(NBC) – Childhood viruses that infect almost everyone and lie dormant in the body for life might be involved in Alzheimer’s disease, researchers reported Thursday.

They found that viruses called human herpes virus 6 (HHV-6) and HHV-7 were more abundant in the brains of people who died with Alzheimer’s.

Their findings add to a controversial theory that viruses might play a role in starting or fueling Alzheimer’s, a progressive, incurable brain disease that robs people of their personalities, memory and ability to care for themselves.

But the findings mean little — yet — for efforts to find a cure.

“People shouldn’t call their doctors and ask for the virus drug. That won’t be useful yet,” said Alzheimer’s disease specialist Dr. Sam Gandy of Mount Sinai Hospital, who helped lead the study team.

“To be clear, it does not prove the idea that viruses causes Alzheimer’s. It shows that there is a link,” said Keith Fargo, scientific director of the Alzheimer’s Association, who was not involved in the work.

Theories have abounded for decades that viruses might be involved in Alzheimer’s, especially herpes viruses, which have a special affinity for nerve cells.

Herpes viruses, which cause permanent, lifelong infections, can re-activate when people’s immune systems are weakened, so it’s never been clear if the viruses were causing disease or just taking advantage of the disease process to replicate.

Gandy and colleagues looked at data from brains donated by peoples’ families after they died. They analyzed gene sequences taken from the brains — both genes of the patients and of any viruses that happened to be in their brains.

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