Neurological Disorders

Contents:

• Introduction
• Alzheimer's Disease
• Parkinson's Disease
• Incidence of Leading Neurological Disorders

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Introduction

Thanks to advances in biomedical research, the average age of our population has been increasing. Today, the average human life expectancy is 70 years. Unfortunately, increased life expectancy has brought with it a number of diseases, particularly neurological diseases, which strike mainly in the middle and later years of life. Among these are Alzheimer's and Parkinson's diseases.

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Alzheimer's Disease

One of the most debilitating of these neurological diseases is Alzheimer's, discovered by Dr. Alois Alzheimer in Germany, in 1906. Alzheimer's disease is a degenerative disease that attacks the brain. Slowly, it kills the brain cells, until the brain can no longer send messages properly to other parts of the body, or to each other. The symptoms of Alzheimer's are generally characterized by progressive loss of memory and language skills, disorientation, personality change and dementia. Tragically, the disease culminates in the childlike helplessness of its victims and eventually causes their death. The progressive degradation of this disease is endured not only by the patient, but also by his or her family and, oftentimes, an entire community.

According to a recent study, an estimated 300,000 adults in Canada and 4 million adults in the United States suffer from this disease, which severely debilitates more than 125,000 of them each year. Alzheimer's disease is the leading cause of hospitalization of the elderly, afflicting 10% of people over the age of 65 and almost 50% of those over 85. Alzheimer's disease often appears in families, making a genetic cause for the disease suspect.

Studies of the human brain continue to give important information to researchers on the total effect of the disease in its final stages. However, this work can only be done after the patient is deceased. Alzheimer's disease needs to be looked at during its development to find clues to its origin and how it progresses. Such information is vital if physicians are to improve diagnosis and treatment.

Researchers are now developing several diagnostic tests for Alzheimer's disease. While still experimental, these tests hold much promise.

Aging monkeys and cats with some signs and symptoms of human senility are being studied as partial models. More recently, a mouse strain has been developed which serves as a model for studying Down's syndrome.

Down's syndrome sufferers almost always suffer from Alzheimer's as they grow older. Because brain and behavioral studies of Down's syndrome patients reveal conditions identical to those of Alzheimer's patients, researchers believe this mouse may also be a good model for studying Alzheimer's.

Using the rat as animal model, researchers are studying how the disease may affect the brain in the early stages of the disease, before human patients would even be diagnosed. The rat also permits researchers to study how the disease progresses, as well as how safe and effective various drug treatments are at different stages of the disease. Such information can then be used to design safe treatments for Alzheimer's sufferers.

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Parkinson's Disease

Another serious disease of the elderly is Parkinson's disease, a degenerative disorder of the central nervous system. This disease is characterized by increasing loss of muscle control, causing tremors, stiffness, slowness of movements and difficulty in balance. In advanced stages of the disease, sufferers lose the ability to walk, speak or feed themselves, and they eventually die. More than 100,000 Canadians are now suffering from the disease.

Scientists are studying the effectiveness of transplanting embryonic brain tissue (called brain grafts) to both monkeys and rats which have Parkinsonism.  This difficult surgical technique has taken many years to perfect, and has required the use of animal models in its development. Successful surgery permits the brain graft to grow and secrete the chemicals, such as dopamine, which the patient's brain cannot produce on its own. In a 1984 study of Alzheimer's lesions in rats, for example, 73% of the rats who received brain grafts showed better memory skills than they had before the implant of the grafts. Similar improvements have been seen following brain grafting in monkeys with Alzheimer's lesions.

The nematode, an animal which has long been used by developmental and molecular biologists, is also providing important clues to researchers on the mechanisms that cause cell death, information of vital significance to those studying Alzheimer's, Parkinson's and other neurological diseases. Since nerve cell death is the common characteristic of all of these neurological diseases, researchers are using the nematode to learn more about how cells die. Genes that cause nerve cell death in the nematode have been isolated, opening the door to identifying and understanding the biochemical events which underlie the cell deaths. This basic biomedical research on one of the simplest of animals is providing important clues to the mysteries of neurological disease.

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Incidence of Leading Neurological Disorders

It is estimated that more than 5 million Canadians are affected by DISORDERS OF THE BRAIN AND NERVOUS SYSTEM.

• Strokes occur In 1,200 Canadians each day.  Cats are being used to study recovery from strokes.
• Migraine headaches afflict over 24 million Canadians and Americans. Following extensive research and testing with rodents, rabbits and dogs, a new drug is now available to treat migraines.
• Alzheimer's and other dementias affect 1 of every 30 people. More than 200,000 Canadians suffer from Alzheimer's. Primate research has identified one of the important features of Alzheimer's disease:  an abundance of clusters of fibrillary tangles in the brains of patients.
• Epilepsy affects more than 2,500,000 people across North America. Studying seizures in mutant mice, researchers have discovered that petit mal epileptic seizures in these mice are triggered by an over-abundance of GABAb receptors in the brain.
• Parkinson's disease currently affects 100,000 Canadians.  Lobsters are being used to study motor coordination in order to treat diseases like Parkinson's.
• Spinal cord injuries occur in 10,000 Canadians every year: Scientists have stimulated growth of new nerve cells in rats. Injury to the head and/or spinal cord is the leading cause of death and disability in Canada for people under 24 years of age.