Statins and cognition: what can we learn from existing randomized trials?
BACKGROUND
Statins are being developed as treatments for Alzheimer's dementia based on evidence from preclinical and observational studies. However, cholesterol plays an integral role in cell membrane signal transduction and suboptimal cholesterol level could potentially impair neuronal function. Additionally, results of observational nonrandomized studies may have been affected by treatment bias.


METHODS
We performed a systematic literature review in MEDLINE from January 1966 to July 2004 and included published prospective, randomized, and placebo-controlled human studies that examined the cognitive effects of statins.


RESULTS
Nine studies with sample sizes ranging from 22 to 20,000 and duration of 3 weeks to 5 years, met criteria for review. Study populations and cognitive outcomes varied. Four studies were >6 months or longer. Overall, none of these studies reported finding a positive benefit for any statin on cognition in non-demented subjects although there was inconsistent evidence for acute cognitive worsening in some studies.


CONCLUSIONS
While statins intuitively have appeal for the prevention or treatment of dementia, any conclusions about their efficacy should await more definitive evidence from on-going prospective clinical trials.
Xiong
Glen L
GL
Department of Psychiatry, Duke University Medical Center, Durham, NC 27710, USA. xiong001@mc.duke.edu
Benson
Aaron
A
Doraiswamy
P Murali
PM
D000544:Alzheimer Disease / Q000517:prevention & control*; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000924:Anticholesteremic Agents / Q000627:therapeutic use*; D001921:Brain / Q000187:drug effects; D003072:Cognition Disorders / Q000517:prevention & control*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use; D006937:Hypercholesterolemia / Q000150:complications / Q000188:drug therapy*; D017063:Outcome Assessment, Health Care; D016032:Randomized Controlled Trials as Topic
D016229:Amyloid beta-Peptides; D000924:Anticholesteremic Agents; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors