Mood correlates with blood serotonin, but not with glucose measures in patients with recurrent suicidal behavior

Depressive mood and impulsive-aggressive behavior are relevant to suicidal behavior and have been associated with decreased central serotonergic function. Impulsive behavior and aggression have also been related to abnormal glucose metabolism. To investigate these relationships further, blood serotonin (5-HT), blood glucose measures (glycated hemoglobin (HbA1C) and fructosamine) and self-reported depressive symptoms and anger were repeatedly measured, during a 1-year follow-up, in 106 patients who had recently attempted suicide for at least a second time. A major DSM-III-R Axis I diagnosis or use of antidepressants were reasons for exclusion. Intra-individual variations in blood 5-HT were inversely correlated with variations in depressive mood, self-depreciation, and anger, and positively with variations in fructosamine. Intra-individual variations of HbA1c or fructosamine were not correlated with mood. Mean blood 5-HT levels per patient were positively correlated with mean scores of depression and self-depreciation. The contrast between the intra-individual and the inter-individual correlations may reflect a difference between short- vs. long-term effects. The results do support an association between serotonergic function and mood, but not between glucose metabolism and mood, in recurrent suicide attempters.