Dynamic brain activity and thyroid dysregulation in suicidal ideation of MDD

Suicidal ideation (SI) in major depressive disorder (MDD) is closely associated with thyroid dysfunction and abnormal brain activity, yet their interplay remains insufficiently understood. Compared to healthy controls, this study investigates the relationship between thyroid function and dynamic brain activity in MDD patients with (SI-MDD) and without SI (nSI-MDD).

210 MDD patients and 103 healthy controls underwent thyroid function assessment and fMRI scanning. We computed the dynamic amplitude of low-frequency fluctuations (dALFF), which reflects neural activity patterns, and used one-way ANCOVA with post-hoc tests to identify group-level differences.

Our findings show that SI-MDD patients had significantly higher TSH levels and lower T3 levels compared to nSI-MDD and healthy controls (p < 0.05). Additionally, SI-MDD patients displayed reduced dALFF in regions critical for emotional and cognitive control, including the right orbitofrontal inferior gyrus (R.Orb.IFG) and right anterior cingulate cortex (R.ACC). Notably, T3 levels were positively correlated with dALFF in the R.Orb.IFG (r = 0.318, p = 0.001), while TSH levels were negatively correlated with dALFF in the R.ACC (r = -0.316, p = 0.001).

Our findings offer insight into associations between thyroid dysfunction and brain activity in SI-MDD, suggesting that thyroid biomarkers may have a role in understanding and managing SI, although these results need to be confirmed with further research.