Posttraumatic stress disorder is a debilitating psychiatric disorder characterized by symptoms of intrusive re-experiencing of trauma, avoidance and hyper-arousal. Diagnosis and treatment of PTSD is further complicated by concurrently occurring disorders, the most frequent being major depressive disorder and anxiety disorders. Previous research highlights that attentional processing in posttraumatic stress disorder is associated with substantial interference by emotional stimuli, a phenomenon also observed in these concurrently occurring psychiatric disorders. However, the diagnosis-relevance of this interference remains elusive. Here, we investigated the emotional Stroop interference for diagnosis-related stimuli, generally negative stimuli, and generally positive stimuli in posttraumatic stress disorder, major depressive disorder and anxiety disorders. We performed a systematic database search in PubMed (Medline), Cochrane Library and PsycINFO on emotional Stroop performance in individuals with a diagnosis of posttraumatic stress disorder, major depressive disorder or anxiety disorders separately. Mean effect sizes, standard errors and confidence intervals were estimated for each clinical group and healthy control group comparison using random effect models. As compared to healthy control group, the posttraumatic stress disorder group displayed greater interference by diagnosis-related stimuli and positive stimuli but not for generally negative stimuli. The major depressive disorder and anxiety disorders groups showed greater interference by diagnosis-related and negative stimuli, but not by positive stimuli. The age and sex had no significant impact on interference. These findings highlight the importance of diagnosis-relevant information on attentional processing in all three clinical populations, posttraumatic stress disorder, major depressive disorder and anxiety disorders. Further, the impact of generally negative stimuli but not generally positive stimuli in major depressive disorder and anxiety disorders indicate impaired attentional bias for mood-congruent stimuli but not for general stimuli. Finally, it remains to be studied whether the influence of generally positive stimuli in posttraumatic stress disorder indicate that positive stimuli are perceived as PTSD related.

Schizophrenia is a severe and frequent neuropsychiatric disorder. Despite antipsychotic medications, up to 30% of patients with schizophrenia still report disabling treatment-resistant symptoms. Transcranial direct current stimulation (tDCS) has been proposed as a novel method to alleviate such symptoms. Here, we review studies investigating the effects of tDCS on symptoms, cognition, brain activity and cortical plasticity in patients with schizophrenia. We provide an up-to-date and comprehensive overview of the use of tDCS in patients with schizophrenia. More specifically, we first present the effects of tDCS on treatment-resistant symptoms of schizophrenia. We report that tDCS applied over the frontotemporal regions reduced auditory hallucinations, with a mean 34% reduction of symptoms. Moreover, tDCS applied over both prefrontal cortices reduced negative symptoms and catatonia. We discuss the need for further sham-controlled studies to confirm these effects. Second, we present the impact of tDCS on cognitive functions in patients with schizophrenia. Positive effects of tDCS have been reported on learning, working memory, attention and source-monitoring. Third, we review the effects of tDCS on brain activity in patients with schizophrenia. Although only few studies investigated the effects of tDCS using neuroimaging technics, these studies are helpful at identifying the mechanisms of action of tDCS in schizophrenia. Fourth, we present tDCS studies on cortical plasticity showing reduced cortical plasticity in patients with schizophrenia that tDCS may beneficially modulate. Lastly, we discuss the safety aspects of tDCS in patients with schizophrenia and potential directions to improve efficacy for this clinical populations.

The dorsolateral prefrontal cortex (DLPFC) is often targeted with noninvasive brain stimulation (NIBS) to modulate in vivo human behaviors. This brain region plays a key role in mood, emotional processing and attentional processing of emotional information. In this article, we ask the question: when we target the DLPFC with NIBS, do we modulate these processes altogether, nonspecifically, or can we modulate them selectively? We thus review articles investigating the effects of NIBS applied over the DLPFC on mood, emotional processing and attentional processing of emotional stimuli in healthy subjects. We discuss that NIBS over the DLPFC can modulate emotional processing and attentional processing of emotional stimuli, without specifically influencing mood. Indeed, there seems to be a lack of evidence that NIBS over the DLPFC influence on mood in healthy individuals. Finally, there appears to be a hemispheric lateralization: when applied over the left DLPFC, NIBS improved processing of positive stimuli and reduced selective attention for stimuli expressing anger, whereas when applied over the right DLPFC, it increased selective attention for stimuli expressing anger.