Molecular imaging findings for treatment resistant depression

Area of Science:

• Neuroscience
• Radiology
• Psychiatry

Background:

• Major depressive disorder (MDD) affects many, with 40% developing treatment-resistant depression (TRD).
• TRD presents a significant global health burden due to limited response to conventional treatments.
• Molecular imaging offers in vivo insights into brain function and disease mechanisms.

Purpose of the Study:

• To review and summarize positron emission tomography (PET) and single photon emission tomography (SPECT) studies on TRD.
• To examine the neurobiology and treatment-induced changes in TRD using molecular imaging.
• To identify potential imaging biomarkers for TRD pathophysiology and treatment response.

Main Methods:

• Systematic review and summary of 51 published PET and SPECT studies.
• Inclusion of supplementary data from MDD and healthy control (HC) studies.
• Analysis of regional brain activity, neurotransmitter markers, and imaging indices related to treatment outcomes.

Main Results:

• Altered regional blood flow and metabolic activity were observed in key brain regions (e.g., anterior cingulate cortex, prefrontal cortex, insula, hippocampus, amygdala, striatum).
• Limited data showed changes in serotonin, dopamine, amyloid, and microglia markers in TRD.
• Abnormal imaging findings correlated with treatment outcomes, suggesting clinical relevance.

Conclusions:

• PET and SPECT imaging reveal distinct neurobiological alterations in TRD.
• Specific brain regions and molecular markers show promise as imaging biomarkers for TRD.
• Future research should employ longitudinal, multimodal approaches with targeted radioligands for comprehensive TRD evaluation.