Hyperleptinemia in subjects with persistent partial posttraumatic stress disorder after a major earthquake

Leptin, a peptide hormone derived from adipose tissue, regulates food intake and controls weight. Serum leptin levels may be elevated in critically ill patients and in cases of physical stress. Our aim was to examine the relationship between postdisaster psychiatric symptoms and serum leptin levels.

We recruited 92 subjects who visited emergency medical stations immediately after the giant earthquake seized middle Taiwan on September 21, 1999. Of these cases, 43 met the criteria for subsyndromal acute stress disorder. Eighteen months later, we measured serum leptin levels and performed in-depth psychiatric assessments using the posttraumatic stress disorder subset in the Mini International Neuropsychiatric Instrument and the Brief Symptom Rating Scale short form.

After we adjusted for age, gender, and body mass index, serum leptin levels were significantly higher in the persistent subsyndromal group (N = 15; estimated marginal mean, 9.641; 95% confidence interval, 7.673-11.610) than in others (estimated marginal means, 4.775-6.368). A hyperaroused state predicted a higher adjusted leptin level. On the Brief Symptom Rating Scale, general severity index, paranoid tendency, anxiety symptoms, and depressive symptoms were positively correlated with adjusted leptin levels.

We found a direct relationship between stress-related psychopathologic symptoms and serum leptin levels. Subjects with persistent subsyndromal posttraumatic stress disorder and hyperarousal had significantly higher serum leptin levels. Therefore, leptin may be a valid neuroendocrinologic marker for the hypervigilant state of vulnerable people who have faced tremendous danger and uncertainty. Further studies are needed to examine the correlation between leptin levels and hypothalamic-pituitary-adrenal axis function, particularly the inverted diurnal serum leptin levels in hyperaroused subjects.