Neuroimaging of Schizophrenia: The Importance of Illness Severity and Duration

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Researchers used voxel-based morphometry, which allows examination on a voxel-wise basis across the whole brain, to assess whether structural abnormalities in schizophrenia are static or progressive.
Researchers used voxel-based morphometry, which allows examination on a voxel-wise basis across the whole brain, to assess whether structural abnormalities in schizophrenia are static or progressive.

Intensive neuroimaging research efforts have resulted in findings that indicate the presence of generalized tissue loss within the brain parenchyma among individuals diagnosed with neuropsychiatric disorders such as schizophrenia. It is currently unclear, however, whether the observed structural brain abnormalities are static or progressive/dynamic.

To further explain this long-standing question, investigators first combined the multisite, cross-sectional structural magnetic resonance imaging (MRI) data, and then used a voxel-based morphometry (VBM) analysis technique to assess global and regional gray matter volumes in 99 patients diagnosed with chronic schizophrenia and in 62 individuals diagnosed with first-episode schizophrenia. Data were then compared to those collected from 151 typical, healthy control participants.

In terms of total gray matter volume or white matter volume, patients in either schizophrenia group did not differ significantly compared with the control group of participants. Patients with schizophrenia did, however, present with higher CSF volumes. Also, patients with chronic schizophrenia presented with higher CSF volumes compared to individuals with first-episode schizophrenia, but once the effect of age of onset was accounted for, this difference was no longer statistically significant.

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When compared with control participants, patients in either schizophrenia group presented with statistically significant regional gray matter volume reductions. In line with previous reports, compared with controls, individuals with first-episode schizophrenia had subtle, yet statistically significant reductions in gray matter volume across several brain regions including the insula, hippocampus, amygdala, and striatum. Compared with individuals with first-episode schizophrenia, patients with chronic schizophrenia presented with even more widespread gray matter deficits across numerous brain regions including the bilateral superior, inferior, and orbital frontal cortices, right middle frontal cortex, bilateral anterior cingulate cortices, bilateral insulae, and right superior and middle temporal cortices.

According to investigators, this more extensive deficit that was observed in patients with chronic schizophrenia may be due to illness severity and/or illness chronicity. In other words, the “relative [gray matter] volume deficits may be greater in (presumably more severe) cases with earlier age of onset, as well as varying as a function of illness duration in specific frontal brain regions,” the authors concluded.

Reference

Torres US, Duran FL, Schaufelberger MS, et al. Patterns of regional gray matter loss at different stages of schizophrenia: a multisite, cross-sectional VBM study in first-episode and chronic illness. Neuroimage Clin. 2016;12:1-15.

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