Wolozin B et al. (2007) Simvastatin is associated with a reduced incidence of dementia and Parkinson's disease. BMC Med 5: 20

Previous studies have suggested that cardiovascular problems are major risk factors for the development of dementia, and that statins—drugs used to treat cardiovascular problems—might, therefore, reduce the incidence of dementia. Conflicting results in the literature, however, led Wolozin and colleagues to suggest that different statins might affect the incidence of dementia to different extents.

The researchers analyzed information from the decision support system of the US Veterans Affairs database on 727,128 patients taking simvastatin, 53,869 taking atorvastatin, and 54,052 taking lovastatin. All patients were over 64 years of age. Cox proportional hazard models were used to investigate the associations of these different agents with dementia.

The results showed that, after adjustment for factors associated with dementia or Parkinson's disease, including age, known risk factors, and Charlson comorbidity index score, use of simvastatin was associated with a significant reduction in incident dementia and incident Parkinson's disease (P <0.0001). Use of atorvastatin was associated with a modest reduction in incident dementia, which was of borderline significance after adjustment for age (P = 0.11), but not after adjustment for other comorbidities. Lovastatin use, on the other hand, was not associated with a reduction in dementia.

The authors concluded that further investigation is warranted to establish whether these findings are attributable to the biological actions of the drugs or to an unanticipated statistical bias in the database.