Researchers find replicable neuroimaging features for MDD
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Major depressive disorder exhibits spatially convergent structural and functional brain abnormalities, suggesting replicable neuroimaging features associated with the disorder, according to results of a meta-analysis published in American Journal of Psychiatry. This association goes beyond the transdiagnostic effects reported in previous meta-analyses and supports research focused on brain regions linked to depression, researchers noted.
“We were able to identify select brain areas in major depression that are impacted by both structural (experience gray matter atrophy) and functional (blood flow, neural activation, metabolism) disruption,” Jodie P. Gray, MS, of the Research Imaging Institute at The University of Texas Health Science Center at San Antonio, told Healio Psychiatry. “Our findings also replicate long-standing hypotheses for select brain regions that are impacted by MDD, namely the subgenual cingulate cortex.”
MDD imaging studies have shown functional and structural abnormalities in various spatially diverse brain regions; however, quantitative meta-analyses have not identified statistically significant between-study spatial convergence, aside from transdiagnostic-only effects. To test the hypothesis that major depression exhibits spatially convergent functional and structural brain abnormalities, Gray and colleagues conducted a coordinate-based meta-analysis. They noted that this method “offers a large-scale data-driven approach to the identification of brain regions consistently altered by disease by testing for spatial convergence across reported findings from previously published neuroimaging studies.”
The analysis included voxel-based morphometry studies and resting -state voxel-based pathophysiology studies of blood flow, regional homogeneity, glucose metabolism and amplitude of low-frequency fluctuations (ALFF) and fractional ALFF. The researchers grouped input data into three primary meta-analytic classes — decreased function, increase function and gray matter atrophy in patients with major depression compared with healthy controls. They grouped data across primary categories in secondary analyses and by absence of psychiatric comorbidity and medication status in tertiary analyses. For all analyses, they used activation likelihood estimation.
Gray and colleagues identified 92 publications reporting 152 experiments, which included 2,928 patients with MDD. The primary analyses did not detect convergence across studies, but the secondary analyses identified portions of the amygdala, putamen, hippocampus and subgenual cingulate cortex as demonstrating convergent abnormalities. Relative to the secondary analyses, the tertiary analyses showed improved convergence.
“These findings suggest that clinical heterogeneity reflects neurobiological heterogeneity, in that significant findings emerged only for the most clinically homogenous subgroups,” Peter T. Fox, MD, director of the Research Imaging Institute at the University of Texas Health Science Center, told Healio Psychiatry. “Ideally, this study will provide a framework for constructing network models that can serve as neuroimaging biomarkers of MDD.” – by Joe Gramigna
Disclosures: Fox reports research support from the Cancer Prevention and Research Institute of Texas, NIH, the Mathers Foundation, the U.S. Department of Defense and the U.S. Department of Veterans Affairs. Gray reports research-training support from a grant through the U.S. Department of Defense and honoraria from Mind Science Foundation. Please see the study for all other authors’ relevant financial disclosures.