Alzheimer's Disease

What is Alzheimer's Disease ?

Alzheimer's disease is a progressive degenerative disorder of the cerebral cortex (especially the frontal lobe) that accounts for more than half of all cases of dementia. An estimated 5% of people over age 65 have a severe form of this disease, and 12% suffer from mild to moderate dementia. Because this is a primary progressive dementia, the prognosis for a patient with this disease is poor.

Causes of Alzheimer's Disease

The cause of Alzheimer's disease is unknown, but several factors are thought to be closely connected to this disease. These include neurochemical factors, such as deficiencies of the neurotransmitters acetylcholine, somatostatin, substance P, and norepinephrine; environmental factors, such as aluminum and manganese; trauma; genetic factors; and viral factors such as slow-growing central nervous system viruses.

Researchers believe that up to 70% of Alzheimer's cases stem from a genetic abnormality. Recently, they located the abnormality on chromosome 21. They've also isolated a genetic substance (amyloid) that causes brain damage typical of Alzheimer's disease. The brain tissue of patients with this dementia has three distinguishing features: neurofibrillary tangles, neuritic plaques, and granulovascular degeneration.

Signs & Symptoms of Alzheimer's Disease

Early symptoms, such as memory loss, may be attributed to the forgetfulness associated with ageing. Gradually, the loss of cognitive function disrupts the patient's ability to perform common daily activities, such as paying bills, driving, and housekeeping. Some people remain unaware of their symptoms, while others are painfully aware of the fact that they are losing mental function.

Symptoms of Alzheimer's disease include the following:

• Apraxia (inability to perform physical tasks such as dressing, eating)
• Aphasia (loss of ability in comprehension of spoken or written language)
• Delusions
• Easily lost and confused
• Inability to learn new mental tasks
• Loss of judgment, reason, and cognitive abilities
• Loss of inhibitions and belligerence
• Social withdrawal
• Visual hallucinations

Diagnostic Tests

Alzheimer's disease is diagnosed by exclusion. Various tests such as those described below are performed to rule out other disorders. The diagnosis can't be confirmed until death, when pathologic findings come to light at autopsy.

Position emission tomography measures the metabolic activity of the cerebral cortex and may help confirm early diagnosis.

EEG allows evaluation of the brain's electrical activity and may show slowing of the brain waves in the late stages of the disease. This diagnostic test also helps identify tumors, abscesses, and other intracraniallesions that might cause the patient's symptoms.

Cerebrospinal fluid analysis may help determine if the patient's signs and symptoms stem from a chronic neurologic infection. Cerebral blood flow studies may detect abnormalities in blood flow to the brain.

Treatment

No cure or definitive treatment exists for Alzheimer's disease. Therapy consists of cerebral vasodilators, such as ergoloid mesylates, isoxsuprine, and cyclandelate ro enhance the brain's circulation; hyperbaric oxygen ro increase oxygenation to the brain; psychostimularors such as methylphenidate to enhance the patient's mood; and antidepressants if depression seems to exacerbate the patient's dementia.

Most other drug therapies being tried are experimental. These include choline salts, lecithin, physostigmine, enkephalins, and naloxone, which may slow the disease process. Drugs commonly given to enhance cognition include thorine hydrochloride with ariceptdonepezil hydrochloride (Cognex).

Prevention Tips

Because the cause of the disease is unknown, there are no prevention protocols to follow at this time. And, because the controllable risk factors for Alzheimer's disease are unknown, it is not yet possible to reduce the chances of developing the disease.