Scientists in the US have found an association between two forms of the human herpes virus and Alzheimer’s disease. The findings are published today (Thursday 21 June) in the scientific journal Neuron.
Dr David Reynolds, Chief Scientific Officer of Alzheimer’s Research UK, said:
“These findings point to an association between two forms of the herpes virus and Alzheimer’s, but they don’t tell us that these viruses cause the disease.
“Previous studies have suggested that viruses might be linked with Alzheimer’s, but this detailed analysis of human brain tissue takes this research further, indicating a relationship between the viruses and the activity of genes involved in Alzheimer’s, as well as brain changes, molecular signals, and symptoms associated with the disease. This was a well-conducted study and the authors’ findings were supported by evidence drawn from three independent sources of donated brain tissue.
“The viruses highlighted in this study are not the same as those that cause cold sores, but much more common forms of herpes that are among the many viruses that nearly everyone carries, and which don’t typically cause any problems. While the findings indicate a link between the activity of these viruses and Alzheimer’s, they don’t tell us whether they contribute to the development of the disease, help the brain to cope with the disease, or just occur alongside Alzheimer’s-processes without having an impact on the health of the brain.
“In an experiment involving mice, the researchers reproduced an effect of one of these viruses – reduced activity of a gene called Mir155 – finding that it led to higher levels of the hallmark Alzheimer’s protein, amyloid. The authors suggest their findings in mice support the idea of viral activity contributing to the development of Alzheimer’s, but their analysis of human brain tissue doesn’t give conclusive evidence about cause and effect.”
“As almost everyone carries these viruses, the findings don’t provide any insight into an individual’s risk of Alzheimer’s, but they do highlight a need for future studies to explore the nature of the link. This study in no way suggests that Alzheimer’s disease is contagious or can be passed from person to person like a virus.”