To explore the discrepancies of individualized frequency and band power between major depressive disorder (MDD) and controls in resting state, and the association of abnormal spectral power with clinical severity of MDD.

Whole-head MEG recordings were collected in 19 patients with MDD and 19 non-depressed controls in eye-closed resting state. Individual spectral power of each subject was calculated based on the method of individually defined spectral bands and widths.Spearman correlation coefficient was used to examine the relation between the significant abnormal band power and the clinical indices of depression severity according to HAMD₁₇ scores.

The power of various frequency bands of patients was decreased as follows: the lower alpha2 ［(0.27±0.19) fT²vs.(0.51±0.37) fT²; t=-2.224, P=0.016］and upper alpha band ［(0.42±0.39) fT²vs. (1.28±0.62) fT²; t=-1.856, P=0.036］ in the right frontal lobe, and the theta band in the right temporal lobe［(1.13±0.42) fT²vs. (1.48±0.83) fT²; t=-1.785, P=0.041］. The power was increased as follows: the beta frequency in the left parietal ［(4.35±2.64) fT²vs. (2.82±1.29) fT²; t=2.590, P=0.007］, right parietal ［(4.45±2.48) fT²vs. (2.91±1.99) fT²; t=2.670, P=0.006］and left occipital lobe［(2.03±1.06) fT²vs. (1.02±0.84) fT²; t=1.835, P=0.037］, and the lower alpha1 band in the right occipital lobe ［(6.49±2.43) fT²vs. (5.22±2.78) fT²; t=1.769, P=0.043］.A positive correlation was observed between the right occipital lower alpha1 power and HAMD₁₇ scores for depression (r=0.508, P=0.026).

MDD patients may have a broad disorganization of spectral power which be characterized with complex alpha activity patterns.The power of lower alpha1 of the right occipital lobe may be a potential indicator of depression severity.

Depressive disorder; Magnetoencephalography; Spectral analysis; Resting state; Individual alpha frequency