H. Kölsch*, D. Lütjohann**, K. von Bergmann**, R. Heun*

*Department of Psychiatry. **Department of Clinical Pharmacology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany. Correspondence: H. Kölsch, Department of Psychiatry, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany, tel.: +49-228-287-9398, fax: +49-228-287-6383. E-mail: heike.koelsch@ukb.uni-bonn.de

Studies on Alzheimer's disease (AD) revealed that cholesterol metabolism might be involved in the pathogenesis of this neurodegenerative disorder. The apolipoprotein E4 genotype is a known risk factor in AD. Elevated serum cholesterol concentrations are detected in patients with AD and two recent epidemiological studies have indicated that treatment with inhibitors of cholesterol synthesis (statins) decrease the incidence of AD. 24R- and 24S-Hydroxycholesterol, the major cholesterol elimination product of the brain, possess neurotoxic effects in vitro, and increased concentrations of 24S-hydroxycholesterol have been detected in patients from our department, suggesting a role for this oxysterol in the pathogenesis of AD. This review will give a brief overview on the relevance of 24S-hydroxycholesterol as a possible risk factor and diagnostic state marker for AD.

Keywords: Alzheimer's disease, cholesterol, apolipoprotein E, 24S-hydroxycholesterol, neurotoxicity, diagnostic marker.