ApoE as a prognostic factor for post–traumatic coma

Nicoll et al. explored the association between the epsilon 4 allele of apolipoprotein E (apo E) and fatal head injuries in the February issue of Nature Medicine. Deposition of amyloid beta -protein (A beta ) in the brain occurs in approximately one-third of individuals who die shortly after a severe brain injury, and the frequency of apoE- epsilon 4 allele was found to be significantly higher in those head-injured individuals with A beta deposits. Moreover, patients with apoE- epsilon 4 allele who survive head trauma have a tenfold increased risk of Alzheimer's disease. We have studied the apoE genotype in a small number of patients with prolonged post-traumatic unawareness and have found a higher frequency of the apoE- epsilon 4 allele in those individuals who did not recover consciousness.