People whose parents have Alzheimer's disease are more likely to show signs of the disease before actual symptoms appear, according to a new study published in an online issue of Neurology.

Researchers took brain scans of people, and found that those whose parents were both diagnosed with the disease were more likely to have evidence of the disease, including plaque buildup, on their brains decades before symptoms might appear.

Researchers studied 52 people without Alzheimer's disease between 32 and 72 years old and gave them PET and MRI brain scans. Participants were split into four groups: those whose mother had Alzheimer's disease, father with the disease, both parents with the disease, or no family history of the disease.    

People with both parents who had Alzheimer's disease showed more severe abnormalities in the brain volume than the other three groups.