In a 12-year study of 200 volunteers, U.S. researchers found that those with the lowest levels of leptin, the hormone that controls appetite, were more likely to develop Alzheimer’s disease. The study continues on work that links low leptin levels to brain plaques, which are found in Alzheimer’s patients, and means leptin might be of use both as a marker of the disease one day, and a treatment. Leptin, which is produced by fat cells, tells the brain when the body is full, reducing appetite. It also seems to benefit brain function. Working in mice, researchers found those who received leptin were better able to find their way through a maze. In the latest research from Boston University Medical Center, regular brain scans were performed on elderly volunteers. One quarter of those with lowest leptin levels went on to develop Alzheimer’s, compared to 6 per cent with the highest levels.