A β42is the predominant form of amyloid b protein in the brains of shortterm survivors of head injury

FATAL head injury results in the formation of diffuse parenchymal deposits of amyloid β-protein (Aβ) in the brains of approximately 30 of individuals. We used carboxyl terminal-specific antisera to examine the exact nature of these deposits in paraffin sections of neocortex from seven head-injured patients. Immunostaining for Aβ42was observed in all parenchymal deposits whereas staining for Aβ40, the form of the protein which predominates in serum and cerebrospinal fluid, was seen in only a small proportion of deposits. The relative paucity of Aβ40suggests that post-traumatic deposits do not arise as a result of passive leakage from damaged cerebral blood vessels but are similar to the early Aβ42parenchymal deposits seen in Down's syndrome and Alzheimer's disease.