Repeated Head Impacts
There is growing concern about the long-term effects on the brain of people who experience multiple or repeated head impacts. Repeated head impacts include not only head impacts that lead to a mild TBI or concussion, but also head impacts that do not cause the person to feel symptoms after a hit to the head. Collisions while playing sports is one way a person may experience repeated head impacts.
A person with a history of repeated mild TBIs or concussions may:
- Experience a longer recovery or more severe symptoms1
- Have long-term problems, including ongoing problems with concentration, memory, headache, and occasionally, physical skills, such as keeping one’s balance1
Studies are ongoingexternal icon to learn if getting multiple head impacts that do not cause a person to feel symptoms affect the brain over time.
Chronic Traumatic Encephalopathy (CTE) is a brain disease
CTE is a brain disease that can only be diagnosed after death. It has been linked to specific changes in the brain that affect how the brain works.
Understanding of the causes of CTE is currently limited.
- Researchers do not know the number and types of head impacts that increase the risk for CTE
- It is possible that biological, environmental, or lifestyle factors could also contribute to the brain changes found in people with CTE diagnosed after death2,3
- There are research gaps about the causes of CTE, its symptoms, and how it affects the brain4
- Evidence is limited on the role of genetics, a person’s medical history, and other factors (such as environmental or lifestyle factors) as risk factors for CTE
The National Institutes of Health (NIH) launched a major program to:
- Better understand CTE
- Its causes, and
- How to diagnose it among living persons
Learn more about NIH efforts around CTEexternal icon.
Occasional hits to the head do not cause CTE
Occasional hits to the head, such as the bumps and tumbles that children experience when learning to walk, do not cause CTE.
- Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Report to Congress on traumatic brain injury in the United States: Epidemiology and rehabilitationpdf icon. Atlanta (GA): Centers for Disease Control and Prevention; 2015.
- Iverson G, Gardner A, McCrory P, Zafonte R, Castellani R. A critical review of chronic traumatic encephalopathy. Neurosci Biobehav Rev. 2015;56:276-293.
- Iverson GL, Keene CD, Perry G, Castellani RJ. The need to separate Chronic Traumatic Encephalopathy neuropathology from clinical features. J Alzheimers Dis. 2018;61(1):17-28.
- Asken BM, Sullan MJ, DeKosky ST, Jaffee MS, Bauer RM. Research gaps and controversies in chronic traumatic encephalopathy: a review. JAMA Neurol. 2017;74(10):1255-1262.