Errors in DNA may cause dementia, research suggests
Dementia may begin in the womb when mistakes in DNA store up problems for the future, a study by Cambridge University suggests.
Researchers already knew that inherited mutations in some genes make people far more likely to develop neurodegenerative diseases such as Alzheimer’s and Parkinson’s, but the paper claims those same genes can go haywire even when people do not inherit risky variants from parents.
In tissue samples of the brains of 54 people, 40 of whom had varying forms of dementia, scientists discovered that half the subjects had spontaneous flaws in their DNA, which may have contributed to their illness.
The researchers believe the genetic defects occurred before the subjects were born, while they were embryos growing in the womb. And they fear that the same mutations may be carried by a huge proportion of the population, which is why dementia is so prevalent.
“These spelling errors arise in our DNA as cells divide, and could explain why so many people develop diseases such as dementia when the individual has no family history,” said lead author Prof. Patrick Chinnery.
“These mutations likely form when our brain develops before birth — in other words, they are sat there waiting to cause problems when we are older.
“Our discovery may also explain why no two cases of Alzheimer’s or Parkinson’s are the same. Errors in the DNA in different patterns of brain cells may manifest as subtly different symptoms.”
Around 850,000 people suffer from dementia in Britain, which is largely caused when sticky clumps of amyloid plaques form in the brain, preventing neurons from communicating.
Although one in 20 patients who develop neurodegenerative disease have a family history, where genetic variants inherited from their parents raise their risk, the reason why most people get the diseases has remained unknown. Drug trials are already underway for inherited dementia, and the new study suggests that medication which works in those cases may also work for the majority of sufferers.
“The question is: how relevant are these treatments going to be for the ‘common-or-garden’ variety without a family history,” said Chinnery.
“Our data suggests the same genetic mechanisms could be responsible in non-inherited forms of these diseases, so these patients may benefit from the treatments being developed for the rare genetic forms.”
The research was welcomed by charities who said that it could help unravel the role genes play in developing dementia.
Dr. James Pickett, head of research at Alzheimer’s Society, said: “The small errors that can occur as brains develop are often harmless but can sometimes lead to conditions such as cancer or dementia ... it’s interesting to see that many of the mutations in this study were found in the area of the brain that Alzheimer’s starts in.”
The research was published in the journal Nature Communications.