Methods: FDA database MedWatch reports of atorvastatin-associated adverse events were searched for terms that included the word amnesia. This search revealed reports listed as transient amnesia, transient global amnesia, wandering amnesia, anterograde amnesia, dissociative amnesia, and retrograde amnesia. No reports were uncovered using the terms memory loss, memory disturbance, or memory disruption; yet memory impairment revealed multiple reports. Searches were directed at only serious cognitive events. Minor events such as forgetfulness or confusion were not sought, and it is possible that we missed an occasional serious event listed under a mild symptom. The well-known Naranjo ADR Probability Scale was applied to 50 randomly selected case reports of Lipitor-associated cognitive dysfunction.
Results: Six hundred and sixty-two MedWatch reports were received of atorvastatin-associated cognitive impairments. Of these, 399 were cases of amnesia, and 263 were cases of memory impairment. The number of reports per year increased from 1997 through 2006. Random analysis of individual MedWatch reports demonstrated that most were definitely or probably caused by atorvastatin. The average atorvastatin dosage of cases in 1997-2001 was 15 mg/day, whereas the average dosage in 2006 was 22 mg/day. Earlier research suggests that the number of MedWatch reports for statin-linked adverse events greatly underestimates the scope of the problem. Other research suggests that statin drugs may cause subclinical yet important cognitive impairments in all patients receiving statins.
Conclusion: The findings of the present study, coupled with earlier research, demonstrate the urgent need for further research regarding the frequency and severity of cognitive impairments in patients receiving statin drugs.