(CNN) – New evidence suggests a common virus may play a role in who develops Alzheimer's disease.
In a study published Thursday in the journal Neuron, researchers said they've found strong evidence to suggest two strains of the human herpes virus may contribute to the disease.
The researchers looked at data on 622 brains from people with signs of Alzheimer's and 322 from people who did not seem to be affected by it.
The brains with Alzheimer's had levels of the herpes virus that were up to twice as high as in people who did not have the disease.
The scientists caution that people shouldn't be alarmed by their discovery, because this particular set of herpes viruses is common.
Research shows about 90 percent of adults have been exposed to the herpes virus by age 50. Not all of them go on to develop dementia.
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