Background: Statins are well-known for their cardiovascular benefits. However, the cognitive effects of statins are not well understood. We hypothesized that individuals with preexisting dementia would be more vulnerable to statin-related cognitive effects.

Objective: The aim of this study was to evaluate the impact on cognition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor (statin) discontinuation and rechallenge in individuals with Alzheimer's dementia (AD) on statins at baseline.

Methods: A 12-week prospective, open-label study was conducted in a geriatric clinic setting. Eighteen older subjects underwent a 6-week withdrawal phase of statins followed by a 6-week rechallenge. The primary outcome measure was cognition, measured by the Mini-Mental State Examination (MMSE); secondary outcome measures were the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery, Activities of Daily Living (ADL) scale, Instrumental ADL (IADL) scale, and fasting cholesterol. The change in outcome measures was assessed using repeated-measures ANOVA and paired t tests.

Results: At the end of the intervention, there was a significant difference across time for MMSE score (P = 0.018), and total cholesterol (P = 0.0002) and a trend toward change across time for ADL (P = 0.07) and IADL (P = 0.06) scale scores. Further analyses using paired t tests indicated improvement in MMSE scores (Δ1.9 [3.0], P = 0.014) with discontinuation of statins and a decrease in MMSE scores (Δ1.9 [2.7], P = 0.007) after rechallenge. Total cholesterol increased with statin discontinuation (P = 0.0003) and decreased with rechallenge (P = 0.0007). The CERAD score did not show a change across time (P = 0.31). There was a trend toward improvement in ADL (P = 0.07) and IADL (P = 0.06) scale scores with discontinuation of statins, but no change with rechallenge.

Conclusions: This pilot study found an improvement in cognition with discontinuation of statins and worsening with rechallenge. Statins may adversely affect cognition in patients with dementia.