New Study Uncovers Serotonin's Unexpected Role in Worsening Schizophrenia Symptoms

A recent study has found that increased serotonin activity in specific brain regions may significantly contribute to the worsening of negative symptoms in schizophrenia, hindering patients' recovery and social integration.

Schizophrenia is a complex mental disorder affecting approximately 1% of the global population, with primary negative symptoms including social withdrawal, lack of motivation, anhedonia, and reduced capacity to carry out daily activities.

Despite advancements in pharmacological treatments, these symptoms remain among the most challenging to address.

For the first time, researchers at the Institute of Psychiatry, Psychology and Neuroscience at King's College London have tested a hypothesis proposed over sixty years ago, suggesting that hyperactivity of the serotonin system could be responsible for these symptoms. The study involved 54 participants, including 26 diagnosed with schizophrenia and 28 healthy controls.

Participants underwent two tests using positron emission tomography (PET), employing a radioactive substance that binds to serotonin receptors in the brain.

During the tests, participants received a dose of d-amphetamine to stimulate serotonin release.

Results indicated a general decrease in radioactive binding to serotonin receptors across all participants, suggesting an increase in the release of this neurotransmitter. However, the increase was significantly more pronounced in patients with schizophrenia, particularly in the prefrontal cortex, which is responsible for planning, decision-making, and motivation.

Analysis also revealed a direct correlation between increased serotonin release and the severity of negative symptoms and functional impairment in patients, indicating that this neurotransmitter may complicate the course of the illness rather than improve it, challenging the common belief that it is merely the "happiness hormone."

While serotonin is known for its central role in regulating mood, sleep, cognitive functions, appetite, and social behavior, this study highlights that an imbalance in its levels—rather than just a decrease—could be a pathological factor in certain mental disorders.

Researchers believe these findings may pave the way for new therapeutic strategies aimed at more precisely regulating serotonin activity, rather than broadly increasing it, potentially enhancing the quality of life for patients with schizophrenia in the future.