Table 3. Results of correlation analysis between clinical variables and GMV in MDD group.

Areas	HDRS scores	Illness duration
nMDD
Right dorsolateral prefrontal cortex	r = 0.231, p = 0.238	r = 0.025, p = 0.901
Left middle frontal gyrus	r = −0.108, p = 0.585	r = 0.208, p = 0.289
Left thalamus	r = 0.327, p = 0.089	r = −0.298, p = 0.123
Right insula	r = 0.258, p = 0.185	r = −0.222, p = 0.256
tMDD
Left middle frontal gyrus	r = 0.093, p = 0.637	r = 0.051, p = 0.798
Right orbitofrontal cortex	r = 0.291, p = 0.132	r = −0.030, p = 0.880

GMV: gray matter volume.

HDRS: Hamilton Depression Rating Scale.

nMDD: medication-naïve major depressive disorder.

tMDD: treated major depressive disorder.