is Alzheimer's Disease Diagnosed? When Alzheimer's is suspected, other possible causes of dementia must be ruled out. A solid description of the history of cognitive problems is necessary, and doctors will want to know about a family history of Alzheimer's, whether diagnosed or suspected. A test measuring mental status is likely to be administered. On physical examination, a doctor will pay particular attention to the nervous system, checking reflexes, muscle tone and movement as well as cognitive function. Referral to a neurologist is standard. Imaging of the brain may be performed by either CT scan (computed tomography, a form of x-ray) or MRI (magnetic resonance imaging). While pictures of the patient's brain may reveal disease, often symptoms of Alzheimer's disease are present long before there is visible evidence in the brain. Blood tests and samples of cerebrospinal fluid (CSF; the fluid enveloping the brain and spinal cord) are generally not useful for diagnosis, other than to rule out other illnesses (e.g. liver disease). In short, the diagnosis of Alzheimer's disease is made based on a thorough history (including a test of mental status) and physical exam, and by the exclusion of other causes of dementia.

What Are Other Causes Of Dementia? There are multiple other causes of dementia with which Alzheimer's disease can be confused. Vascular dementia (due to multiple stroke-like occurrences in various parts of the brain) is quite common, and can be difficult to distinguish from A.D.; sometimes the two conditions co-exist. Anything causing compression of brain tissue can result in dementia; whether a hematoma (an accumulation of blood inside the skull), a tumour (cancerous or benign), or a build-up of CSF. Metabolic disturbances including liver disease, vitamin B12 deficiency, and hypothyroidism (inadequate production of hormones by the thyroid) can also produce dementia. In the elderly, who are susceptible to the sedative effects of drugs, medication regimes must be examined. Also, depression can sometimes mimic A.D., especially in older people. All of these disorders must be excluded before Alzheimer's is diagnosed; thankfully, most of them can be treated much more successfully.

How Is Alzheimer's Disease Treated? Because there is no known cure for Alzheimer's disease, the goals of management are to maximize a patient's quality of life by providing symptom relief, support and education for the patient and his/her family. Some patients with A.D. are helped by "orientation cues" placed in the environment: clocks, calendars, and to-do lists, for example. As the disease progresses, supervision of daily activities may become necessary, and thought should be given to the possibility of long-term care and a living will. Medications allow improved function in some patients; first-line therapy includes cognitive enhancers called cholinesterase inhibitors, including Aricept (donepezil). Members of this class of drug can alleviate certain symptoms in mild cases, but do not alter the overall course of the disease. To treat mood and behavioural disorders, antidepressants or sedatives may be given. The roles of other drugs and compounds including estrogen, over-the-counter pain medicines, Gingko biloba, and vitamin E are currently under investigation.