A widely-used drug might help treat children with a condition that ages them up to eight times too quickly, Durham University researchers believe.
People with progeria also suffer heart problems, lack of growth and loss of body fat and hair.
Writing in Human Molecular Genetics, scientists said the condition was partly down to DNA damage caused by highly reactive oxygen chemicals.
They said the drug, n-acetylcysteine, could control the damage.
The average life expectancy for someone with the condition is about 13 years.
Their cells show significant defects, which researchers put into two categories: damage to the DNA and physical disruption of the cell's shape.
Prof Christopher Hutchinson, who led the study, said trials for drugs to correct the shape problems were showing some success.
He has been investigating the cause of, and simple solutions to, the damage to the genetic code.
The team at Durham University found that levels of damaging "reactive oxygen species" were five to 10 times higher in cells of patients with accelerated ageing.
They used n-acetylcysteine, which is already used to prevent liver damage in patients who have overdosed on paracetamol, on cells in the laboratory.
The drug soaked up the reactive oxygen. DNA damage in the cells then returned to "approximately normal levels".
Prof Hutchinson said: "For us it is very exciting."
However, it is unknown what the effect would be if the drug was given to children with the illness or how it would work with other drugs.
Prof Hutchinson told the BBC: "I have to say this is one more piece in the jigsaw which will eventually allow us generate treatments, but it is one more piece."
A full randomised clinical trial of the drug is not possible as the condition is so rare. The Progeria Research Foundation says there are just 78 children known to have the condition.
Its medical director Dr Leslie Gordon said: "[Prof] Hutchison's study has not only confirmed basic cellular defects in progeria, but has also identified potential ways to improve those defects.
"This type of biological science is how progress towards treatments and a cure for children with progeria will advance."
The findings might also one day have benefits for ageing in the wider populations.
Prof Hutchinson said: "If you give a child a drug which extends lifespan without adverse affects then you would expect these to be useful in an older population."