Mapping The Depressed Brain: A Systematic Review and Activation likelihood Estimation Meta-analysis of fMRI studies

Abstract

Background: Major Depressive Disorder (MDD) is a major cause of disability for individuals. This disorder is self-diagnosed by reports and interviews. Studies of functional magnetic resonance imaging (fMRI) have found that these disorders affect brain functions. Further research, such as meta- analysis, is needed to arrive at reliable neural biomarkers and more accurate results. Hypothesis: the null hypothesis tested in this study was that there are no consistently reported abnormal brain regions in the depression neuroimaging literature. Aims: this study aims to Identify consistent functional brain abnormalities in depression by applying a systemic review and meta-analysis of fMRI using Activation likelihood Estimation (ALE). Methods: A systematic review and ALE meta-analysis were performed on 28 fMRI studies from 2000 to 2024. Studies with MNI or Talairach coordinates were analysed using GingerALE to identify consistent brain activation pattern in MDD. Results: The ALE meta-analysis revealed consistent abnormalities in Major Depressive Disorder (MDD), characterised by amygdala hyperactivation and dorsolateral prefrontal cortex (dlPFC) hypoactivation, associated with emotional reactivity and cognitive control. Supplementary clusters in the insula, hippocampus, and basal ganglia indicate disturbances in interoception, memory, and reward processing. Conclusion: MDD is associated with persistent brain abnormalities, such as amygdala hyperactivation and dlPFC hypoactivation, as well as disturbances in the insula, hippocampus, and basal ganglia. These findings confirm a common neuronal signature of depression and provide targets for enhanced diagnosis and treatment.