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After analysing data from three brain banks, researchers from the US have reported that human herpes viruses (HHV) are more abundant in the brains of patients with Alzheimer disease than in healthy controls, and suspect that they may play a role in regulatory genetic networks that lead to the disease. Published in Neuron, the study lends support to the hypothesis that viruses are involved in Alzheimer disease, and suggests potential new paths for treatment. The researchers analysed data from three major brain banks, courtesy of the National Institutes of Health’s Accelerating Medicines Partnership – Alzheimer’s Disease (AMP-AD) consortium, which allowed them to look at raw genomic data for large numbers of patients with Alzheimer disease. They constructed, mapped and compared regulatory gene networks on multiple levels, looking at DNA, RNA and proteins in areas of the brain implicated in Alzheimer disease. They found that human herpes virus DNA and RNA were more abundant in the brains of those diagnosed post mortem with the disease and that their abundance was correlated with clinical dementia scores. The two viruses they found to be most strongly associated with Alzheimer disease, HHV-6A and HHV-7, were not as abundant in the brains of those with other neurodegenerative disorders. When they constructed networks that modelled how the viral genes and human genes interacted, they found that the viral genes were regulating and being regulated by human genes, including genes associated with increased Alzheimer risk.