Fluid channels in the brain that help to remove waste could be impaired after traumatic injury, promoting cell death.

After injury, brain cells release a protein called tau, which accumulates as tangles and is associated with neurodegeneration and dementia. Jeffrey Iliff at the Oregon Health and Science University, Portland, and his colleagues showed that tau is cleared from young healthy mouse brains along the 'glymphatic pathway', channels that wash out waste from the brain.

The authors found that after traumatic injury, the pathway's performance decreased by about 60%. It was reduced even further in injured mice in which a gene important for the pathway, aquaporin-4, had been knocked out. These mice developed tau tangles and performed less well in cognitive tests.

J. Neurosci. 34, 16180–16193 (2014)