TELEGRAPH [UK] – Alzheimer’s may sometimes be caused by a herpes virus that travels from the gut to the brain, scientists believe.
Experts in the US found evidence of infections in the post-mortem brains of people who had died with the disease, and think it may be to blame for up to 45 per cent of cases.
The virus implicated, cytomegalovirus or HCMV, is one of nine herpes viruses, although it is not considered a sexually transmitted disease.
Most people are exposed to HCMV in the first few decades of life, but it generally lives harmlessly in the gut in a dormant state.
However, scientists believe that in some people, the virus may linger in an active state travelling to the brain via the vagus nerve – an important communication highway between the gut and the brain.
…article continued below
– Advertisement –
Once there, the virus appears to trigger the immune system in a way that may contribute to the formation of amyloid plaques and tau tangles that prevent brain cells communicating.
“We think we found a biologically unique subtype of Alzheimer’s that may affect 25 to 45 per cent of people with this disease,” said Dr Ben Readhead, an expert in neurodegenerative disease at Arizona State University.
“This subtype of Alzheimer’s includes the hallmark amyloid plaques and tau tangles – microscopic brain abnormalities used for diagnosis – and features a distinct biological profile of virus, antibodies and immune cells in the brain.”
Post-mortem brains from Alzheimer’s patients showed they had more immune cells implicated in inflammation than people without the disease, while the virus was found in the intestines and spinal fluid contained antibodies against HCMV.
The team also found HCMV within the vagus nerve of the same people, suggesting that is how the virus reaches the brain.
…article continued below
– Advertisement –
HCMV is usually passed through exposure to bodily fluids and spread only when the virus is active …