University of Virginia Health System

Eating Fish May Reduce Alzheimer's Disease Risk

Dietary Questionnaire Points To Findings

< July 23, 2003 >A new study reported in The Archives of Neurology shows eating foods that contain n-3 fatty acids and weekly consumption of fish may reduce the risk of developing Alzheimer's disease later in life.

N-3 fatty acids are found in foods including fish, nuts, and oil-based salad dressings.

Alzheimer's disease is a progressive, neurodegenerative disease characterized by memory loss, decline in language abilities, impaired visuospatial skills, poor judgment, and indifferent attitude, according to the National Institute of Neurological Disorders and Stroke (NINDS) of the National Institutes of Health (NIH).

Alzheimer's disease usually begins after age 65. However, the onset of the disease may occur as early as age 40, appearing first as memory decline and, over several years, causing a deterioration in cognition, personality, and ability to function.

Confusion and restlessness may also occur, NINDS  states. The early symptoms of Alzheimer's disease, which include forgetfulness and loss of concentration, can be missed easily because they resemble natural signs of aging.

Similar symptoms can also result from fatigue, grief, depression, illness, vision or hearing loss, the use of alcohol or certain medications, or simply the burden of too many details to remember at once, according to NINDS.

Fish, Nuts, and Oil-Based Dressings Help

Experts say because brain cell membranes contain n-3 polyunsaturated fatty acids, studies have been done in the lab to look at the relationship between these fatty acids and Alzheimer's disease in animals. The earlier studies show that lab animals fed diets enriched with n-3 polyunsaturated fatty acids have better nerve function and enhanced learning and memory.

Now, a new study conducted by Dr. Martha Clare Morris of Rush-Presbyterian St. Luke's Medical Center in Chicago, and her colleagues, looks at whether the consumption of fish and n-3 fatty acids is associated with reduced risk of Alzheimer's disease in humans.

The researchers studied 815 residents of a Chicago community who were aged 65 to 94 years old who did not have Alzheimer's disease at the beginning of the study and who completed a dietary questionnaire an average of 2.3 years before they were evaluated for the disease. The study was conducted between 1993 and 2000.

The researchers found that a total of 131 participants developed Alzheimer's disease over an average followup of 3.9 years. Participants who ate fish once per week or more had a 60 percent lower risk of Alzheimer's disease compared with those who rarely or never ate fish.

The overall consumption of n-3 polyunsaturated fatty acids was associated with a reduced risk. The researchers also found that the associations remained unchanged when they adjusted for consumption of other dietary fats and vitamin E consumption.

"A large number of animal studies have demonstrated that dietary n-3 fatty acids increased learning acquisition and memory performance, and two epidemiologic studies found decreased risk of Alzheimer disease with increased fish consumption," write the authors in The Archives of Neurology.

"These studies, together with our finding that consumption of fish and n-3 fatty acids was associated with reduced risk of Alzheimer disease, provide a strong basis for further study through epidemiologic investigations and clinical trials.

"Our findings suggest that consumption of fish (at least weekly), oil-based salad dressings and nuts may reduce the risk of Alzheimer disease," the researchers conclude.

Well-Balanced Eating Plan Suggested

In an accompanying editorial in The Archives of Neurology, Dr. Robert P. Friedland of Case Western Reserve University School of Medicine in Cleveland says, "The causal web for AD [Alzheimer's] is remarkably complex, as cardiovascular disease, stroke, hypertension, and diabetes are all risk factors for the disease.

"Consequently, dietary and other hazards enhancing the presence of these conditions increase the probability of getting AD [Alzheimer's disease] as well, " Dr. Friedland says.

"Fish is a good source of high-quality protein, as well as PUFAs [polyunsaturated fatty acids], and is low in saturated fats," Dr. Friedland says.

"However, the beneficial effects of PUFAs from fish may be counterbalanced by toxins. Fish may contain dangerous levels of polychlorinated biphenyls and mercury from coal-fired power plants (especially methylmercury)," cautions Dr. Friedland.

"Dietary intake is best considered from the point of view of diet patterns, rather than individual foods," Dr. Friedland says. "A high antioxidant/low saturated fat diet pattern with a greater amount of fish, chicken, fruits, and vegetables, and less red meat and dairy products, is likely to lower the risk of AD [Alzheimer's disease], as well as that for heart disease and stroke."

Always consult your physician for more information.

Online Resources

(Our Organization is not responsible for the content of Internet sites.)

Alzheimer's Association

Centers for Disease Control and Prevention (CDC)

National Institutes of Health (NIH)

National Institute of Neurological Disorders and Stroke (NINDS)

National Institute on Aging (NIA) Alzheimer's Disease Education and Referral Center

The Archives of Neurology

US Department of Health and Human Services (HHS)

For more information on health and wellness, please visit health information modules on this Web site.

How Is Alzheimer's Disease Diagnosed?

There is not a single, comprehensive test for diagnosing Alzheimer's disease. By ruling out other conditions through a process of elimination, physicians, or other specialists, can obtain a diagnosis of probable Alzheimer's disease with approximately 90 percent accuracy.

Examination and evaluation are essential in determining whether the dementia is the result of a treatable illness.

In addition to a complete medical history and physical examination, diagnostic procedures for Alzheimer's disease may include the following:

• mental status test

• blood work
  

• chest x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
  

• computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
  

Treatment for Alzheimer's Disease

Specific treatment for Alzheimer's disease will be determined by your physician based on:

• your age, overall health, and medical history
  

• your tolerance for specific medications, procedures, or therapies
  

• your opinion or preference
  

At this time, there is no cure for Alzheimer's, no way of slowing down the progression of this disease, and no treatment available to reverse the deterioration of Alzheimer's disease.

New research findings give reason for hope, and several drugs are being studied in clinical trials to determine if they can slow the progress of the disease or improve memory for a period of time.

There are some medications available to assist in managing some of the most troubling symptoms of Alzheimer's disease, including the following:

• depression
  
  
• behavioral disturbance
  
  
• sleeplessness

In managing the disease, physical exercise and social activity are important, as are proper nutrition, health maintenance, and a calm and well-structured environment.

Always consult your physician for more information.