medwireNews: Functional and anatomic changes affect separate parts of the brain in antipsychotic-naïve patients with first-episode schizophrenia, shows an imaging study.
Researchers who performed functional magnetic resonance imaging (fMRI) on 100 patients with schizophrenia found that they had decreased brain activity in the right inferior and left superior frontal gyrus, the medial frontal gyrus bilaterally, the inferior parietal lobule bilaterally, and the precuneus, relative to 100 mentally healthy controls. They also had bilaterally increased activation in the putamen and occipital areas.
The affected areas involve brain networks believed to be important for decision making, working memory, and general monitoring of people's environments, say the researchers.
But analysis of T1-weighted volumetric images showed no anatomic differences in these areas. Instead, the patients had increased gray matter in the left and right thalamus, and the anterior cingulate cortex, insula, and orbital frontal gyrus, as well as decreased gray matter in the left paracentral and left inferior parietal lobules.
"One possible explanation is that fMRI may reflect physiological alterations related to acute psychosis, while changes in brain anatomy reflect more stable and long-standing alterations," suggest Qiyong Gong (West China Hospital of Sichuan University) and colleagues.
However, neither anatomic nor functional changes correlated with the duration of untreated psychosis, the severity of psychotic symptoms, including positive symptoms on the Positive and Negative Syndrome Scale (PANSS), or the presence of negative symptoms.
"While the possibility that fMRI changes more directly reflect psychosis-related neurophysiological changes is appealing, the lack of correlation with positive symptoms on the PANSS and with illness duration suggests that BOLD [blood-oxygen-level-dependent] signal alterations may better track the presence than the severity or duration of psychosis," says the team.
Of note, patients with marked negative symptoms (PANSS negative symptom subscale ≥20) had increased gray matter volume in the middle frontal gyrus bilaterally and the left superior frontal gyrus, relative to those with less severe negative symptoms.
This finding may also help to explain why some other studies have found only reductions in gray matter in schizophrenic patients, the researchers suggest, if those studies had a small proportion of patients with prominent negative symptoms (36% in the current study).
Overall, "these findings suggest a relatively static or slowly evolving process of anatomical changes, which is consistent with a recent study of treated schizophrenia patients in suggesting the absence of progressive loss of gray matter volume during the early illness course before treatment has begun," writes the team in the American Journal of Psychiatry.
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