Despite many promising leads, new treatments for Alzheimer's are slow to emerge.By Mayo Clinic Staff
Current Alzheimer's treatments temporarily improve symptoms of memory loss and problems with thinking and reasoning.
These Alzheimer's treatments boost performance of chemicals in the brain that carry information from one brain cell to another. However, these treatments don't stop the underlying decline and death of brain cells. As more cells die, Alzheimer's disease continues to progress.
Experts are cautiously hopeful about developing Alzheimer's treatments that can stop or significantly delay the progression of Alzheimer's. A growing understanding of how the disease disrupts the brain has led to potential Alzheimer's treatments that short-circuit basic disease processes.
Future Alzheimer's treatments may include a combination of medications, similar to how treatments for many cancers or HIV/AIDS include more than a single compound.
The following treatment options are among the strategies currently being studied.
Some of the new Alzheimer's treatments in development target microscopic clumps of the protein beta-amyloid (plaques). Plaques are a characteristic sign of Alzheimer's disease.
Strategies aimed at beta-amyloid include:
Recruiting the immune system. Several drugs — known as monoclonal antibodies — may prevent beta-amyloid from clumping into plaques and help the body clear the beta-amyloid from the brain. Monoclonal antibodies mimic the antibodies your body naturally produces as part of your immune system's response to foreign invaders or vaccines.
Recent research on the monoclonal antibody solanezumab found a possible benefit for people with mild Alzheimer's disease. The drug appeared to be more effective when it was given earlier in the course of the disease. The drug seemed safe in the most recent research. Further studies are in the works.
Aducanumab is another drug that has shown promise in preliminary studies. More studies are underway for this treatment.
Preventing destruction. Several years ago, researchers learned that beta-amyloid interacts with another protein called Fyn. When combined with beta-amyloid, Fyn is over-activated, which triggers a destruction of connections between nerve cells (synapses) in the brain.
A drug initially developed as a possible cancer treatment — saracatinib — is now being tested in Alzheimer's disease.
In mice, the drug turned off Fyn, which allowed synapses to start working again and the animals experienced a reversal of some memory loss. A human trial is now underway.
Production blockers. These therapies may reduce the amount of beta-amyloid formed in the brain. Research has shown that beta-amyloid is produced from a "parent protein" in two steps performed by different enzymes.
Several experimental drugs aim to block the activity of these enzymes. They're known as beta- and gamma-secretase inhibitors.
A vital brain cell transport system collapses when a protein called tau twists into microscopic fibers called tangles, which are another common brain abnormality of Alzheimer's. Researchers are looking at a way to prevent tau from forming tangles.
Tau aggregation inhibitors and tau vaccines are currently being studied in clinical trials.
Alzheimer's causes chronic, low-level brain cell inflammation. Researchers are studying ways to treat inflammatory processes at work in Alzheimer's disease.
Researchers are also studying the diabetes drug pioglitazone (Actos) because it may lessen beta-amyloid and inflammation in the brain.
Researchers are studying the effects of insulin on the brain and brain cell function, and insulin changes in the brain that may be related to Alzheimer's. A trial is testing an insulin nasal spray to determine if it slows the progression of Alzheimer's.
Growing evidence suggests that brain health is closely linked to heart and blood vessel health. The risk of developing Alzheimer's appears to increase as a result of many conditions that damage the heart or arteries. These include high blood pressure, heart disease, stroke, diabetes and high cholesterol.
A number of studies are exploring how best to build on this connection. Strategies under investigation include:
- Current drugs for heart disease risk factors. Researchers are investigating whether drugs now used to treat vascular disease such as blood pressure medications may also help people with Alzheimer's or reduce the risk of developing the disease.
- Drugs aimed at new targets. Additional projects are looking more closely at how the connection between heart disease and Alzheimer's works at the molecular level to find new drug targets.
- Lifestyle choices. Researchers have explored whether lifestyle choices with known heart benefits, such as exercising on most days and eating a heart-healthy diet, may help prevent Alzheimer's disease or delay its onset.
In one study, taking estrogen-based hormone therapy for at least a year during peri-menopause or early menopause appeared to protect thinking and memory in women with a higher risk of Alzheimer's disease.
This finding highlights the importance of timing — certain interventions may only be helpful at specific times. The overall findings on hormone therapy, however, are mixed and further research is needed before any recommendations can be made.
Developing new medications is a slow and painstaking process. The pace can be especially frustrating for people with Alzheimer's and their families who are waiting for new treatment options.
To help accelerate discovery, the Coalition Against Major Diseases (CAMD), an alliance of pharmaceutical companies, nonprofit foundations and government advisers, have forged a first-of-its-kind partnership to share data from Alzheimer's clinical trials.
Researchers anticipate that sharing these data from more than 4,000 study participants will speed development of more-effective therapies.
Feb. 26, 2016