Catching shingles may increase Alzheimer’s risk, scientists warn.
A study led 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 another normally harmless herpes virus that has been dormant in our bodies since childhood.
This leads to a ‘dramatic’ accumulation of plaque and inflammation in the brain – two hallmarks of Alzheimer’s disease.
Chickenpox occurs when the body is first exposed to the varicella zoster virus (VZV), usually as children. Shingles results from subsequent infections.
Researchers used lab-grown brain cells to create a three-dimensional brain to see the impact VZV has on the brain.
They found that it didn’t directly cause the signature changes associated with Alzheimer’s disease.
But it did reactivate the simplex virus (HSV-1), better known for causing cold sores, causing a rapid build-up of harmful proteins.
Study author Dana Cairns, of Tufts University in Massachusetts, said, “It’s a one-two punch of two viruses that are common and mostly harmless.
Catching shingles may raise Alzheimer’s risk by triggering brain chain reaction, scientists warn (file image)
“But the lab studies suggest that if a new exposure to VZV wakes up dormant HSV-1, they could cause problems.”
HSV-1 normal lies dormant in the body and there is strong evidence that it may be linked to dementia.
Air pollution causes dementia, UK government admits for the first time
Air pollution is causing an increase in dementia, the British government has acknowledged for the first time.
Toxic particles in the air from cars and fossil fuels have long been linked to rapidly increasing rates of disease in the UK and the developed world.
Now a large independent review has confirmed the link after analyzing dozens of human studies.
The researchers concluded that it is ‘likely that air pollution can contribute to a decline in mental capacity and dementia in the elderly’.
They believe the main way this happens is through tiny toxic particles that seep into the bloodstream after being inhaled into the lungs.
The pollutants then irritate the blood vessels and disrupt circulation to the brain. This can eventually lead to vascular dementia.
It is also likely that in rare cases very small air pollution particles can cross the blood-brain barrier and directly damage neurons.
But this does not appear to be an important mechanism at the level of air pollution currently in the UK, the report said.
Previous research has found that older people with high levels of the virus in their brains have a much higher risk of Alzheimer’s disease.
Professor Ruth Itzhaki, from the University of Manchester, collaborated with researchers from the Oxford Institute of Population Aging and Tufts University on the latest study.
Researchers created brain-like environments in 6 millimeter wide donut-shaped sponges made of silk protein and collagen.
They populated the sponges with stem cells that grew into neurons and could transmit signals to each other, just like in the brain.
Results showed that neurons in the brain can be infected with VZV, but that alone does not lead to plaque formation and cell death.
Neurons infected with the virus could still function normally.
However, if the cells also harbored HSV-1, there was a dramatic increase in tau and beta-amyloid proteins, strongly linked to dementia.
The neuronal signals also began to slow down.
Professor Itzhaki said: ‘This striking result seems to confirm that infections such as VZV can cause an increase in inflammation in the brain in humans, which can reactivate the dormant HSV-1.
‘The damage in the brain from repeated infections throughout life would eventually lead to the development of AD/dementia.
“This would mean that vaccines could play a greater role than just protecting against a single disease, as they may 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 tend to affect people more often as they get older.
About one in five people who have had chickenpox develop shingles, and most are in their 70s.
Researchers also warn that obesity, smoking, alcohol and head trauma may also increase the risk of Alzheimer’s disease by weakening the immune system and activating dormant HSV1 in the brain.
More than 900,000 people live with dementia in the UK today, expected to rise to 1.6 million by 2040
Alzheimer’s disease is the most common form of dementia.
Current estimates are that about 5.8 million people in the US have the condition, most of whom are over the age of 65.
WHAT IS DEMENTIA? THE KILLER DISEASE THAT DEPRIVES SUFFERING OF THEIR MEMORIES
A GLOBAL CARE
Dementia is an umbrella term used to describe a range of progressive neurological disorders (affecting the brain) that affect memory, thinking, and behavior.
There are many different forms of dementia, with Alzheimer’s disease being the most common.
Some people may have a combination of dementias.
Regardless of which type is diagnosed, each person will experience their dementia in their own unique way.
Dementia is a global problem, but it is most often seen in wealthier countries, where people are likely to live very old.
HOW MANY PEOPLE ARE INVOLVED?
The Alzheimer’s Society reports that there are more than 900,000 people living with dementia in the UK today. This is expected to increase to 1.6 million by 2040.
Alzheimer’s disease is the most common form of dementia, affecting between 50 and 75 percent of diagnosed individuals.
There are an estimated 6 million Alzheimer’s patients in the US. A similar percentage increase is expected in the coming years.
As a person gets older, so does the risk of developing dementia.
Diagnoses are improving, but it is believed that many people with dementia still remain undiagnosed.
IS THERE A CURE?
Currently, there is no cure for dementia.
But new drugs can slow progression, and the sooner it’s noticed, the more effective treatments are.
Source: Alzheimer’s Society