Alzheimer's Association Statement on a Study Of Clioquinol Targeting Aß Amyloid Deposition and Toxicity In Alzheimer's Disease

Alzheimer's Association
Monday, 15 December 2003

From Archives Of Neurology, December 2003

William Thies, Ph.D., vice president, Medical and Scientific Affairs, Alzheimer's Association.

This study follows up on basic and animal research showing that an antibiotic, clioquinol, can prevent, and possibly disperse, clumps of the substance called amyloid that builds up in the brain of people with Alzheimer's disease. The trial showed some promising results in stabilizing cognitive decline. However, the sample size is very, very small (36 total subjects, 16 received the drug and completed the trial) and the effect is not dramatic.

With the caveat that this study involved a very small number of participants, the Alzheimer's Association believes that the lack of toxicity and possible effectiveness warrant further investigation in this area.

We need to test the amyloid hypothesis – currently the leading school of thought regarding the cause of Alzheimer's disease. The main importance of studies like this is to attempt to prove the principle that amyloid-lowering agents can stabilize or possibly even reverse cognitive decline in Alzheimer's. A variety of different strategies are being utilized to test the safety and effectiveness of anti-amyloid therapies.

If amyloid "plaque-buster" drugs are effective in preventing or treating Alzheimer's, this may solve the longstanding, often heated controversy surrounding the issue of whether amyloid really causes Alzheimer's or is instead an innocent bystander. A positive result would lead to a redoubled effort at more and better "anti-amyloid" medicines; a negative result will send the world's Alzheimer experts back to "square one."

One notable result of this study is that no one got sick from the drug. Clioquinol has been shown to cause optic nerve and spinal cord damage as a side effect, especially in people of Japanese ancestry. According to the researchers, "Clioquinol-associated optic neuropathy was suspected in 1 subject with a prominent history of eye disease, but a direct causal link remains uncertain." Twenty-seven study participants agreed to participate in an open-label extension of the trial. Ten of these people have been taking the drug for more than 18 months and have not experienced these side effects.

This study was funded, in part, by the Alzheimer's Association.

The Alzheimer's Association is the world leader in Alzheimer research and support. Having awarded more than $150 million to nearly 1,300 projects, the Alzheimer's Association is the largest private funder of Alzheimer's disease research. The Association's vision is a world without Alzheimer's disease. For more information about Alzheimer's disease, research and treatments, please call 800-272-3900.

An attempt to replicate and extend this study in a trial of 80 patients in the United States is being contemplated, providing that sufficient safeguards against the side effects can be put into place. The replication trial will be based in Philadelphia under the direction of Drs. Sam Gandy and Barry Rovner, both at the Farber Institute for Neurosciences of Thomas Jefferson University. Dr. Gandy is vice chair of the Alzheimer's Association's Medical & Scientific Advisory Council.

"Metal-Protein Attenuation with Iodochlorhydroxyquin (Clioquinol) Targeting a Amyloid Deposition and Toxicity in Alzheimer Disease," by Ritchie, et al, appears in the December 2003 issue of Archives of Neurology.

For more information, or to contact Alzheimer's Association, see their website at: www.alz.org

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