Metabolite of Interest | Key Properties | Findings for Patients with Depression Relative to Controls |
---|---|---|
Glu/Glutamine | Complex signal Requires difference technique at intermediate field strengths | Decreased Glu/Gln in anterior cingulate19,56,57 Decreased Glu/Gln in amygdala-hippocampus58 Decreased Glu/Gln in prefrontal cortex62 Elevated Glu in occipital cortex59 Reduction of Glx (mainly Glu and Gln) in depressive disorder but elevation in bipolar disorder60 Response to treatment: increased levels with ECT19 |
GABA | Complex signal Requires different technique at intermediate field strengths | Decreased in occipital cortex59,61 Decreased in occipital and anterior cingulate cortex63 Decreased in prefrontal cortex62 Response to treatment: patients who were most severely depressed and who had lowest GABA concentrations showed largest increase after SSRI treatment59 |
NAA or NAA/Cr | Only present in neurons Change reflects loss or decreased function of neurons | Decreased NAA/Cr in thalamus64 Decreased NAA in caudate65 Meta-analysis: no significant differences in NAA between depressed and healthy subjects in basal ganglia and frontal lobe structures50 |
Cr+PCr | Reflects tissue energetics ∼7.8 μmol/g117 | No significant differences in Cr levels in frontal lobe structures between depressed and healthy subjects50 |
Cho | Concentration of pool: ∼2 μmol/g117 Reflects mobile Cho (TMA) moieties Cho concentration rate limiting step in acetylcholine synthesis Dynamic equilibrium with acetylcholine and phospholipid pathways | Mixed findings Meta-analysis: elevated in basal ganglia50 Response to treatment: choline elevation reverses with antidepressant treatment50 |
mIns | Diverse role in central nervous system (gliosis, cytoskeleton, cellular signaling) | Generally negative findings in anterior cingulate cortex, basal ganglia Mixed results for prefrontal cortex54 |
Note:—ECT indicates electroconvulsive therapy; SSRI, selective serotonin reuptake inhibitor; TMA, trimethylamine.