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Quantitative MRI of the hippocampus and amygdala in severe depression
E Mervaala1, J Föhr, M Könönen
1Department of Clinical Neurophysiology, University Hospital of Kuopio, Finland.
Background:
There is little evidence to support possible structural changes in the amygdala and hippocampus of patients with severe depression.
Methods:
Quantitative MRI of the amygdala and hippocampus, as well as proton spectroscopy (MRS) of mesial temporal structures were studied in 34 drug-resistant in-patients with major depression and compared with 17 age-matched controls. Volumetric MRI data were normalized for brain size.
Results:
The volume of the left hippocampus was significantly smaller in the patients compared with the controls. Both groups exhibited similar significant hippocampal asymmetry (left smaller than right). The patients, but not the controls, had significant asymmetry of the amygdalar volumes (right smaller than left). No differences were observed between the patients and controls in the T2 relaxation times for the hippocampus and amygdala. Mesial temporal lobe MRS revealed a significantly elevated choline/creatine ratio in the patients compared with the controls.
Conclusions:
This quantitative MRI study provides support for a possible association between structural and biochemical substrates and severe drug-resistant major depression.
Insights
Structural brain changes, including a smaller left hippocampus and amygdalar asymmetry, are linked to severe depression. This magnetic resonance imaging (MRI) study suggests biochemical alterations in the brain
Area of Science:
- Neuroimaging
- Psychiatry
- Neuroscience
Background:
- Limited evidence exists regarding structural brain changes in severe depression.
- Investigating the amygdala and hippocampus in major depressive disorder is crucial.
Purpose of the Study:
- To investigate structural and biochemical differences in the amygdala and hippocampus in patients with severe, drug-resistant major depression.
- To compare these findings with age-matched healthy controls.
Main Methods:
- Quantitative magnetic resonance imaging (MRI) was used to measure amygdala and hippocampus volumes.
- Proton spectroscopy (MRS) assessed mesial temporal structures.
- 34 drug-resistant major depression patients were compared with 17 controls.
Main Results:
- Patients exhibited a smaller left hippocampus volume compared to controls.
- Significant amygdalar asymmetry (right smaller than left) was found in patients, but not controls.
- An elevated choline/creatine ratio in the mesial temporal lobe was observed in patients.
Conclusions:
- This study provides evidence for structural and biochemical alterations in severe, drug-resistant major depression.
- Findings suggest a link between brain structure/biochemistry and the pathophysiology of depression.