Clioquinol for the treatment of Alzheimer's Disease

Alzheimer's disease (AD) may result in senile plaques being formed outside the brain as accumulation of beta-amyloid (Ass).

To evaluate the efficacy of clioquinol for the treatment of cognitive impairment due to Alzheimer's disease.

The Cochrane Dementia and Cognitive Improvement Group's Specialized Register was searched on 20 May 2005 using the terms clioquinol and PBT1. The Register contains records from major health care databases and many ongoing trial databases and is updated regularly. The Internet was searched using the term: clioquinol PBT1 Alzheimer*.

Randomised double-blind trials in which treatment with clioquinol was administered to participants with Alzheimer's disease in parallel group comparison with placebo are included.

Two reviewers (RM, LJ) independently assessed the quality of trials according to the Cochrane Collaboration Handbook. The primary outcome measures of interest were cognitive function (as measured by psychometric tests) and global impression. The secondary outcome measures of interest were in the following areas: quality of life, functional performance, effect on carer, safety and adverse effects, and death.

There was one included trial of clioquinol compared with placebo in 36 patients.

It is not clear from the trial that clioquinol shows any positive clinical result on patients with AD. The two statistically significant positive results were seen for the more severely affected subgroup of patients. This effect was not maintained at the 36 week end-point. The sample size was small. Details of randomisation procedure or blinding were not reported. Further studies are needed to evaluate the potential for clioquinol as a treatment of AD. Trials of longer duration are also required, particularly because information about the side-effects of long-term use of clioquinol is limited.