Lay Summary (English)

Social interaction plays an important role in our physical and mental health. A disturbance in social behavior can lead to all kinds of disorders, including cardiovascular disease and an increased chance of dying earlier. A disturbance in social behavior can occur in various ‘neuropsychiatric’ diseases, such as Alzheimer’s disease and schizophrenia. Although these two syndromes are very different from each other, there are similarities in the way on which disrupted social behavior manifests itself. In recent years, the PRISM project has investigated the similarities in disrupted social behavior in these two syndromes. It was also investigated how disrupted social behavior is reflected in the brain.

The PRISM study looked at two very different neuropsychiatric syndromes from a ‘transdiagnostic’ perspective. Transdiagnostic means that the focus is not so much on separate syndromes, but more on the underlying symptoms of these illnesses. Just as a fever can be a sign of an infection, the flu or something else, disrupted social behavior can also be a symptom of very different diseases.

Disrupted social behavior is usually defined in different ways for different syndromes. In depression, disrupted social behavior is often seen as a lack of experiencing joy (also called ‘anhedonia’), in schizophrenia it is seen as part of a flattening of emotions and initiative (also called ‘negative symptoms’), and in Alzheimer’s disease it is often seen as a result of guilt and shame from the memory loss. PRISM focuses on the similarities in disrupted social behavior in these diseases.

The questionnaire study shows that disrupted social behavior manifests itself in the same way in patients with schizophrenia and Alzheimer’s disease. The brain scan research also shows that communication between the different brain regions within the so-called ‘resting state brain network’ is less efficient in people with disrupted social behavior compared to people with normal social behavior. It also appears that the entire ‘resting state brain network’ works less efficiently in disrupted social behaviour. This happens independently of the specific syndrome that causes the disturbance in social behaviour. That is a surprising finding. It means that disturbed social behavior is expressed in the same way at the brain level in both schizophrenia and Alzheimer’s disease.

In summary, the PRISM study shows that there are clear similarities in disrupted social behavior in very different disease states. The results thus show that it is useful to look at disrupted social behavior from a transdiagnostic perspective. This also means that there are exciting opportunities to look for the best way to diagnose and modify disrupted social behaviour, regardless of which clinical picture underlies the disturbance in social behaviour.