Concussions involving at least a momentary loss of consciousness have been linked to Alzheimer's-associated plaque in the brain, which are sticky protein pieces called beta-amyloid that clump around surrounding nerve cells.
Researchers from Mayo Clinic studied the brain scans of the residents, aged 70 or older, of Olmsted County in Minnesota. Of these people, 448 had no memory-related problems and 141 had mild cognitive impairment -- memory and thinking problems. All were then asked if they'd had any brain injury that involved loss of consciousness.
Among the 448 without cognitive impairment, 17 percent reported a brain injury. Among those with impairment, 18 percent had experienced a concussion or head trauma.
The findings, published in the Decmeber issue of Neurology, showed that there were no differences in the brain scans of people with no memory-related issues whether or not they had experienced head trauma..
But among people who had cognitive impairment, those who had experienced brain injury exhibited amyloid plaques 18 percent more than those without any brain injury.
"Our results add merit to the idea that concussion and Alzheimer's disease brain pathology may be related," said study author Michelle Mielke of Mayo Clinic. "However, the fact that we did not find a relationship in those without memory and thinking problems suggests that any association between head trauma and amyloid is complex."