Genotype-stratified Default Mode Network hyperconnectivity in major depressive disorder: an MR imaging genetics study

Area of Science:

• Neuroscience
• Psychiatry
• Genetics

Background:

• Major depressive disorder (MDD) is a complex psychiatric condition with significant genetic and neurobiological factors.
• Understanding the genetic underpinnings of MDD is crucial for developing effective treatments.

Purpose of the Study:

• To investigate genetic variants associated with MDD.
• To examine the impact of these variants on neurotransmitter pathways and brain connectivity.
• To explore the relationship between genetic variations, brain network function, and clinical symptoms in MDD.

Main Methods:

• Whole-exome sequencing (WES) and Sanger sequencing were used to identify genetic variants in 69 MDD patients.
• Resting-state functional MRI (rs-fMRI) was employed to assess functional connectivity, particularly within the Default Mode Network (DMN).
• Genotype-connectivity associations were analyzed, correlating DMN connectivity with Hamilton Depression Rating Scale (HAM-D) scores and depressive episode incidence.

Main Results:

• WES identified variants in 21 genes related to neurotransmission and synaptic plasticity.
• Specific variants in TPH1 (rs1799913) and DAOA (rs2391191) were associated with significantly increased DMN connectivity.
• Heightened DMN synchrony positively correlated with HAM-D scores and the occurrence of depressive episodes.

Conclusions:

• Variations in TPH1 and DAOA genes are linked to atypical DMN connectivity in MDD.
• These findings highlight the role of serotonergic and glutamatergic pathways in maladaptive neural coupling.
• Genotype-stratified DMN metrics may serve as intermediate neural phenotypes for MDD, warranting further longitudinal research.