Latent viruses hiding in the brain could be activated by a head injury and trigger Alzheimer’s, research suggests.
Studies have long warned that concussions and blows to the head can increase the risk of neurodegenerative diseases.
But now, scientists believe these types of injuries could “awaken” dormant viruses in the brain, causing inflammation and long-term damage that leads to dementia.
The main concern revolves around herpes viruses, including herpes simplex virus (HSV-1), which causes cold sores and is carried by four in five adults.
It is also estimated that up to 95 percent carry the varicella-zoster virus, another type of herpes virus that causes chickenpox and shingles.
The scientists, from the United Kingdom and the United States, hope that these promising findings, made in laboratories and not in humans, can help accelerate research into antiviral drugs for herpes that can slow the onset of degenerative diseases.
Professor Ruth Itzhaki, Visiting Fellow at the Institute of Population Aging at the University of Oxford, said: “What we have discovered is that in the brain model these lesions can reactivate a latent virus, HSV-1.
“This triggers inflammation that, in the brain, would cause the same changes that we see in Alzheimer’s patients.”
Scientists believe that head injuries could “awaken” dormant herpes viruses in the brain, causing inflammation and long-term damage.
Studies have long warned that concussions and blows to the head can increase the risk of neurodegenerative diseases. Former rugby player Steve Thompson was diagnosed with early-onset dementia at the age of 43.
Dr. Dana Cairns, a research associate in biomedical engineering at Tufts University in Boston, added: “This raises the question of whether antiviral drugs or anti-inflammatory agents could be useful as early preventative treatments after head trauma to stop the activation of HSV-1 in its tracks and reduce the risk of Alzheimer’s disease.’
In the study, researchers recreated a brain model in the lab, placing it in a cylinder to mimic the skull.
Some of the brain cells had been infected with the latent herpes simplex virus (HSV-1), which causes cold sores.
They then gave the mini-brains a single sharp blow with a piston to mimic a traumatic head injury or a series of smaller jolts to mimic the effects of a milder periodic concussion.
When brain tissues were exposed to repeated “soft hits,” the previously dormant HSV-1 virus was activated.
This reactivation triggered inflammation, accumulation of beta-amyloid plaque, and the formation of harmful tau proteins, characteristic markers of Alzheimer’s disease.
There was also evidence of decreased brain cell function.
Other blows to brain tissue, which mimicked repetitive head injuries, caused more severe damage, but brain cells without herpes infection did not have the same problems from the blows.
Alzheimer’s disease is the most common cause of dementia. The disease can cause anxiety, confusion and short-term memory loss.
writing in the diary Scientific advancesThe scientists said: “We suggest that after brain injury from repeated mechanical shocks in life, the resulting reactivation of HSV-1 in the brain leads to the development of Alzheimer’s disease/dementia.”
“(This suggests) that HSV-1 is one of the main causes of Alzheimer’s.”
However, other scientists who were not involved in the study have urged caution with the findings.
Professor Robert Howard, Professor of Old Age Psychiatry at University College London, said: “The study is interesting and raises a potential mechanism for the observed association between cold sore virus infection, brain lesions and the disease. of Alzheimer’s.
«However, as is often the case in science, it is very important to keep in mind that association does not mean causation.
“Much more research will be needed before this can be seriously considered as a plausible mechanism for the development of dementia.
“It is already known that avoiding brain injuries, such as those that occur in some contact sports, is an important way to prevent dementia and I am not convinced that this reflects anything more complicated than mechanical damage that causes cell death. “brains”.
Research has suggested that multiple blows to the head can more than double your chances of suffering from a neurodegenerative disease months or years later.
Sir Bobby Charlton (pictured holding a ball with United written on it during an interview with local press in a Hong Kong hotel in 2005) died, aged 86, with dementia in 2023.
Former England and West Bromwich Albion striker Jeff Astle has died aged 59 from an early-onset illness, reportedly due to repeated head trauma.
Contact sports have been marred by controversy due to their links to dementia and other brain diseases in players, which are believed to result from frequent head impacts.
Most famously, former English soccer player Sir Bobby Charlton died at age 86 in 2023, years after being diagnosed with dementia.
Former England and West Bromwich Albion striker Jeff Astle has died aged 59 from an early-onset illness, reportedly due to repeated head trauma.
Former rugby player Steve Thompson was also diagnosed with early-onset dementia at the age of 43.
A 2023 study commissioned by the Football Association and the Professional Footballers’ Association found that professional footballers are three times more likely to be diagnosed with dementia than the general population.
But research published last year by scientists at the University of New South Wales in Australia found that those who experienced a concussion while playing sports during their lifetime had marginally better cognitive performance than those who reported no concussions.
A recent analysis by the Alzheimer’s Society estimates that the total annual cost of dementia in the UK is £42 billion a year, with families hardest hit.
An aging population means these costs – which include lost income from unpaid carers – will soar to £90 billion over the next 15 years.
It is currently believed that around 900,000 Britons suffer from this memory-robbing disorder. But scientists at University College London estimate this figure will rise to 1.7 million within two decades as people live longer. It marks a 40 percent increase from the previous forecast in 2017.
Around 944,000 people in the UK are thought to be living with dementia, while in the US the figure is around 7 million.
Alzheimer’s affects approximately six in 10 people with dementia.
Memory problems, thinking and reasoning difficulties, and language problems are common early symptoms of the condition, which then worsen over time.
Dementia is expected to skyrocket in the coming years, so a cheap screening tool is vital to meeting the challenge.
Analysis by Alzheimer’s Research UK found that 74,261 people died from dementia in 2022, compared to 69,178 the previous year, making it the leading cause of death in the country.