A team from the University of Geneva (UNIGE) and the Geneva University Hospitals (HUG) has described for the first time the interaction between the cerebellum and the brain's reward system in individuals with schizophrenia. This interaction is linked to the "negative symptoms" of schizophrenia, which include apathy, social withdrawal, and lack of motivation.
Key Findings
Schizophrenia, a neuropsychiatric disorder affecting about 1% of the population, is characterized by symptoms such as hallucinations and delusions, but also by significant negative symptoms. Abnormalities in the brain's reward system, particularly in the dopamine-producing ventral tegmental area (VTA), have been associated with these negative symptoms. In schizophrenic patients, VTA overactivity is thought to contribute to a blunted perception of salience.
This study, published in Biological Psychiatry, involved following 146 patients for 3 to 9 months and using an independent validation cohort. The research demonstrated that the cerebellum plays a crucial role in regulating this VTA-mediated mechanism. Stronger cerebellar regulation of the reward system was associated with a reduction in negative symptoms, while weaker regulation correlated with an increase in symptoms.
Therapeutic Implications
Unlike the VTA, which is located deep within the brain, the cerebellum is more superficially positioned, making it a more accessible target for non-invasive interventions. Researchers are exploring the potential of transcranial magnetic stimulation (TMS) to stimulate and strengthen cerebellar activity to modulate the identified cerebellum-VTA circuit. A randomized controlled trial funded by the Leenaards Foundation and the Fondation Privée des HUG is currently underway to evaluate this approach, with results anticipated in 2028.