Commonly-used cholesterol-lowering drugs known as statins can block damage by an Alzheimer's-associated protein in neurons and blood vessels, according to a study by University of South Florida researchers.
The researchers looked at the biochemical effects of statins in reducing damage from Alzheimer's disease. Their study is published in this month's issue of the journal Atherosclerosis.
"Statins block the vasoconstrictive effect of the A-beta protein - a critical protein involved in Alzheimer's disease pathology," said Dr Daniel Paris, lead author of the study and an assistant professor at the USF Roskamp Institute. "These drugs appear to have anti-inflammatory properties, independent of their benefit in lowering cholesterol, that may help protect against dementia."
The risk of developing Alzheimer's disease has been shown to be reduced in populations treated with statins, although the reason is unclear. Other studies indicate that high cholesterol or other cardiovascular conditions also increase the risk for Alzheimer's disease.
The researchers, searching for clues to understand the preventive action of statins, were struck by the similar effects of cholesterol and the A-beta protein (Aß) in blood vessels. Both compounds promote the constriction of blood vessels through a similar mechanism. They hypothesised that the same drugs that inhibit the production of cholesterol might affect Aß's stimulation of inflammatory substances that result in blood vessel constriction.
The researchers studied the effects of two statins most commonly used to treat high cholesterol - mevinolin (lovastatin) and mevastatin (compactin).
Aß appears to be toxic to human neuronal cells cultured in the laboratory. But, when these same neurons were treated with mevastatin, the neurotoxicity normally induced by Aß was prevented, the researchers found.
The researchers also looked at the effect of both statins mevinolin and mevastatin on the constriction of laboratory-prepared aortic arteries from rats. They observed that the statins opposed the Aß protein's propensity to cause blood vessels to constrict.
Furthermore, Dr Paris said, this prevention of vessel constriction appears to be due to the general anti-inflammatory properties of the statins, and is unrelated to the biochemical mechanism used by the drugs to reduce cholesterol production. In other words, statins may protect the vessels by opposing inflammatory substances triggered by Aß.
The researchers are further testing the effectiveness of statins to prevent or slow the progression of Alzheimer's disease in a mouse model for the neurodegenerative disease.