From the Guidelines
There is a relationship between dementia and traumatic brain injury (TBI) from concussion, with repeated concussions or TBIs increasing the risk of developing dementia later in life, particularly a condition called chronic traumatic encephalopathy (CTE) 1.
Key Findings
- Repeated concussions or TBIs can cause cumulative damage to the brain, leading to an increased risk of dementia, particularly CTE 1.
- A single mild concussion typically does not lead to dementia, but multiple concussions or more severe TBIs can cause significant damage to the brain 1.
- The relationship between TBI and dementia works through several mechanisms, including the accumulation of abnormal proteins like tau and amyloid beta, chronic inflammation, damage to axons, and disruption of normal brain function 1.
At-Risk Populations
- Athletes in contact sports, such as football, boxing, and hockey, are at highest risk of developing CTE and dementia due to repeated head injuries 1.
- Military veterans exposed to blast injuries and individuals with a history of multiple head injuries are also at increased risk of developing dementia and CTE 1.
Prevention and Management
- Prevention is crucial through proper concussion management, including complete cognitive and physical rest after injury, gradual return to activities, and avoiding additional head impacts before full recovery 1.
- Protective equipment and rule changes in sports have also been implemented to reduce concussion risk and its potential long-term consequences 1.
Evidence Quality
- The evidence for the relationship between TBI and dementia is based on Class III studies, which have limitations in terms of methodology and generalizability 1.
- However, the consistency of findings across multiple studies and the biological plausibility of the relationship support the conclusion that there is a link between TBI and dementia 1.
From the Research
Relationship Between Dementia and Traumatic Brain Injury (TBI) from Concussion
- There is evidence to suggest a relationship between dementia and traumatic brain injury (TBI) from concussion, as studies have found an association between recurrent concussion and late-life cognitive impairment, mild cognitive impairment (MCI), and dementia 2, 3.
- A study of retired professional football players found that those with three or more reported concussions had a fivefold prevalence of MCI diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion 2.
- Another study found that older adults who received a statin after a concussion had a 13% reduced risk of dementia compared with patients who did not receive a statin 4.
- However, not all studies have found a consistent association between concussion and dementia, and some have suggested that the relationship may be complex and influenced by other factors, such as genetic risk and co-morbid pathology 5, 6.
Concussion Severity and Recovery Metrics
- A study using Alzheimer's disease polygenic risk scores (PRS) found that higher PRS was associated with longer injury to return to play (RTP) in young adults, but there were no other consistently significant effects on concussion severity or recovery metrics 6.
- Another study found that military personnel who sustained concussions during service were at elevated risk for long-term neurodegenerative outcomes, including memory loss, mild cognitive impairment, and dementia, but not early-onset dementia 3.
Limitations and Future Directions
- The current evidence is largely based on observational studies and retrospective analyses, and more prospective studies with long-term follow-up are needed to fully understand the relationship between concussion and dementia 2, 5, 4, 3, 6.
- Further research is also needed to explore the potential mechanisms underlying the association between concussion and dementia, including the role of genetic risk, co-morbid pathology, and other factors 5, 6.