Hippocampal Volume Dynamics in Major Depressive Disorder

The hippocampus is a pivotal structure in mood regulation, memory and stress adaptation. In major depressive disorder (MDD), cumulative evidence indicates both global volume loss and discrete subfield alterations. Recurrent episodes, elevated glucocorticoids and impaired neurogenesis contribute to reductions in cornu ammonis (CA) regions and the dentate gyrus. Conversely, successful treatment and remission can stabilise or partially reverse structural deficits, reflecting underlying neuroplasticity. Dynamic changes in hippocampal volume have been linked to illness duration, symptom severity and specific clinical features such as anhedonia. Advanced imaging has revealed that regional variation—rather than uniform atrophy—better explains cognitive and affective dysfunction in MDD. Understanding these volume dynamics offers insight into pathophysiology, prognosis and the development of targeted interventions.

Research from Nature Portfolio

Longitudinal magnetic resonance imaging in treatment-resistant depression and healthy volunteers has examined ketamine’s rapid neuromodulatory effects on hippocampal and adjacent limbic structures. Scans at baseline, 1–2 days and 9–10 days post-infusion revealed minimal change in hippocampal subfield volumes but a modest increase in left amygdalar volume at the interim assessment in depressed individuals. These findings suggest that while ketamine exerts swift synaptic plasticity, volumetric shifts in the human hippocampus may be subtle or delayed, underscoring the importance of timing and subfield-specific analysis when evaluating fast-acting antidepressant mechanisms.

Hippocampal Volume Dynamics in Major Depressive Disorder publication trend

The graph below shows the total number of articles in hippocampal volume dynamics in major depressive disorder across all publications each year (not limited to Nature Index journals).

Technical terms

Hippocampus: A brain region essential for memory formation, emotion regulation and stress response.

Subfields (CA1, CA3): Functionally distinct hippocampal compartments; CA1 is critical for output signalling, CA3 for pattern completion.

Dentate gyrus (DG): A hippocampal subregion where adult neurogenesis occurs and contributes to mood and memory processes.

Hippocampal fissure: A cerebrospinal fluid-filled cleft delineating hippocampal anatomy, often assessed for volumetric variation.

Hippocampal-amygdaloid transition area (HATA): A transitional zone between the hippocampus and amygdala implicated in affective processing.

Treatment-resistant depression (TRD): MDD unresponsive to at least two standard antidepressant trials, often requiring rapid-acting therapies.

FreeSurfer: Automated software for cortical and subcortical volumetric segmentation in MRI analysis.

References

1. Association of hippocampal subfield volumes with prevalence, course and incidence of depressive symptoms: The Maastricht Study. The British Journal of Psychiatry (2023).
2. Hippocampal volume changes after (R,S)-ketamine administration in patients with major depressive disorder and healthy volunteers. Scientific Reports (2024).
3. Altered hippocampal subfield volumes in major depressive disorder with and without anhedonia. BMC Psychiatry (2023).
4. Structural changes in the hippocampus in major depressive disorder: contributions of disease and treatment. Journal of Psychiatry and Neuroscience (2010).