Normal glutamate but elevated myo-inositol in anterior cingulate cortex in recovered depressed patients.
BACKGROUND
MRS studies of acutely depressed patients reveal decreased levels of total glutamate and glutamine (Glx) in frontal cortex which may reflect abnormalities of glutamate-glutamine cycling through astrocytes. Frontal Glx levels appear to be normalised after recovery from depression, but it is not known if this composite measure masks ongoing differences in glutamate or glutamine alone.


METHODS
Medication-free, fully recovered patients with a history of DSM-IV recurrent major depressive disorder (n=14) and healthy controls (n=16) were scanned at 3T. Short echo time PRESS and PRESS-J spectra were acquired from a 12 cm(3) voxel of frontal cortex incorporating the anterior cingulate.


RESULTS
Levels of Glx and of glutamate alone did not differ between groups. However, myo-inositol concentrations were significantly higher in those with a history of depression than in controls.


CONCLUSIONS
Abnormal MRS measures were not demonstrated during episodes of depression for these participants, so any evidence of changes with recovery is indirect.


CONCLUSIONS
The normal glutamatergic measures combined with elevated levels of the astrocytic marker, myo-inositol, suggest that recovery from depression may be associated with changes in glial function in frontal cortex.
Taylor
Matthew J
MJ
Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom. matthew.taylor@psych.ox.ac.uk
Selvaraj
Sudhakar
S
Norbury
Ray
R
Jezzard
Peter
P
Cowen
Philip J
PJ