The Role of Electroencephalography in the Differential Diagnosis of Unipolar and Bipolar Depression

The importance of the timely detection and differential diagnosis of depressive disorder and bipolar affective disorder (BAD) is beyond doubt. In cases with difficult differential diagnoses, clinicians can call on objective investigation methods such as electroencephalography. This review summarizes and systematizes current methods for the differential diagnosis of unipolar and bipolar depression based on electroencephalography data. A literature search was conducted using the search terms depression, bipolar disorder, unipolar depression, differential diagnosis, neuromarkers, electroencephalography, and quantitative EEG. This search was run in the PubMed, NCBI, ResearchGate, RSCI, Scopus, and Google Scholar databases from 2000 to 2022. Resting EEG parameters in patients are generally ambiguous and require further clarification; however, data have been obtained showing differences in the asymmetry of bioelectrical activity, spectral power, and coherence between patients with bipolar disorder and unipolar depression. A number of studies of evoked potentials (EP) have yielded similar results – longer P300 latency and decreases in its amplitude in patients with bipolar disorder as compared with those with unipolar depression, indicating that the EP method has promise in solving the problem of differential diagnosis. © 2023, Springer Nature Switzerland AG.