A Dutch study has revealed that as many as 13% of healthy adults may have some type of undiagnosed abnormality in the brain.
The researchers reached this conclusion after examining MRI (magnetic resonance imaging) scans of 2,000 volunteers and say the abnormalities are often harmless.
The researchers, led by Dr. Meike Vernooij, an associate professor of radiology at the Erasmus MC University Medical Center in Rotterdam, found that 7.2 percent of the scans showed evidence of a brain clot, 1.8 percent had cerebral aneurysms, and 1.6 had benign brain tumors.
The clots however were too small to produce symptoms and seemed to be more common with age; the volunteers were between the ages of 46 and 97, with an average age of 63 years and, prior to the MRI, had no known brain abnormalities.
MRI's give a detailed picture of the physical brain structure and the study is important as brain scans are more and more commonly used, so doctors interpreting the scans need to know whether to be concerned if they see something unexpected.
Almost 2 percent showed a brain aneurysm, which is a bulge in a blood vessel that can burst if it becomes too big, causing a stroke, but of the 35 aneurysms, 32 were so small, follow-up medical treatment was not suggested.
The younger volunteers were just as likely to have them as older ones.
The scans also uncovered 32 tumors and all but one were benign and thirteen people had more than one abnormality.
The researchers say as MRI scans become more sensitive, the number of small brain abnormalities detected will increase and doctors will need to know which ones can be disregarded.
The study is published in the current issue of the New England Journal of Medicine.