Gene change linked to poor memory - Memory - brain-derived neurotrophic factor chemical - Brief Article

Science News, Nov 23, 2002

A subtle change in a gene encoding a brain chemical may give some people better memory skills than others.

Known as brain-derived neurotrophic factor (BDNF), the chemical has become a hot topic among neuroscientists. BDNF is known to promote the development of the nervous system in early life, as well as help nerve cells survive when exposed to stresses. More recently, scientists have suggested it has a role in tuning the way nerve cells talk to each other and, thus, a role in memory.

Ahmad R. Hariri of the National Institute of Mental Health in Bethesda, Md., and his colleagues have been comparing people who have different combinations of two variants of the BDNF gene. One variant incorporates the amino acid valine at a certain spot within BDNF, while the other variant incorporates methionine there. According to Hariri, the "val" version of BDNF moves about normally inside nerve cells of the hippocampus, a brain region involved in memory. The "met" version, however, doesn't travel to BDNF's normal target locations within the hippocampal nerve cells.

People inheriting two copies of the val-BDNF variant from their parents seem to do better on certain visual-memory tasks than do people with two met-BDNF variants or one of each, says Hariri.

Furthermore, in a brain-scan study involving a visual-memory task that typically triggers nerve-cell activity in the hippocampus, the researchers found that people with two val-BDNF gene variants had more activity in that brain region than did those with one or two met-BDNF variants.--J.T.