Official announcement: Disputas: Beathe Haatveit
Thesis summary
Beathe Haatveit has within this doctoral work studied cognition in psychotic disorders, with a particular focus on schizophrenia.
Schizophrenia is a severe mental illness characterized by positive and negative symptoms, as well as cognitive dysfunctions such as executive impairments affective daily function. Through three separate studies the current thesis aimed to assess a broad spectrum of executive sub-functions and to investigate the sameness and uniqueness across these functions, using both neurocognitive assessment and functional brain imaging.
Overall, we found that patients with broad spectrum schizophrenia disorders had dysfunctions in a wide-range of executive sub-functions including working memory, fluency, flexibility, and inhibitory control. These impairments were already present in first episode psychosis patients and generally stable over the first year. Furthermore, we found that the 2-back d´ was the preferred measure of working memory in our test-battery compared to the Letter Number Sequencing test and the Digits Span Backward test. The 2-back d´ has the advantage of capturing working memory disabilities in our patient sample, as well being less influenced by demographic factors or IQ. When studying the underlying network activation during executive processing, we found that patients with schizophrenia had abnormal recruitment of the default mode network across the two tasks. Additionally, whereas activation of the task-positive network was associated with performance across executive tasks, no such association was found in the default mode network.
Taken together, we have documented patient-control differences across a variety of executive function tests that remained stable over the first year of treatment in patients with first episode psychosis. Furthermore, we found a general default mode network dysregulation that was not merely an epiphenomenon of cognitive dysfunction in patients.