TRAUMATIC BRAIN INJURY INCREASES BETA-AMYLOID PEPTIDE 1-42 IN CEREBROSPINAL-FLUID

The p-amyloid peptides, A beta 1-42 and A beta 1-40, were quantified i n ventricular CSF taken daily for up to 3 weeks from six individuals w ith severe traumatic brain injury (TBI). There was considerable interi ndividual variability in the levels of A beta peptides, but in general A beta 1-42 levels equalled or exceeded those of A beta 1-40. Averagi ng the daily totals of our trauma cohort revealed that the levels of A beta 1-42 and A beta 1-40 rose after injury, peaking in the first wee k and then declining toward control levels over the next 2 weeks. A be ta 1-42 levels were on average two to three times higher in the trauma cohort than in CSF from nontrauma samples. Compared with nontrauma sa mples, the A beta 1-40/A beta 1-42 ratio decreased about fivefold in t he trauma patients, further indicative of increased A beta 1-42 levels . The ratio remained low at all time points studied. No change was mea sured in the levels of beta-amyloid precursor protein during the same interval, These results suggest that A beta 1-42 becomes elevated in t he CSF after severe brain trauma.