Serotonin and Neuron-specific Enolase: Serum Acute and Mid-term Levels and their Association With Posttraumatic Depression

Objectives: To investigate the association between serotonin (SER), cholesterol, and neuron-specific enolase (NSE) serum levels with depression after traumatic brain injury (TBI). Materials and Methods: Seventy-four patients with the diagnosis of TBI were included in our study. Admission computed tomography scans of all patients were analyzed. Serum concentrations of SER, NSE, low-density lipoprotein, and cholesterol were measured within on admission. Serum levels of SER and NSE were also measured at discharge and at the 6-month follow-up evaluation. In addition, serum NSE and SER levels were measured in a control group of 44 healthy volunteers. The TBI patients in our cohort were divided into 3 groups according to their admitting Glasgow Coma Scale and their discharging Glasgow Outcome Scale scores. Likewise, depressive symptoms were characterized using the Diagnostic and Statistical Manual of Mental Disorders criteria and the Mini-International Neuropsychiatric Interview. Results: The measured SER serum levels were significantly lower (P < 0.01) in TBI patients compared with the normal controls. Analysis of our data showed no correlation between the levels of SER, NSE, cholesterol, and low-density lipoprotein. The NSE serum levels were found to be elevated in our TBI group. However, these levels were not different between patients with depressive symptomatology. SER and cholesterol serum levels were lower in TBI patients developing depressive symptoms compared with those with no depression in a statistically significant manner. Fifty-seven percent of our patients developed depressive symptomatology. Conclusions: Decreased serum SER concentration may serve as an additional biochemical risk marker of posttraumatic mental disturbances