Dopamine and Insulin in Psychosis

Schizophrenia is a severe psychiatric disorder that occurs in approximately 1% of the general population and, at times, imposes lifelong hardship on those affected and their families. The acute phase of the disorder manifests in symptoms such as hallucinations, delusions, or disordered thinking, collectively named psychosis. Patients suffering from this disorder also have a higher risk of developing diabetes and similar metabolic conditions, which can in turn lead to heart complications and a significantly reduced lifespan. Many symptoms of schizophrenia can be linked to changes in brain dopamine levels, and medication that targets dopamine receptors works well in treating psychosis but can have unwanted effects such as weight gain or high blood sugar, thus adding to already present metabolic problems. This is not surprising, as dopamine, a chemical best known for its role in motivation and goal-directed actions, also plays a part in many vital functions, one of which is metabolism. Dopamine responds to changes in available energy by guiding behavior according to what the body needs, and is directly involved in various metabolic processes both in the brain and in organs such as the pancreas. In particular, dopamine has a mutually suppressing relationship with insulin, a hormone that primarily regulates blood glucose levels but is also crucial for memory, learning, and other cognitive abilities. This study builds on evidence that altered dopamine function and metabolic disturbances seen in schizophrenia are connected and tries to clarify the nature of their link. To do this, we will focus on the relationship between dopamine and insulin at the onset of illness. By using nasally applied insulin as an intervention and two brain imaging methods positron emission tomography and magnetic resonance spectroscopy - to measure dopamine and glucose levels, we will determine if brain insulin actions are impaired in psychosis. If, as there is reason to believe, the communication between insulin and dopamine is disrupted, this could be a key factor contributing to both metabolic and psychological symptoms of the disorder. The results of the study will therefore significantly advance our understanding of the metabolic aspects of schizophrenia and may have important implications for future developments in treatment and prevention.