Official announcement: Disputas: Kristina Cecilie Skåtun
Thesis summary
Schizophrenia and bipolar disorder are severe mental disorders with party overlapping symptomatology. Mounting evidence from neuroimaging studies point to altered interactions, or connectivity, between brain regions in these patient groups. A characterization of brain networks and their interaction may therefore provide novel information about the pathophysiology of these disorders.
In this thesis, advanced neuroimaging methods were used to characterize brain networks during rest in a large subject sample. The main aims were to increase our understanding of functional brain connectivity in patients, characterize abnormal connections and unique and overlapping features between schizophrenia and bipolar disorder, and to assess the clinical utility of altered functional brain connectivity by individual classification of patients and controls.
Results showed altered functional brain connectivity in patients, with more substantial changes in schizophrenia. Results implicated sensory and frontal regions in patients, particularly in schizophrenia, suggesting both aberrant sensory processing and deficits in regions important for cognition. Also, the thalamus was affected, where a disrupted communication flow to the frontal lobe may affect cognitive processing, and where an increased connectivity to sensory regions may be responsible for some of the disruptions of the senses, like auditory hallucinations. Moreover, reduced limbic connectivity in both patient groups highlights the deficiencies in the brain’s mood-circuits. Lastly, connectivity changes were robust across two scan sites with good classification accuracies, indicative of common brain alterations in schizophrenia.
Overall, this thesis demonstrates that schizophrenia and bipolar disorder are characterized by deficient information processing between sensory, limbic, thalamic, and frontal regions. These findings provide increased knowledge about pathophysiological mechanisms in severe mental illness.