Getting shingles can increase the risk of Alzheimer’s disease, scientists have warned.
A study conducted by the University of Oxford found that the infection can trigger a chain reaction in the brain linked to dementia.
It does this by waking up a different, normally harmless herpes virus that has lain dormant in our bodies since childhood.
This leads to a “dramatic” buildup of plaque and inflammation in the brain – two hallmarks of Alzheimer’s disease.
Chickenpox occurs when the body is first exposed to varicella zoster virus (VZV), usually during childhood. Shingles is the result of subsequent infections.
The researchers used lab-grown brain cells to create a three-dimensional brain to see the impact of VZV on the brain.
They found that it did not directly trigger the signature changes associated with Alzheimer’s disease.
But it reactivated the simplex virus (HSV-1), best known for causing cold sores, triggering a rapid buildup of harmful proteins.
Study author Dana Cairns, from Tufts University in Massachusetts, said: ‘It’s a double punch of two viruses that are very common and generally harmless.
Getting shingles may increase the risk of Alzheimer’s disease by setting off a chain reaction in the brain, scientists have warned (file image)
“But lab studies suggest that if further exposure to VZV awakens dormant HSV-1, it could cause problems.”
HSV-1 normally lies dormant in the body and there is strong evidence that it could be linked to dementia.
Air pollution causes dementia, UK government admits for the first time
Air pollution is fueling a rise in dementia, the UK government has acknowledged for the first time.
Toxic airborne particles from cars and fossil fuels have long been linked to rapidly rising rates of the disease in the UK and the developed world.
Now, a major independent review has confirmed the link after analyzing dozens of human studies.
The researchers concluded that it was “likely that air pollution may contribute to a decline in mental abilities and dementia in older people”.
They believe this occurs primarily through tiny toxic particles that seep into the bloodstream after being breathed into the lungs.
The pollutants then irritate the blood vessels and disrupt circulation to the brain. Over time, this can lead to vascular dementia.
It is also likely that in rare cases, very small particles of air pollution can cross the blood-brain barrier and directly damage neurons.
But this does not appear to be a significant mechanism for the level of air pollution currently in the UK, according to the report.
Previous research has indicated that older people with high levels of the virus in their brains are at a much higher risk of developing Alzheimer’s disease.
Professor Ruth Itzhaki, from the University of Manchester, worked with researchers from the Oxford Institute for Population Aging and Tufts University on the latest study.
The researchers recreated brain-like environments in 6-millimeter-wide doughnut-shaped sponges made of silk proteins and collagen.
They populated the sponges with stem cells that grew into neurons and were able to transmit signals to each other, just as they do in the brain.
The results showed that brain neurons can be infected with VZV, but this alone does not lead to plaque formation and cell death.
Neurons infected with the virus were still able to function normally.
However, if the cells also harbored HSV-1, there was a dramatic increase in tau and beta-amyloid proteins, which are strongly linked to dementia.
Neural signals also began to slow down.
Professor Itzhaki said: ‘This striking result appears to confirm that, in humans, infections such as VZV can cause increased inflammation in the brain, which can reactivate dormant HSV-1.
“Damage to the brain from repeated infections throughout life would eventually lead to the development of Alzheimer’s disease and dementia.
“This would mean that vaccines could play a bigger role than just protecting against a single disease, because they could also indirectly, by reducing infections, provide some protection against Alzheimer’s disease.”
The study was published in the Journal of Alzheimer’s Disease.
Shingles can be very painful and tends to affect people more frequently as they get older.
About one in five people who have had chickenpox develop shingles, and most are in their 60s.
Researchers also warn that obesity, smoking, alcohol and head trauma could also increase the risk of Alzheimer’s disease by weakening the immune system and activating dormant HSV1 in the brain.
Over 900,000 people are now living with dementia in the UK, which is expected to rise to 1.6 million by 2040
Alzheimer’s disease is the most common type of dementia.
Current estimates indicate that approximately 5.8 million people in the United States suffer from the disease, most of whom are over the age of 65.
WHAT IS DEMENTIA? THE BLURRED DISEASE THAT STEALS PEOPLE SUFFERING FROM THEIR MEMORIES
A GLOBAL CHALLENGE
Dementia is an umbrella term used to describe a range of progressive neurological disorders (those that affect the brain) that impact memory, thinking and behavior.
There are many types of dementia, of which Alzheimer’s disease is the most common.
Some people may have a combination of dementia types.
Regardless of the type diagnosed, each person will experience dementia in their own way.
Dementia is a global concern, but is most commonly seen in wealthier countries, where people are likely to live to very old ages.
HOW MANY PEOPLE ARE AFFECTED?
The Alzheimer’s Society reports that there are over 900,000 people with dementia in the UK today. This figure is expected to reach 1.6 million by 2040.
Alzheimer’s disease is the most common type of dementia, affecting between 50 and 75% of those diagnosed.
In the United States, it is estimated that there are 6 million people with Alzheimer’s disease. A similar percentage increase is expected in the coming years.
As a person’s age increases, the risk of developing dementia also increases.
Diagnosis rates are improving, but it is believed that many people with dementia remain undiagnosed.
IS THERE A CURE?
Currently, there is no cure for dementia.
But new drugs can slow its progression and the earlier it is spotted, the more effective the treatments.
Source: Alzheimer Society