Brain volume differences may help predict bipolar disorder
MedWire News: Patients at ultra-high risk for psychosis who go on to develop the bipolar disorder show greater amygdala and insula volume reductions than ultra-high risk patients who remain well, say researchers.
Writing in Psychiatry Research: Neuroimaging, lead author Stephen Wood (University of Birmingham, UK) and team explain that "while disease-related neuroanatomical abnormalities have been identified in bipolar disorder, it remains unclear whether these abnormalities predate the onset of the illness."
To investigate, the team studied data from magnetic resonance imaging (MRI) brain scans of 22 young people, aged an average of 20 years, at ultra-high risk for psychosis and 11 age-, gender, and handedness-matched mentally healthy individuals (controls).
Among the patients in the ultra-high risk group, 11 subsequently developed bipolar disorder, at a median time to onset of 328 days, and 11 remained well over a follow up of at least 12 months.
Results from the MRI scans revealed no significant differences among the three groups regarding whole-brain, intracranial, hippocampal, and lateral ventricle volumes.
However, among the ultra-high risk group, those who subsequently developed bipolar disorder had smaller mean left and right amygdala volumes than those who remained well, at 1348 versus 1486 mm3, and 1267 versus 1517 mm3, respectively, after correction for intracranial volume.
Ultra-high risk patients who subsequently developed bipolar disorder also had, on average, smaller insula volumes than ultra-high risk patients who remained well.
Wood et al conclude: "Our cross-sectional data raise the possibility that MRI or other investigations could help to distinguish people with existing subthreshold psychotic symptoms who will subsequently develop bipolar disorder from those who will not, although at present it is too early to say whether MRI will prove to be usable as a diagnostic tool."
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By Mark Cowen