Distinguishing quantitative EEG findings between adjustment disorder and major depressive disorder

Abstract

Purpose: Adjustment disorder (ADJ) is a common diagnosis. However, it is difficult to distinguish ADJ from other major Axis I disorders, such as major depressive disorder (MDD). The aim of this study was to determine the distinguishing neurophysiological characteristics between ADJ and MDD using quantitative analysis of electroencephalogram (QEEG). Methods: The subjects included 30 patients with ADJ and 51 patients with MDD. QEEG absolute power and coherence were calculated for the delta, theta, alpha and beta bandwidths, assessed at 8 pairs of electrodes in both hemispheres during a resting, eyesclosed condition. Results: The mean ages of the ADJ group and the MDD group were 38.4±11.8 years and 37.33±10.41 years, respectively. In the ADJ group, health problems (53.3%) were the most common type of predisposing stressor, followed by familial conflict (16.7%), military problems (13.3%), interpersonal problems (10%) and occupational problems (6.7%), in order. Comparing the mean absolute power value for every frequency band, there were significant differences in the alpha and high-beta bands between the ADJ and MDD groups, respectively, particularly in the right and left frontocentral areas. The absolute alpha power was found to be lower in the ADJ group than in the MDD group at Fp1 (p = 0.036), Fp2 (p = 0.031), F3 (p = 0.025), F4 (p = 0.037), F7 (p = 0.042), F8 (p = 0.023), C3 (p = 0.039) and C4 (p = 0.034). The absolute highbeta power was also found to be lower in the ADJ group than in the MDD group, particularly at both the right and left frontocentral areas: at Fp1 (p = 0.035), Fp2 (p = 0.022), F3 (p = 0.029), F4 (p = 0.016), F7 (p = 0.022), F8 (p = 0.024), C3 (p = 0.019) and C4 (p = 0.028). In temporoparieatal areas, patients with ADJ showed higher alpha power at T3 (p = 0.049), and higher high beta power at T5 (p = 0.021), P3 (p = 0.028) and P4 (p = 0.071) compared to patients with MDD. The values for intrahemispheric coherence were higher in the MDD group than in the ADJ group for the 2 pairs of electrodes on the right side. The significant differences in intrahemispheric coherence value were pronounced between P4O2 for the delta band (p = 0.043) and the beta band (p = 0.009). Interhemispheric coherence values were higher in the MDD group than in the ADJ group that between F3F4 (p = 0.036) and T3T4 (p = 0.041) for the alpha band. Conclusions: The differences in QEEG power and coherence in our investigation suggest that underlying pathophysiologic mechanisms may be different between ADJ and MDD. QEEG might be considered a useful adjunct to clinical differentiation between ADJ and MDD.