Turmeric: hope in Alzheimer’s disease?

A member of the ginger family, turmeric (Curcuma longa) is a perennial plant cultivated throughout tropical Asia, and is a widely used ingredient in Asian cuisine. The bulb and rhizomes are boiled and dried, resulting in the familiar bright yellow powder.

Turmeric has been used in Chinese and Indian medicine for hundreds of years to treat a range of problems, including arthritic pain, menstrual problems, flatulence and toothache.

The major yellow pigment is curcumin (diferuloylmethane), a phenolic antioxidant. Most natural antioxidants contain either beta-diketone or polyphenolic functional groups, but curcumin possesses both of these moieties, resulting in a greater effect.

In more recent years, research has been carried out on in vitro studies of curcumin as an anticancer agent, particularly against cancers affecting the gastrointestinal tract. The mechanism may be associated with the ability of curcumin and its analogues to induce apoptosis (programmed cell death) in cancer cells. Other studies have indicated that curcumin may also have a radiosensitising effect on cancer cell cultures.

There has also been great interest in reports on the possible use of curcumin as an agent in the treatment of Alzheimer’s disease. Scientists have for many years noticed that the Indian subcontinent has one of the lowest incidences of Alzheimer’s in the world. The disease affects just 1 per cent of the population, compared with a figure nearer to 10 per cent in the US and the UK.

In vitro research has concentrated on two areas of curcumin activity. An Italian study suggested that curcumin may stimulate production of the antioxidant bilirubin, which protects the brain against the oxidative injury thought to be a major factor in the progression of Alzheimer’s disease.

In another study in North Carolina, it was suggested that curcumin may prevent the spread of amyloid plaques among nerve fibres in the brain, another cause of disease progression.

There is strong evidence that curcumin binds to the plaques, and studies involving rats eating a curcumin-rich diet have demonstrated that the existing plaques are dissolved and new ones prevented from forming.

These studies have received mixed receptions from experts, but the Alzheimer’s Research Trust has expressed interest, and is looking forward to the trials being extended to human studies.