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Neural pathways and interventions in anhedonia

Anhedonia refers to a reduced ability to experience pleasure and happiness

At the International Schizophrenia Research Society (SIRS) Symposium 2023, Professor Raymond Chan (Institute of Psychology, Chinese Academy of Sciences, China) spoke about some of the neural circuits associated with pleasure/reward pathways that have been identified using brain mapping. He also described interventions that target the functioning of these neural pathways as showing promise in efforts to improve the state of anhedonia. ¹

The reward process is described as consisting of four components: expectation, consumption, learning, and effort computation. ¹ Brain mapping of the pathways of these components of the reward process in patients with schizophrenia showed significant deactivation in the cingulate cortex associated with reward anticipation; deactivation of the left IV/V region of the cerebellar lobule, the right insula and the right inferior frontal gyrus - related to the "consumption" of rewards; decreased activation in the right putamen, right thalamus, and left cerebellar peduncle, which is associated with reward "learning," as well as decreased activation of the ventral striatum, as well as deactivation of the caudate nucleus, cingulate cortex, prefrontal lobe, and parietal areas - at "calculation of efforts". ¹

An improved understanding of the neural mechanisms underlying anhedonia will contribute to the development of adjunctive treatment approaches to its resolution

Further multimodel analyzes of reward anticipation and reward learning revealed common functional brain impairments in cortical, subcortical, and cerebellar regions.

Mapping of brain activation in healthy monozygotic and dizygotic twins during a delayed monetary incentive task showed that the experience of pleasure and anhedonia were significantly correlated with activation of the nucleus accumbens (NAcc). Participants who received training (improving motivation through real-time MRI-based NAcc functional self-regulation) showed improvements in reward circuitry. No improvement was observed in participants who did not undergo training. ¹

Participants who completed the training program showed improved functioning of the reward circuits in their brains

Perspective is defined as the ability to "pre-experience" the future by modeling it in our minds. Affective forecasting is defined as the ability to predict one's emotional feedback in the future. Both of these processes are blunted in patients with schizophrenia. Brain mapping demonstrated reduced functional connectivity with the retrosplenial cortex ROI in anhedonic patients compared to controls. A potential driver of high levels of social anhedonia in patients showed improved connectivity between the right caudate and inferior occipital gyrus. ¹

Patients with schizophrenia have a reduced ability to "pre-experience" the future, simulating it in their minds

Future directions of research

Dr. Chan introduced the audience to the Mental Health International League (SMILE), a research network for transdiagnostic and subclinical groups. This is an international collaboration dedicated to the study of biomarkers, psychopathology and interventions in mental health disorders. He also introduced the audience to the International Schizotypy Research Consortium, a consortium created in 2013 to bring researchers together to collaborate and participate in research and development.

Dr. Chan's ultimate goal is to develop tools to improve anhedonia in patients with schizophrenia, and to find ways to prevent the development of mental illness in at-risk individuals. ¹