Memory Loss & the Brain

A free radical is a molecule with one missing electron. Free radicals are a normal by-product of the body's metabolism of oxygen. And, normally, these free radicals serve important functions, such as helping the immune system fight off disease. However, too many free radicals can start to cause problems in a cell.

Normally, electrons like to have a balanced number of electrons; free radicals try to fill their missing "slot" by stealing an electron from a nearby molecule. This starts a chain reaction, as the deprived molecules try to grab electrons from their neighbors, who in turn try to grab electrons from their neighbors. This process is called oxidation, and is chemically the same process whereby oxygen rusts iron and turns peeled apples brown.

In the body, free radicals can attach to molecules of fat in nerve cell membranes, and thus upset the delicate functions performed by membranes - such as regulating the amount of calcium that goes in and out of the cell. Free radicals have been implicated in the tissue damage in strokes. They are also implicated in the spread of cancer and in the effects of aging (e.g. wrinkles and cell death). Nerve cells producing the mutated form of amyloid protein - the kind that forms amyloid plaques in Alzheimer's disease - seem to produce more free radicals.

Anti-oxidants are substances which are helpful in defending against the effects of free radicals, either by breaking the free radicals into harmless substances, or by binding to them and preventing them from attacking healthy cells.