Concussions increase risk of brain atrophy in professional football players later in life, according to a recent study Live Science reported.

Researchers at the University of Texas Southwestern Medical Center and the Center for BrainHealth at University at Dallas found that National Football League (NFL) players who lost consciousness due to concussion during their playing days showed key differences in brain structure later in life. The hippocampus, a part of the brain involved in memory, was found to be smaller in 28 former NFL players as compared with a control group of men of similar age and education.

"This is a preliminary study, and there is much more to be learned in the area of concussion and cognitive aging," Dr. Munro Cullum, co-author of the study and a professor of Psychiatry and Neurology and Neurotherapeutics at UT Southwestern, said in a statement. "While we found that aging individuals with a history of concussion and loss of consciousness showed smaller hippocampal volumes and lower memory test scores, the good news is that we did not detect a similar relationship among subjects with a history of concussion that did not involve loss of consciousness, which represents the vast majority of concussions."

For the study, a team of neurologists and neuropsychologists compared the relationship between hippocampal volume, memory performance, and concussion severity, Medical Daily reported.

Some of the retired NFL players also met criteria for Mild Cognitive Impairment (MCI), a condition that typically affects memory and may lead to dementia. The findings were more pronounced among those who experienced more severe concussions.

The former players ranged from 36 to 79 years old, with a mean age of 58. Twenty-one healthy men of similar age, educational level, and intelligence with no history of concussion or professional football experience served as control subjects.

Researchers said the results do not explain why the hippocampus was smaller in the athletes who suffered more serious concussions. Some shrinkage is a part of the normal aging process but the reduction is accentuated in MCI and was even more notable in those MCI subjects with a history of concussion accompanied by loss of consciousness.

The findings are detailed in JAMA.