Alzheimer's Disease and CAM: What the Science Says

(Extraído de nccam.nih.gov)

According to the National Institute on Aging, Alzheimer's disease affects nearly 4.5 million Americans and is the most common form of dementia in the elderly. Alzheimer's disease is an incurable disease with a slow progression beginning with mild memory loss and ending with severe brain damage and death.

While no treatment is proven to stop Alzheimer's disease, some conventional drugs may limit symptoms for a short period of time in the early stages of the disease. Research on several dietary supplements is ongoing to determine whether they are effective in preventing or slowing the progression of Alzheimer's disease. This issue provides information on "what the science says" about the effectiveness of antioxidants, Asian ginseng, cat's claw, ginkgo, and grape seed extract for Alzheimer's disease.

Antioxidants

Scientific Evidence

• Because antioxidants are widely used, and because there is laboratory and observational evidence of potential health benefits, antioxidants are the subject of extensive research across NIH, including recent NCCAM-sponsored studies that have been investigating alpha-lipoic acid and fish oil to slow the progression of Alzheimer's disease.
• Currently, there is not enough scientific evidence to determine whether antioxidants such as alpha-lipoic acid and fish oil are effective for the treatment of Alzheimer's disease.

Side Effects and Cautions

• Omega-3s appear to be safe for most adults at low-to-moderate doses. The FDA has concluded that omega-3 dietary supplements from fish are "generally recognized as safe."
• Some have questioned the safety of fish oil supplements because some species of fish can contain high levels of mercury, pesticides, or polychlorinated biphenyls (PCBs). However, fish oil supplements do not appear to contain these substances.
• Fish oil supplements may cause minor gastrointestinal upsets, including diarrhea, heartburn, indigestion, and abdominal bloating.
• In high doses, fish oil can interact with certain medications, including blood thinners and drugs used for high blood pressure.

Asian Ginseng

Scientific Evidence

• NCCAM supports studies to better understand the use of Asian ginseng. Areas of recent NCCAM-funded research include the herb's potential effects on insulin resistance, cancer, and Alzheimer's disease.
• Although Asian ginseng has been widely studied for a variety of uses, research results to date do not conclusively support health claims associated with the herb. Only a few large, high-quality clinical trials have been conducted. Most evidence is preliminary—i.e., based on laboratory research or small clinical trials.

Side Effects and Cautions

• Short-term use of ginseng at recommended doses appears to be safe for most people. Some sources suggest that prolonged use might cause side effects.
• The most common side effects are headaches and sleep and gastrointestinal problems.
• Asian ginseng can cause allergic reactions.
• There have been reports of breast tenderness, menstrual irregularities, and high blood pressure associated with Asian ginseng products, but these products' components were not analyzed, so effects may have been due to another herb or drug in the product.
• Asian ginseng may lower levels of blood sugar; this effect may be seen more in people with diabetes. Therefore, people with diabetes should use extra caution with Asian ginseng, especially if they are using medicines to lower blood sugar or taking other herbs, such as bitter melon and fenugreek, that are also thought to lower blood sugar.

Cat's Claw

Scientific Evidence

• The National Institute on Aging funded a study that looked at how cat's claw may affect the brain. Findings may point to new avenues for research in Alzheimer's disease treatment. However, there is not enough scientific evidence to determine whether cat's claw works for Alzheimer's disease or any other health condition.

Side Effects and Cautions

• Few side effects have been reported for cat's claw when it is taken at recommended dosages. Though rare, side effects may include headaches, dizziness, and vomiting.
• Women who are pregnant or trying to become pregnant should avoid using cat's claw because of its past use for preventing and aborting pregnancy.
• Because cat's claw may stimulate the immune system, it is unclear whether the herb is safe for people with conditions affecting the immune system.
• Cat's claw may interfere with controlling blood pressure during or after surgery.

Ginkgo

Scientific Evidence

• Numerous studies of ginkgo have been done for a variety of conditions, including Alzheimer's disease and dementia.
• An NCCAM-funded study of the well-characterized ginkgo product EGb-761 found it ineffective in lowering the overall incidence of dementia and Alzheimer's disease in the elderly. Further analysis of the same data also found ginkgo to be ineffective in slowing cognitive decline, lowering blood pressure, or reducing the incidence of hypertension. In this clinical trial, known as the Ginkgo Evaluation of Memory study, researchers recruited more than 3,000 volunteers age 75 and over who took 240 mg of ginkgo daily. Participants were followed for an average of approximately 6 years.
• Some smaller studies of ginkgo for memory enhancement have had promising results, but a trial sponsored by the National Institute on Aging of more than 200 healthy adults over age 60 found that ginkgo taken for 6 weeks did not improve memory.

Side Effects and Cautions

• Side effects of ginkgo may include headache, nausea, gastrointestinal upset, diarrhea, dizziness, or allergic skin reactions. More severe allergic reactions have occasionally been reported.
• There are some data to suggest that ginkgo can increase bleeding risk, so people who take anticoagulant drugs, have bleeding disorders, or have scheduled surgery or dental procedures should use caution and talk to a health care provider if using ginkgo.
• Fresh (raw) ginkgo seeds contain large amounts of a chemical called ginkgotoxin, which can cause serious adverse reactions—even seizures and death. Roasted seeds can also be dangerous. Products made from standardized ginkgo leaf extracts contain little ginkgotoxin and appear to be safe when used orally and appropriately.

Grape Seed Extract

Scientific Evidence

• NCCAM is studying whether the action of grape seed extract and its components may benefit the heart or help prevent cognitive decline, Alzheimer's disease, and other brain disorders. More research is needed to determine if grape seed extract is effective for the prevention of Alzheimer's disease.

Side Effects and Cautions

• Grape seed extract is generally well tolerated when taken by mouth. It has been used safely for up to 8 weeks in clinical trials.
• Side effects that have been reported include a dry, itchy scalp; dizziness; headache; high blood pressure; hives; indigestion; and nausea.
• Interactions between grape seed extract and medicines or other supplements have not been carefully studied.