Anhedonia, the reduced ability or motivation to experience pleasure, is one of the main clinical symptoms shared by a wide range of neuropsychiatric and brain disorders such as schizophrenia and depression. It has also been considered to be an important biomarker for schizophrenia spectrum disorders and related disorders. However, anhedonia and related clinical features such as amotivation and avolition have been found to be not very responsive to antipsychotic medications in schizophrenia spectrum disorders. Similarly, medical treatment for depressive patients is not very satisfactory. Recent studies have been focusing on the non-pharmacological intervention.

Dr. Raymond Chan’s team from the Neuropsychology and Applied Cognitive Neuroscience Laboratory, Key Laboratory of Mental Health, Institute of Psychology of Chinese Academy of Sciences has recently conducted a meta-analysis and demonstrated that the neural substrates of working memory overlap with the hedonic processing at the prefrontal-striatal system in both healthy individuals and patients with schizophrenia. Based on this evidence, Dr. Chan and his team members have further developed a working memory training involving both visual and auditory components to specifically examine its transfer effect to improve the cognitive processing and neural mechanism of anhedonia in individuals with social anhedonia.

The first study recruited 17 individuals with social anhedonia to participate a 20 sessions (20 minutes per session; five days a week for four weeks) of working memory training involving both audio and visual stimuli. Computer and neuropsychological tests that specifically captured the working memory and hedonic processing were administered to these individuals before and after the completion of the training. Another 17 individuals with social anhedonia who did not complete the working memory training were also recruited and assessed at the baseline time point and four week later. The findings showed that individuals with social anhedonia and received the working memory training showed significant improvement in both working memory performances and task capturing hedonic processing. However, individuals with social anhedonia had not received the training did not show the corresponding working memory and hedonic processing improvement.

The second study further examined the underling neural mechanism for the corresponding changes of hedonic deficits with the above-mentioned working memory training programme. Dr. Chan and his team recruited another 15 individuals with social anhedonia to complete the training programme. The individuals also underwent the brain scans while they were performing two functional imaging tasks that captured the hedonic processing on monetary and affective stimuli before and after the training to evaluate the neural transfer effects of the working memory training. The results showed that significant brain activations related to anticipation of both monetary and affective rewards were observed. Enhanced brain activations were observed at the anterior cingulate cortex, the left dorsal striatum and the left precuneus regions for the anticipation of affective rewards, whereas enhanced brain activations were observed at the dorsolateral prefrontal cortex and the supramarginal gyrus for the anticipation for monetary rewards.

Taken together, these findings suggest the transfer effect of working memory training involving cross-modalities components to enhance hedonic processing in individuals with social anhedonia. Similar behavioural manifestations but distinct neural mechanisms were found in monetary-based and affective-based hedonic processing. These findings highlight the importance of non-pharmacological interventions to improve anhedonia in clinical and subclinical populations. Dr. Chan’s team is now applying this training programme to various clinical populations with anhedonia symptoms.

These studies were conducted by Dr. LI Xu under the supervision of Dr. Raymond Chan, and were supported by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences, the Beijing Municipal Science & Technology Commission Grant, the Beijing Training Project for the Leading Talents in S & T, the National Natural Science Fund China, and the CAS/SAFEA International Partnership Programme for Creative Research Teams the Key Laboratory of Mental Health.

These studies have been published online in Scientific Reports, Psychiatry Researchand .Neuropsychologia

Other related articles: Distinct processing of social and monetary rewards in late adolescents with trait anhedonia

                                    Domain-specific deficits towards social affective but not monetary incentives in social anhedonia