Researchers have identified a drug that targets the first step in the toxic chain reaction leading to the death of brain cells, suggesting that treatments could be developed to protect against Alzheimer’s disease, in a similar way to how statins are able to reduce the risk of developing heart disease.
The drug, which is an approved anti-cancer treatment, has been shown to delay the onset of Alzheimer’s disease, both in a test tube and in nematode worms. It has previously been suggested that statin-like drugs – which are safe and can be taken widely by those at risk of developing disease – might be a prospect, but this is the first time that a potential ‘neurostatin’ has been reported.
When the drug was given to nematode worms genetically programmed to develop Alzheimer’s disease, it had no effect once symptoms had already appeared. But when the drug was given to the worms before any symptoms became apparent, no evidence of the condition appeared, raising the possibility that this drug, or other molecules like it, could be used to reduce the risk of developing Alzheimer’s disease. The results are reported in the journal Science Advances.
By analysing the way the drug, called bexarotene, works at the molecular level, the international team of researchers, from the University of Cambridge, Lund University and the University of Groningen, found that it stops the first step in the molecular cascade that leads to the death of brain cells. This step, called primary nucleation, occurs when naturally occurring proteins in the body fold into the wrong shape and stick together with other proteins, eventually forming thin filament-like structures called amyloid fibrils. This process also creates smaller clusters called oligomers, which are highly toxic to nerve cells and are thought to be responsible for brain damage in Alzheimer’s disease.
“The body has a variety of natural defences to protect itself against neurodegeneration, but as we age, these defences become progressively impaired and can get overwhelmed,” said Professor Michele Vendruscolo of Cambridge’s Department of Chemistry, the paper’s senior author. “By understanding how these natural defences work, we might be able to support them by designing drugs that behave in similar ways.”
For the past two decades, researchers have attempted to develop treatments for Alzheimer’s that could stop the aggregation and proliferation of oligomers. However, these attempts have all failed, in part because there was not a precise knowledge of the mechanics of the disease’s development: Vendruscolo and his colleagues have been working to understand exactly that. Using a test developed by study co-author Professor Tuomas Knowles, also from the Department of Chemistry, and by Professor Sara Linse, from Lund University, the researchers were able to determine what happens during each stage of the disease’s development, and also what might happen if one of those stages was somehow switched off.