Statins and the risk of dementia

Background Dementia affects an estimated 10% of the population older than 6 5 years. Because vascular and lipid-related mechanisms are thought to have a role in the pathogenesis of Alzheimer's disease and vascular dementia, we did an epidemiological study of the potential effect of HMGCoA (3 hydroxy- 3 methylglutaryl-coenzyme A) reductase inhibitors (statins) and other lipid -lowering agents on dementia, Methods We used a nested case-control design with information derived from 368 practices which contribute to the UK-based General Practice Research Da tabase. The base study population included three groups of patients age 50 years and older: all individuals who had received lipid-lowering agents (LL As); all individuals with a clinical diagnosis of untreated hyperlipidaemia : and a randomly selected group of other individuals. From this base popula tion, all cases with a computer-recorded clinical diagnosis of dementia wer e identified. Each case was matched with up to four controls derived from t he base population on age, sex, practice, and index date of case. Findings The study encompassed 284 cases with dementia and 1 080 controls. Among controls 13% had untreated hyperlipidaemia, 11% were prescribed stati ns, 7% other LLAs, and 69% had no hyperlipidaemia or LLA exposure. The rela tive risk estimates of dementia adjusted for ape, sex, history of coronary- artery disease, hypertension, coronary-bypass surgery and cerebral ischaemi a, smoking and body mass index for individuals with untreated hyperlipidaem ia (odds ratio 0.72 [95% CI 0.45-1.14]), or treated with non-statin LLAs (0 .96 [0.47-1.97], was close to 1.0 and not significant compared with people who had no diagnosis of hyperlipidaemia or exposure to other lipid-lowering drugs. The adjusted relative risk for those prescribed statins was 0.29 (0 .13-0.63; p=0.002). Interpretation Individuals of 50 years and older who were prescribed statin s had a substantially lowered risk of developing dementia, independent of t he presence or absence of untreated hyperlipidaemia, or exposure to non-sta tin LLAs. The available data do not distinguish between Alzheimer's disease and other forms of dementia.