Official announcement: Disputas: Lynn Mørch-Johnsen
Title of trial lecture
"What is the evidence for and against a similar origin of bipolar disorder and schizophrenia?"
Thesis summary
Characterizing the neuropathology of psychotic disorders is imperative to develop better and more specific treatment. Previously, abnormalities in brain structure have been shown in schizophrenia and bipolar disorder. The aim of the thesis was to investigate the relationship between in vivo brain structure and the core symptoms apathy and auditory hallucinations in psychotic disorders.
The study samples included patients with first-episode psychosis, schizophrenia and bipolar disorder participating in the Thematically Organized Psychosis (TOP) project (University of Oslo, Norway). Participants underwent clinical interviews as well as 1.5 T Magnetic Resonance Imaging (MRI) of the brain. The FreeSurfer software was used to estimate brain structure measures from T1 weighted MRI. Associations between brain structure measures and auditory hallucinations and apathy were investigated using linear regression models.
First-episode psychosis patients with persistent apathy had thinner cortex in the anterior cingulate cortex and the orbitofrontal cortex compared to first-episode patients without persistent apathy. In schizophrenia patients, a lifetime history of auditory hallucinations was associated with thinner cortex in the primary auditory cortex. In bipolar disorder patients, a lifetime history of auditory hallucinations was associated with thicker cortex in the primary auditory cortex and in a small region in the superior parietal lobule.
The results demonstrate specific brain structure abnormalities associated with persistent apathy and auditory hallucinations in psychotic disorders, and emphasize a need to focus on specific symptoms, not just diagnosis, when searching for neuropathological substrates of psychotic disorders. Auditory hallucinations may be associated with different underlying mechanisms in schizophrenia and bipolar disorder.