The Effects of Emotional Expressions on Attention-Inhibition Processes of Depressed Patients: An ERP Systematic ReviewAuthor(s): Daniel Kwasi Ahorsu, Hector WH Tsang
Major Depressive Disorder (MDD) affects millions of people across the lifespan and causes tremendous burden across the globe. Abnormalities in cognitive functions, including decreased cognitive processing speed, trouble concentrating, and biases towards emotional expressions are major reasons of the debilitating effects of MDD. This systematic review aims to examine the attention-inhibition processes of MDD patients (without comorbidity) in comparison to healthy controls (HCs) based on emotional expressions, using a multistaged Information Processing Model. An online search was conducted in EBSCO, PubMed, ScienceDirect, and Wiley from inception to September 2017. Ten studies were extracted for a detailed review. Behavioural and electrophysiological results reveal that depressed patients are hypersensitive towards negative or sad emotional stimuli but hyposensitive towards positive or happy emotional stimuli. The bias is stronger in MDD when the patients are symptomatic but there is a ‘transition’ from negative emotional bias to positive emotional bias during remission. This bias is also observed at the early/perceptual processing stage, mid/ post-perceptual processing stage, and late/central processing stage. Based on the results, it is recommended that, first, future studies should examine the number of stages involved in information processing in addition to examining which stage remains unaffected by MDD. Second, studies should examine the reasons behind this negativity bias as well as the association between ERP components and daily functions among MDD patients so as to get a holistic view of their condition. Third, ERP studies can investigate in what ways antidepressants improve the information processing and negative bias in MDD patients.