Low cerebrospinal fluid beta-amyloid 42 in patients with acute bacterial meningitis and normalization after treatment

CSF-A beta 42 may be a marker of Alzheimer's disease (AD). A decreased leve l of CSF-A beta 42 is consistently found in AD and has been suggested to be related to the deposition of amyloid plaques in the brain. However, low CS F-A beta 42 levels have also been found in disorders devoid of plaques, for instance Creutzfeldt-Jakob disease. To examine if the level of A beta 42 i n CSF is related to inflammatory processes, we studied CSF-A beta 42 levels in eight patients with acute purulent bacterial menignitis, 10 patients wi th acute viral meningitis and 18 age-matched controls. In acute purulent ba cterial meningitis, the CSF-A beta 42 level was markedly reduced (28% of th at in controls, P < 0.0001), whereas no change was found in viral meningiti s. After successful treatment of bacterial meningitis, the CSF-A beta 42 le vel increased (P < 0.05 compared to baseline) and did no longer differ from that in controls (ns). The decrease could not be explained by interference with high protein levels, since addition of increasing volumes of serum di d not influence the CSF-A beta 42 levels. Our findings suggest that the red uction in CSF-A beta 42 found in bacterial meningitis is not a direct conse quence of the inflammatory process. The cause may be disturbance of the cle arance of A beta 42 from the brain. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.