31P RINEPT MRSI and VBM reveal alterations in brain aging associated with major depression

Abstract

Purpose: Phosphomono- and diesters, the major components of the choline peak in (1) H magnetic resonance spectroscopy, are associated with membrane anabolic and catabolic mechanisms. With the refocused insensitive nuclei-enhanced polarization transfer technique, these phospholipids are edited and enhanced in the (31) P MR spectrum. In depressed patients, alterations of the choline peak and cerebral volume have been found, indicating a possible relation. Thus, combining MR phosphorous spectroscopy and volumetry in depressed patients seems to be a promising approach to detect underlying pathomechanisms.

Methods: Depressed in-patients were either treated with antidepressive medication or with electroconvulsive therapy and compared to matched healthy controls. (31) P magnetic resonance spectroscopy imaging was conducted before and after the treatment phases. A 3D MRI dataset for volumetry was acquired in a dedicated (1) H head coil.

Results: Phosphocholine and phosphoethanolamine were increased in depressed patients. Though patients responded to the treatments, phospholipids were not significantly altered. An increased age-related gray matter loss in fronto-limbic regions along with an altered relation of phosphomonoesters/phosphodiesters with age were found in depressed patients.

Discussion: The findings of increased phosphomonoesthers and an age*group interaction for gray matter volumes need further research to define the role of phospholipids in major depression and possible associations to gray matter loss.

Keywords: electroconvulsive therapy; hippocampus; major depression; phosphorous magnetic resonance spectroscopy; refocused insensitive nuclei-enhanced polarization transfer; voxel based morphometry.