Functional connectivity in major depression: increased phase synchronization between frontal cortical EEG-source estimates

Sebastian Olbrich, Anja Tränkner, Tobias Chittka, Ulrich Hegerl, Peter Schönknecht
Psychiatry Research Neuroimaging (Impact Factor: 3.36). 01/2014; DOI:10.1016/j.pscychresns.2014.02.010

ABSTRACT Structural and metabolic alterations in prefrontal brain areas, including the subgenual (SGPFC), medial (MPFC) and dorsolateral prefrontal cortex (DLPFC), have been shown in major depressive disorder (MDD). Still it remains largely unknown how brain connectivity within these regions is altered at the level of neuronal oscillations. Therefore, the goal was to analyze prefrontal electroencephalographic phase synchronization in MDD and its changes after antidepressant treatment. In 60 unmedicated patients and 60 healthy controls (HC), a 15-min resting electroencephalogram (EEG) was recorded in subjects at baseline and in a subgroup of patients after 2 weeks of antidepressant medication. EEG functional connectivity between the SGPFC and the MPFC/DLPFC was assessed with eLORETA (low resolution brain electromagnetic tomography) by means of lagged phase synchronization. At baseline, patients revealed increased prefrontal connectivity at the alpha frequency between the SGPFC and the left DLPFC/MPFC. After treatment, an increased connectivity between the SGPFC and the right DLPFC/MPFC at the beta frequency was found for MDD. A positive correlation was found for baseline beta connectivity and reduction in scores on the Hamilton Depression Rating Scale. MDD is characterized by increased EEG functional connectivity within frontal brain areas. These EEG markers of disturbed neuronal communication might have potential value as biomarkers.

Evaluation of neurofeedback in ADHD: The long and winding road

Biological Psychology 95 (2014) 1–3

Martijn Arnsa,b,∗, Hartmut Heinrichc,d, Ute Strehle

a Research Institute Brainclinics, Nijmegen, The Netherlands
b Utrecht University, Dept. Experimental Psychology, Utrecht, The Netherlands
c Dept. of Child and Adolescent Mental Health, University Hospital of Erlangen, Erlangen, Germany d Heckscher-Klinikum, d München, Germany
e University of Tuebingen, Tuebingen, Germany

abstract

Among the clinical applications of neurofeedback, most research has been conducted in ADHD. As an introduction a short overview of the general history of neurofeedback will be given, while the main part of the paper deals with a review of the current state of neurofeedback in ADHD. A meta-analysis on neurofeedback from 2009 found large effect sizes for inattention and impulsivity and medium effects sizes for hyperactivity. Since 2009 several new studies, including 4 placebo-controlled studies, have been published. These latest studies are reviewed and discussed in more detail. The review focuses on studies employing (1) semi-active, (2) active, and (3) placebo-control groups. The assessment of speci- ficity of neurofeedback treatment in ADHD is discussed and it is concluded that standard protocols such as theta/beta, SMR and slow cortical potentials neurofeedback are well investigated and have demon- strated specificity. The paper ends with an outlook on future questions and tasks. It is concluded that future controlled clinical trials should, in a next step, focus on such known protocols, and be designed along the lines of learning theory.

Attention-Deficit/Hyperactivity Disorder (ADHD) has become one of the most common neurodevelopmental and psychiatric dis- orders of childhood. The general rate of prevalence is reported between 3% and 7% of school age children (Cormier, 2008). In 40–60% of all cases ADHD persists into adolescence and adult- hood (Faraone, Biederman, & Mick, 2006). Currently, the disorder is primarily diagnosed by referring to the criteria of the Diagnos- tic and Statistical Manual of Mental Disorders (DSM-IV) or the International Statistical Classification of Mental Disorders (ICD- 10). According to the DSM-IV, the disorder presents itself in three primary subtypes: predominantly inattentive type, predominantly hyperactive-impulsive type and the combined type. Therefore the core symptoms of ADHD consist of inattention, impulsivity and hyperactivity.

Currently, both stimulant medication and behaviour ther- apy are the most often applied and accepted treatments for ADHD. However, recent large-scale studies and meta-analyses have demonstrated limitations of these treatments. For example, limited long-term effects of stimulant medication (possibly the result of an up-regulation of the Dopamine Transporter (DAT) (Wang et al., 2013)) and behaviour therapy have been reported (Molina et al.)