Low Serotonin Tied to Stress

North Carolina researchers report that individuals with low levels of the serotonin indicator 5-hydroxyindoleacetic acid (5-HIAA) show a significant stress-induced increase in proinflammatory cytokines that have been associated with atherosclerosis.

"This suggests that long-term stress, depression, or hostility, which are predictive of low levels of serotonin, may also be risk factors for atherosclerosis," Dr. Edward C. Suarez of Duke University Medical Center told Reuters Health in an interview during the annual meeting of the American Psychosomatic Society annual meeting in Savannah, Georgia, where he presented his findings.

Dr. Suarez and colleagues measured 5-HIAA levels in the cerebrospinal fluid of 56 healthy adults aged 18 to 49 years to determine serotonin levels.

The following day, study participants spent 1-1/2 hours recalling events that caused them anger or sadness. The researchers obtained blood samples, both prior to and immediately following the stress protocol to measure levels of interleukin 1-alpha (IL-1a) and tumor necrosis factor-alpha (TNF-a).

"The 18 participants with low 5-HIAA showed 5- to 6-fold higher IL-1-alpha levels than those in the moderate to high 5-HIAA groups," Dr. Suarez told Reuters Health.

Dr. Suarez added that "men in the low 5-HIAA group had 2-fold higher levels of TNF-alpha compared with men with moderate to high concentrations of 5-HIAA." "In women the opposite occurred, possibly due to estrogen," he said.

The results of this study show that low serotonin levels, which are characteristic of behavioral risk factors of atherosclerosis, are associated with the same inflammatory responses that promote atherogenesis.

This means that "a person's external behavior may have a direct effect on the way immune cells work," Dr. Suarez said.

Page Last Updated:  06/29/2005