I thought we already knew this, but here goes:
Schizophrenia may blur the boundary between internal and external realities by over-activating a brain system that is involved in self-reflection, and thus causing an exaggerated focus on self, a new MIT and Harvard brain imaging study has found.
The traditional view of schizophrenia is that the disturbed thoughts, perceptions and emotions that characterize the disease are caused by disconnections among the brain regions that control these different functions.
But this study, appearing Jan. 19 in the advance online issue of the Proceedings of the National Academy of Sciences, found that schizophrenia also involves an excess of connectivity between the so-called default brain regions, which are involved in self-reflection and become active when we are thinking about nothing in particular, or thinking about ourselves.
“People normally suppress this default system when they perform challenging tasks, but we found that patients with schizophrenia don’t do this,” said John D. Gabrieli, a professor in the McGovern Institute for Brain Research at MIT and one of the study’s 13 authors. “We think this could help to explain the cognitive and psychological symptoms of schizophrenia.”
Gabrieli added that he hopes the research might lead to ways of predicting or monitoring individual patients’ response to treatments for this mental illness, which occurs in about 1 percent of the population.
Schizophrenia has a strong genetic component, and first-degree relatives of patients (who share half their genes) are 10 times more likely to develop the disease than the general population. The identities of these genes and how they affect the brain are largely unknown.
The researchers thus studied three carefully matched groups of 13 subjects each: schizophrenia patients, nonpsychotic first-degree relatives of patients and healthy controls. They selected patients who were recently diagnosed, so that differences in prior treatment or psychotic episodes would not bias the results.
The subjects were scanned by functional magnetic resonance imaging (fMRI) while resting and while performing easy or hard memory tasks. The behavioral and clinical testing were performed by Larry J. Seidman and colleagues at Harvard Medical School, and the imaging data were analyzed by first author Susan Whitfield-Gabrieli, a research scientist at the MIT Martinos Imaging Center at the McGovern Institute.