A compound that interferes with the progress of Huntington's disease has been discovered by US researchers.
Huntington's is linked to protein clumps in brain cells
Clumping of proteins is thought to cause the disease, but a compound called B2 was found to promote large clumps which could be protective.
The find could lead to a new treatment for the neurodegenerative condition.
Massachusetts Institute of Technology and Harvard Medical School collaborated on the Proceedings of the National Academy of Sciences study.
Huntington's usually strikes in midlife and causes uncontrolled movements, loss of cognitive function and emotional disturbance.
There are drugs that can help with the symptoms - but none that can stop the onset or the course of the disease.
The researchers hope their new compound might lead to a drug that can stop the deadly sequence of cellular events that Huntington's unleashes.
The condition is caused by misfolded proteins - called huntingtin proteins - that clump together.
It is thought the proteins disrupt the function of structures known as proteasomes, which act to keep cells clean and free of potentially damaging debris.
With the proteasomes neutralised the proteins accumulate in ever larger number until they poison the cell.
This leads to tissue loss in two key areas of the brain, the striatum, which plays a role in motor and learning functions, and the cortex, responsible for thought.
Until now, most researchers looking for Huntington's treatments have focused on compounds that prevent or reverse the clumping of huntingtin proteins.
However, recent evidence suggests that the largest clumps may not necessarily be harmful and could in fact be protective.
With this in mind, the MIT and Harvard scientists looked for compounds that actually promoted the formation of large clumps.
The highest concentration of protein clumps was found when the researchers applied a compound they called B2 to cells cultivated in the laboratory.
The compound also blocked proteasome disruption - thus blocking one of the toxic effects of the huntingtin protein.
The B2 compound has also shown promise as a way to combat Parkinson's disease.
The researchers are now working on finding a more potent version of the compound that could be tested in mice.
Professor Anne Rosser, professor of clinical neurology at Cardiff University, said there had been much debate about whether the protein clumps seen in Huntington's were harmful or helpful.
"These findings are interesting as they support the latter. This would be quite a new approach to treatment and has implications for the methods used to screen drugs for Huntington's disease."
However, Professor Rosser stressed the work was still at a very early stage.
"It can be a very long road from an interesting laboratory finding to a substance that is ready to test in clinical trials.
"It is also important to emphasise that many compounds that look interesting in laboratory tests prove to be ineffective in humans for a variety of reasons."
Professor John Mayer, of the University of Nottingham, said other work had focused on stimulating brain cells to clean themselves - the autophagic process.
"A cocktail of inhibitors is probably the way forward in Huntington's disease and the other chronic neurodegenerative diseases."