Levels of ApoE in cerebrospinal fluid are correlated with Tau and 24S-hydroxycholesterol in patients with cognitive disorders.

Evidence was recently presented from in vitro studies that 24S-hydroxycholesterol acts as a signalling molecule inducing apoE-mediated cholesterol efflux from astrocytoma cells, and that there is a direct effect of the oxysterol on apoE transcription, protein synthesis and secretion. Consistent with this mechanism, a significant correlation is demonstrated here between levels of apoE and 24S-hydroxycholesterol in cerebrospinal fluid from patients with Alzheimer's disease and patients with mild cognitive impairment. Such a correlation was not found in control patients. There was no correlation between levels of apoE and cholesterol in cerebrospinal fluid from controls. The results are consistent with a close coupling between release of 24S-hydroxycholesterol and apoE secretion under conditions with neuronal degeneration. The levels of apoE in cerebrospinal fluid were also correlated to the levels of Tau and the possibility is discussed that the level of apoE in cerebrospinal fluid may be used as a marker of neurodegeneration.