RESUMEN
OBJECTIVE: Stress and elevated levels of glucocorticoids in patients with major depressive disorder (MDD) have been hypothesized to be associated with damage to the hippocampus. However the relationship between depression and hippocampal structure is unconfirmed. We investigated whether the chemical changes will occurr in the hippocampus of patients with MDD by using 1H-magnetic resonance spectroscopy (MRS) and explored the clinical meanings of hippocampal metabolites. METHODS: Fourteen female, right-handed patients with major depressive disorder and 12 healthy controls (age, sex, education and their dextrality matched) were included. We measured variables of time course of illness, severity of illness, levels of NAA, Cho and Cr in both hippocampus using 1HMRS. In addition, we performed neuropsychological tests in depressed subjects. RESULTS: There were no significant difference in the NAA/Cr, Cho/Cr, Cho/NAA between depressed and control subjects. In depressed subjects, significant negative correlations were observed between hippocampal NAA/Cr and duration of illness, duration of unmedication, severity of illness, respectively. Right hippocampal NAA/Cr was correlated with RCFT scores. CONCLUSION: These findings indicate damage to the hippocampus may not be a common feature in all depressed patients. However the results suggest that the illness burden and past treatment may influence hippocampal neurons and neuronal network in patients with MDD. Also, chemical changes in hippocampus may be associated with severity of illness and memory function.