Take extra care of your health if you suffer concussions, skull fractures or scalp wounds, as a study has found that head injuries almost double a man's risk of developing dementia.
Researchers from the University of Maryland in the US showed that the inflammation caused by traumatic brain injury can spread and cause long-lasting damage.
The findings indicated that the risk is particularly high for men aged between 41 and 56.
This could help guide treatment of the injuries, whose severity is often difficult to gauge.
They also found that exposing the inflammatory microparticles to a compound called PEG-TB could neutralize them.
This opens up the possibility of using that compound or others to treat traumatic brain injury (TBI), and perhaps even other neurodegenerative diseases.
A growing swell of research has shown that chronic inflammation leads to progressive cell loss after TBI.
To investigate the lingering impact of inflammation, lead researcher Alan Faden focused on microparticles produced by inflammatory brain cells.
The results suggested that microparticles can activate normal immune cells, making them potentially toxic to brain neurons.
They are released from cells known as microglia, immune cells that are common in the brain.
After an injury, these cells often go into overdrive in an attempt to fix the injury.
The researchers looked at mice who had a traumatic brain injury, and saw prolific spreads of microparticles in the blood.
They were able to easily track the origin of these microparticles, since every cell has a distinct fingerprint.
The results potentially provide a new conceptual framework for understanding brain inflammation and its relationship to brain cell loss and neurological deficits after head injury.
Faden noted that brain inflammation can trigger more inflammation at a distance through the release of microparticles may offer novel treat ment targets for a number of important brain diseases.
The researchers explained that the microparticles in the blood have the potential to be used as a biomarker - a way to determine how serious a brain injury may be.
The research appears in journal of PLoS Medicine.