Comparison of Frontal Alpha Asymmetry Among Schizophrenia Patients, Major Depressive Disorder, and Healthy Controls
Abstract Background Electroencephalography (EEG) frontal alpha asymmetry (FAA) has been observed in several psychiatric disorders. However, dominance in left or right frontal alpha activity remains inconsistent in patients with major depressive disorder (MDD), patients with schizophrenia, and healthy controls. This study compared FAA among patients with MDD, schizophrenia, and healthy control. Methods We recruited 20 patients with MDD, 18 patients with schizophrenia, and 16 healthy individuals. The EEG alpha frequency ranged from 8.0 to 12.0 Hz. FAA was expressed as the difference between absolute power values in both the right and left electrodes in the alpha frequency range (common-log-transformed F4–F3 and F8–F7). Hamilton depression and anxiety rating scales were evaluated in patients with MDD. Positive and negative syndrome scales were evaluated in patients with schizophrenia. Results Patients with schizophrenia showed significantly lower left frontal lobe activity than healthy controls (FAA, schizophrenia vs. healthy: -0.10 ± 0.05 vs. -0.05 ± 0.05). There were no significant differences in FAA between patients with schizophrenia and MDD as well as between patients with MDD and healthy controls. Conclusions The present study suggests that frontal alpha asymmetry indicates a breaking neural activity in schizophrenia. Breaking rhythmic activity as a left-lateralized FAA can be a neuropathological attribute in patients with schizophrenia but lack of sample size and information such as medication and duration of illness, all of which could make it difficult generalize finding.