Being Overweight Reduces Health of Hippocampus

A new study finds that being overweight relates to reduced levels of a molecule that reflects the health of the hippocampus, a part of the brain involved in memory, learning, emotions and likely appetite control.

Jeremy D. Coplan, professor of psychiatry at SUNY Downstate, led the multicenter team that visualized the molecule, N-acetyl-aspartate (NAA), using magnetic resonance spectroscopy, a non-invasive magnetic resonance imaging (MRI) application. NAA is generally associated with the health of brain cells.

"Overweight study participants exhibited lower levels of NAA in the hippocampus than normal weight subjects. The effect was independent of age, sex, and psychiatric diagnoses," reads the press release announcing the findings, which were published in Neuroimage: Clinical.

The hippocampus, a seahorse-shaped organ within the brain, which is generally understood to formulate and preserve memories, does not have a well established connection to appetite control, Coplan noted.

"The relevance of the finding is that being overweight is associated with specific changes in a part of the brain that is crucial to memory formation and emotions, and probably to appetite," Coplan said. This research is thought to be the first human study documenting a relationship between NAA levels and body weight.

"Whether low NAA is a consequence of being overweight, causes being overweight, or a combination of both remains to be determined," Coplan added. "Future studies are planned to focus on whether weight loss leads to an increase in NAA."

"We also found that high worry also produced low levels of NAA in the hippocampus, but was not associated with a high body mass index (BMI)," Coplan said. The researchers studied individuals with a BMI equal to or greater than 25. Normal weight is defined as a BMI of 18.5-24.9, overweight between 25 and 29.9, and obesity at 30 or greater.