In the past, research on the biological origins of psychiatric illnesses has focused on individual diagnostic categories that are studied in isolation. However, there is mounting evidence indicating that normally distinct psychiatric diagnoses are not separated by clear neurobiological boundaries.
Researchers from McLean Hospital (MA, USA) and Yale University (CT, USA) have published findings of their study of large-scale systems in the brain, which could improve our understanding of the symptoms and causes of bipolar disorder, schizophrenia, depression and other mental illnesses.
According to lead author, Justin Baker (McLean Hospital), the study “took a birds-eye view to look into the ways large-scale systems in the brain interact with one another.”
Within the study, which has been published in the Proceedings of the National Academy of Sciences, the investigators used functional magnetic resonance imaging (fMRI) data from more than 1000 individuals, including individuals who had been diagnosed with conditions such as bipolar disorder, schizophrenia and depression.
Information was collected through rest scans, in which participants were asked to lie in a scanner with their eyes open, allowing researchers to capture data about spontaneous fluctuations in the brain.
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“For most studies, illnesses are studied in isolation, but evidence strongly suggests that distinct psychiatric diagnoses are not separated by clear neurobiological boundaries,” explained Baker.
“The approach we’ve taken is to look at the whole brain so you can see not only how individual systems – like the visual system and motor system – are functioning, but how higher order systems – like cognitive systems – are functioning in the brain to see if there are correlations.”
According to Baker, this study is significant because we don’t have any objective measures of psychiatric illnesses that allow us to verify a patient’s reports about their symptoms (i.e., there are no vital signs in psychiatry).
The current work, however, allows for “brain ‘fingerprinting’ to try to address what changes in the brain are shared across illnesses and what aspects might be specific to different illnesses,” stated Baker. “This work points to evidence at a high level that there are very profound changes in the brain that could start to serve as an objective biomarker.”
The researchers believe that this study is beginning to give us a better way of seeing how schizophrenia, bipolar disorder and depression are similar or have shared underlying causes.
Additionally, Baker explained that prior research has indicated “that there is significant genetic risk for schizophrenia and bipolar disorder, and we also know that these conditions affect certain parts of the brain, but this study highlights that one system is affected or disrupted as a function of how severe the illness is, irrespective of whether it was psychosis or an affected illness like depression.”
Baker and colleagues plan to build on this research through studies into the functioning of large-scale brain systems related to obsessive compulsive disorder and trauma, and longer-term investigations.
“We want to see if there is a fingerprint for different conditions and then use that information and apply it to the individual. We are conducting studies that follow individuals over time to look at the brain to see how symptoms are changing. We’re trying to go from the snapshot view of these biomarkers to something that is much more dynamic and captures changes and nuances,” Baker concluded.
Sources: Baker JT, Dillon DG, Patrick LM et al. Functional connectomics of affective and psychotic pathology. Proc. Natl Acad. Sci. 116(18), 9050–9059 (2019); www.mcleanhospital.org/news/brain-researchers-seek-fingerprints-severe-mental-diseases