Neurochemistry of late-life major depression: a pilot two-dimensional MR spectroscopic study.

Purpose: To evaluate a two-dimensional localized chemical shift correlated spectroscopy (L-COSY) sequence in elderly patients with major depression.

Materials And Methods: A total of 33 healthy elderly subjects and 15 elderly patients with major depression were investigated. A voxel size of 3 x 3 x 3 cm3 was chosen in the dorsolateral prefrontal region with predominantly white matter, with the use of three slice-selective radiofrequency (RF) pulses (90 degrees , 180 degrees , and 90 degrees). A chemical shift-selective (CHESS) sequence was used prior to volume localization for the presaturation of water. The two-dimensional raw data matrix consisted of 1024 complex points along the detection period (t2), and 100 increments along the evolution period (t1), resulting in a total acquisition time of approximately 27 minutes per acquisition. The metabolite ratios were calculated using the two-dimensional peak volumes with respect to the diagonal peak volume of total creatine (Cr) at 3.0 ppm.

Results: In the 33 elderly subjects, the mean ratio of choline (Cho) to Cr was 10% higher in men compared to women (P < 0.05), consistent with earlier findings obtained by one-dimensional MRS. When the metabolite ratios were compared in a subsample of 16 elderly female controls and 12 depressed female patients, the depressed geriatric patients had higher levels of myoinositol (mI), phosphoethanolamine (PE), and glutamate/glutamine (Glx) than the controls, although the differences were not statistically significant.

Conclusion: Our pilot study shows the feasibility of performing two-dimensional L-COSY successfully in elderly subjects and patients with late-life mood disorders. These findings are consistent with and expand on our earlier findings in major depressive disorder (MDD) detected with one-dimensional MRS.