Brain Chemical May Drive Obesity

(August 29, 2008) - A brain chemical that plays a role in long term memory also appears to be involved in regulating how much people eat and their likelihood of becoming obese. (Read about "Obesity") That's the conclusion of a National Institutes of Health study of a rare genetic condition.

Brain derived neurotrophic factor (BDNF) is, as its name implies, produced in the brain. Studies of laboratory animals have suggested it also helps control appetite and weight. The NIH study, appearing in the New England Journal of Medicine, provides the first strong evidence that BDNF is important for body weight in human beings as well.

The NIH researchers studied children and adults with WAGR syndrome, a rare genetic condition. The researchers found that some of the people with this syndrome lack a gene for BDNF and have correspondingly low blood levels of the substance. The people in this subgroup also have unusually large appetites and a strong tendency towards obesity.

"This is a promising new lead in the search for biological pathways that contribute to obesity," said Duane Alexander, M.D., director of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development. "This finding may eventually lead to the development of new drugs to regulate appetite in people who have not had success with other treatments."

WAGR syndrome is an acronym for the complex of symptoms seen in people who have the condition. These include Wilms tumor, a tumor of the kidneys (Read about "Kidney Cancer"); aniridia, absence of the iris, in the eye; genital and urinary tract abnormalities (Read about "Genitourinary Birth Defects"); and mental retardation. WAGR syndrome occurs in one out of every 500,000 to 1 million persons.