Alzheimer's link to herpes virus in brain, say scientists

Research reveals strains of virus more abundant in brains with early stage of disease, though uncertainly whether virus is a trigger or a symptom

The presence of viruses in the brain has been linked to Alzheimer's disease in research that challenges conventional theories about the onset of dementia.

The results, based on tests of brain tissue from nearly 1,000 people, found that two strains of herpes virus were far more abundant in the brains of those with early-stage Alzheimer's than in healthy controls. However, scientists are divided on whether viruses are likely to be an active trigger, or whether the brains of people already on the path towards Alzheimer's are simply more vulnerable to infection.