Alpha-band characteristics in EEG spectrum indicate reliability of frontal brain asymmetry measures in diagnosis of depression.

Asymmetry in brain activity has been hypothesised to be a potential marker for depression. However, it is not yet fully understood nor is it reliable enough to be in regular clinical use. In this study frontal Electroencephalograph (EEG) recordings were taken from 21 subjects, from which Frontal Brain Asymmetry (FBA) ratios were calculated. The results were classified according to whether or not the subject had a recent history of depression, and by the presence or absence of a characteristic peak in the `alpha' region of the EEG spectrum. It was found that subjects with current or previous incidence of depressive disorders tend to have an FBA ratio that lies towards the extremities of the distribution, and that the presence of a `clear alpha peak' made the assessment process more reliable.