Alzheimer's disease: what we know now.

Advances in Alzheimer's-disease-related knowledge are a regular staple of today's news. A brief updating from the Alzheimer's Association

Long-term care facilities are witnessing continuing growth in the number of residents with Alzheimer's disease and, with the aging of baby boomers, facilities can expect this trend to accelerate. In fact, unless a cure or prevention is found, the number of Americans with Alzheimer's disease will more than triple, from 4 million to 14 million, by the middle of the next century. With this sort of prospect in view, it's important that long-term care professionals keep informed about the latest in Alzheimer's research.

More has been learned about Alzheimer's disease in the past few years than in all of the last century. Progress has been made in gaining a deeper understanding of the disease process, diagnosis, possible causes and potential treatments to help those who suffer, as well as prevention. The following briefly summarizes the current state of knowledge.

Pathology

The pathology of Alzheimer's disease has been under great scrutiny since the beginning of the century, when Alois Alzheimer reported the first case of the disease. For decades now, scientists have known about two lesions that are characteristic of Alzheimer's disease - amyloid plaques and neurofibrillary tangles - that are found in the brains of all affected individuals.

In the last year, several key studies have improved our understanding of these lesions and the protein deposits within them. More recently, a third lesion called an AMY plaque was detected and also may prove to be characteristic of Alzheimer's disease, leading researchers down a previously unexplored path of study.

Genetics

To date, mutations in three genes have been linked to early-onset Alzheimer's (which occurs before age 65): PS2, PS1 and APP, located on chromosomes 1, 14 and 21, respectively. In 1993, a fourth gene, APOE-e4 on chromosome 19, was declared a susceptibility or risk gene for late-onset Alzheimer's disease (occurring in individuals age 65 and over). Recent studies might have found two more potential susceptibility genes for late-onset Alzheimer's, but these require further investigation. Advanced study of the genetics of this disease has led researchers to believe other genes, or possibly environmental factors, may be involved.

Diagnosis

Although the exact causes of Alzheimer's are not yet known, new diagnostic tools and criteria make it possible to obtain a diagnosis of probable Alzheimer's with an accuracy of 85 to 90%. Scientists are continuously researching new, more effective diagnostic tests in an effort to make it easier to diagnose Alzheimer's disease in the early stages. Being able to recognize symptoms early and obtain an accurate diagnosis gives affected individuals a greater chance of benefiting from existing treatments and preparing for the future.

Treatment

A decade ago, very few compounds were being developed specifically for Alzheimer's disease. Today, dozens of compounds are being studied in the search for medications to improve cognitive and behavioral symptoms and potentially slow progression of the disease.

Several experimental drugs have begun to show promise in enhancing nerve cell communication, regulating defective cell processes, protecting nerve cells from damage brought on by Alzheimer's and repairing damaged nerve cells in the brain. Within the last five years, two drugs, tacrine and donepezil, have been approved by the Food and Drug Administration (FDA) for the treatment of Alzheimer's disease. Several others are expected to be approved by the FDA within the next couple of years.

Recently, researchers have studied several other proposed drug therapies for Alzheimer's disease. Their use is still experimental, although many physicians have recommended and administered them to their patients. Nevertheless, further research is needed in order to determine the exact benefits and risks of the following drugs when prescribed to patients with Alzheimer's disease:

* Antioxidants, such as Vitamin E or selegiline, which is commonly used for treatment of Parkinson's disease, may help reduce oxidative damage to nerve cells. In a two-year study, researchers found that high dosages of vitamin E (2,000 IUs) helped middle-stage Alzheimer's patients longer maintain their ability to perform daily activities, such as bathing, dressing, etc. The patients did not show significant improvement, but their deterioration was slowed.

* Nonsteroidal anti-inflammatory drugs (NSAIDs) may aid in preventing or delaying the onset of Alzheimer's by protecting nerve cells in the brain from inflammation that may contribute to nerve cell damage. Population studies have shown that individuals who have taken NSAIDs, such as ibuprofen, for pain relief in the past may be at lower risk for developing Alzheimer's disease in the future.

* Estrogen may counteract the damage inflicted by Alzheimer's by performing several positive functions: increasing the amount of acetylcholine in the brain, enhancing the brain's antioxidant properties and increasing nerve cell growth. In some studies, estrogen has been shown to improve cognition in those with Alzheimer's, and may have a protective effect in asymptomatic individuals. Definitive studies are under way.

* Ginkgo biloba may have a slightly positive effect on individuals with Alzheimer's disease. A recent preliminary study produced very modest results in individuals treated with ginkgo biloba. Study participants experienced a slowing in loss of ability to perform activities of daily living and in disruptive social behavior, although no measurable difference was noted in subjects' overall impairment.

In general, while today's treatments provide only symptomatic relief, the next generation of treatments may delay onset or slow progression by protecting nerve cells for a longer period of time.

Caregiving

Increasingly, social and behavioral scientists are turning their attention to discovering the most effective methods of providing dementia-capable care, and family care research is becoming more rigorous and focused.

Building on existing research into caregiving, the Alzheimer's Association has developed training opportunities for care professionals, including nurses and activity directors. The Association has also developed a unique document called Key Elements of Dementia Care, which defines, describes and illustrates dementia-capable care throughout the range of residential care settings.

For more information on Alzheimer's disease, the latest in research and providing dementia-capable care, contact the Alzheimer's Association at [phone].

Daniela Sikanovski is a research information specialist for the Alzheimer's Association, based in Chicago, IL. She also is the editor of Research & Practice, the association's quarterly newsletter on Alzheimer's disease for healthcare professionals.