Personalized Medicine: Review and Perspectives of Promising Baseline EEG Biomarkers in Major Depressive Disorder and Attention Deficit Hyperactivity Disorder

Abstract

Personalized medicine in psychiatry is in need of biomarkers that resemble central nervous system function at the level of neuronal activity. Electroencephalography (EEG) during sleep or resting-state conditions and event-related potentials (ERPs) have not only been used to discriminate patients from healthy subjects, but also for the prediction of treatment outcome in various psychiatric diseases, yielding information about tailored therapy approaches for an individual. This review focuses on baseline EEG markers for two psychiatric conditions, namely major depressive disorder and attention deficit hyperactivity disorder. It covers potential biomarkers from EEG sleep research and vigilance regulation, paroxysmal EEG patterns and epileptiform discharges, quantitative EEG features within the EEG main frequency bands, connectivity markers and ERP components that might help to identify favourable treatment outcome. Further, the various markers are discussed in the context of their potential clinical value and as research domain criteria, before giving an outline for future studies that are needed to pave the way to an electrophysiological biomarker-based personalized medicine.

Brain arousal regulation as response predictor for antidepressant therapy in major depression

“…In line with that, other research groups found no differences in absolute or relative theta power38 or a decreased theta power in responders to antidepressants3940. Owing to the fact that another study found decreased theta activity to be associated with non-response41, the heterogeneity in results was recently explained with the origins of the measured theta activities14: the reduced widespread frontal activity within the responders3839 was ‘considered most likely’ as a sign of reduced drowsiness which may not be the case in the study investigating frontal midline theta activity41. For theta activity specifically assessed within the anterior cingulate cortex, results are again contradictory with both decreased and increased activity to be favourable for treatment outcome111213.…”

“…Different electroencephalographic (EEG) measures have been introduced as potential biomarkers for antidepressant treatment response, such as frequency band power, alpha hemispheric asymmetry, antidepressant treatment response (ATR) index, theta cordance and event-related potentials111213141516. More recently, the assessment of arousal regulation has become a scope of research on antidepressant treatment response171819 and has been defined as a basic and trans-diagnostically relevant neurobiological dimension within the Research Domain Criteria project (RDoC)20.…”

“…Such arousal levels cannot only be differentiated during sleep (then labelled as sleep stages) but also during wakefulness (then called EEG-vigilance stages). Already small differences or changes in the level of brain arousal will have profound effects on the temporo-spatial pattern of EEG activity upon which most of the previous measures are based111213141516. Recently the pathogenic relevance of brain arousal regulation for affective disorders has been highlighted21.…”

Comparison of Electroencephalography (EEG) Coherence between Major Depressive Disorder (MDD) without Comorbidity and MDD Comorbid with Internet Gaming Disorder

“…So far, the results from several studies on coherence analysis in MDD remain controversial (1027), and no study has been conducted on coherence analysis in IGD. In the present study, inter-hemispheric coherence value for the alpha band between right and left frontal regions was significantly lower in the MDD+IGD group than the MDD-only group.…”

Pharmaco-EEG, Pharmaco-Sleep and EEG-Based Personalized Medicine

“…Stratifying patients based on such biomarkers can potentially reduce the well-known heterogeneity in imaging studies in psychiatry and result in new insights. This burgeoning field is reviewed by Olbrich et al [13], with a focus on personalized medicine in depression and ADHD, including recent insights from the large multicentre international study to predict optimized treatment in depression (iSPOT-D), which includes 1,008 depressed patients randomized to three different antidepressants.…”