Johns Hopkins Health Alert
The Potential of Repurposed Drugs to Slow Alzheimer’s
Nearly all major pharmaceutical companies in the United States are racing to find a cure for Alzheimer’s disease but since the cause of Alzheimer’s disease is still a mystery, scientists aren’t sure where in the brain to aim treatment. In this health alert, Johns Hopkins discusses the potential of new drugs in development, and drugs that target tau protein tangles and inflammation, instead of amyloid plaques.
Attacking amyloid plaques is an important avenue of Alzheimer’s research, but major questions remain. Autopsy studies have revealed that some people with amyloid plaque buildup do not develop Alzheimer’s disease. And so far studies have not been able to show that reducing plaque in the brain leads to cognitive improvement in patients with Alzheimer’s disease.
Many researchers argue that just because these plaques develop with dementia doesn’t mean they cause Alzheimer’s disease symptoms. It’s possible that amyloid plaques are a reaction to brain damage that has already occurred and are merely indicators of cell death. Another possibility: Plaque may work like scar tissue, protecting (not harming) cells damaged by Alzheimer’s.
Many Alzheimer’s disease researchers are targeting other potential causes, like tau protein tangles and inflammation. They’re also investigating drugs that treat other ailments. One potential dementia therapy in this vein is methylthioninium (Rember), a form of which has been used to treat urinary tract infections (among other things) since the 1930s.
- Methylthioninium may dissolve and prevent tau tangles -- aberrations that accumulate in the brains of Alzheimer’s disease patients as their disease progresses (like amyloid plaques). Tau protein normally helps keep pathways for brain cell nutrients straight, like train tracks. But in people who have Alzheimer’s disease, the protein tangles up, which prevents nutrients from moving through cells.
According to some preliminary findings, a new form of methylthioninium may have stabilized cognitive decline over 50 weeks in 321 patients with mild to moderate disease. No known clinical trials are underway at this time.
- Another repurposed drug is dimebolin (Dimebon), an antihistamine originally marketed in Russia. Researchers hoped it would slow Alzheimer’s disease progression by boosting the energy-producing capacity of brain cells. Patients with Alzheimer’s disease who enrolled in small preliminary trials tolerated the drug well, and cognitive improvements seemed to increase the longer patients stayed on the drug.
Based on this initial Russian work, researchers recruited 598 participants in the U.S., South America, and Europe with mild to moderate Alzheimer’s disease for larger, more definitive Phase III study. After having seen so many “sure hits” come on the scene over the years and then flame out miserably in costly but necessary multi-center Phase III testing, nothing is ever certain except the scientific evidence confirming both the drug’s safety and its ability to truly benefit people with Alzheimer’s disease.
Although many in the Alzheimer’s disease research community held great expectations for Dimebon, all hopes were recently crushed when two late-stage trial results revealed that when compared to placebo Dimebon had no effect whatsoever in treating the cognitive deficits or behavioral problems triggered by Alzheimer’s disease.
- Finally, some observational studies have found an association between taking the cholesterol drugs called statins and a reduced risk of developing Alzheimer’s disease. One possible explanation is that lowering cholesterol levels improves blood vessel function in the brain. But several randomized, placebo-controlled clinical trials have found that statins offer no benefit for people who already have Alzheimer’s disease. And the latest clinical trials suggest that these drugs may not protect against the development of Alzheimer’s either.
Posted in Memory on March 8, 2010
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
Notify Me
Would you like us to inform you when we post new Memory Health Alerts?
Comments
Health Alerts registered users may post comments and share experiences here at their own discretion. We regret that questions on individual health concerns to the Johns Hopkins editors cannot be answered in this space.
The views expressed here do not constitute medical advice, and do not represent the position of Johns Hopkins Medicine or Remedy Health Media, LLC, which has no responsibility for any comments posted on this site.
Post a Comment
Already a subscriber?
Login
New to Johns Hopkins Health Alerts?
