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19-03-2013 | Mental health | Article

White matter disruptions distinguish non-deficit schizophrenia

Abstract

Free abstract

medwireNews: Disruption in white matter tracts can be considered a hallmark neurobiologic feature for distinguishing patients with deficit schizophrenia from those with non-deficit schizophrenia, suggest findings published in JAMA Psychiatry.

Aristotle Voineskos (Centre for Addiction and Mental Health, Toronto, Ontario, Canada) and colleagues say the findings "support the fact that white matter disruption in these patients is a feature of the clinical deficit subtype, rather than other factors such as long-term medication exposure or duration of illness."

The study findings also showed that, compared with healthy individuals, cortical thickness reductions were present in the same regions in both deficit and non-deficit schizophrenia patients. The researchers say this additional finding supports the consistency of cortical thickness findings in different clinical subtypes.

The researchers performed a cross-sectional high-resolution magnetic resonance neuroimaging study of 77 patients with schizophrenia and 79 healthy controls.

To strengthen the validity of the study, the researchers used an individually matched approach (18 patients with deficit schizophrenia, 18 with non-deficit schizophrenia, and 18 healthy controls) and an unmatched population-based approach (18 patients with deficit schizophrenia, 59 patients with non-deficit schizophrenia, and 79 healthy controls).

In both study approaches, patients with deficit schizophrenia demonstrated white matter tract disruptions at the right inferior longitudinal fasciculus, right arcuate fasciculus, and left uncinate fasciculus, when compared with non-deficit schizophrenia patients and healthy individuals

The researchers say the findings are of importance, given that these white matter tracts form neural circuitry connecting regions involved in emotion expression, processing, and socioemotional function, which are characteristically impaired in deficit patients.

Cortical thickness reductions seen in both deficit and non-deficit schizophrenia patients, but not in healthy individuals, occurred in the orbitofrontal cortex, middle and superior temporal gyri, dorsolateral prefrontal cortex, parahippocampal gyrus, and occipitotemporal cortex.

"Our data support the contention that cortical thickness reduction in these regions is a characteristic feature of the clinical syndrome of schizophrenia," say Voineskos and team.

To rule out the influence of medication effects, illness duration, or other possible confounding factors, a post-hoc analysis of 20 patients with first-episode schizophrenia was performed. Findings revealed that deficit scores were strongly correlated with disruption in the same white matter tracts, further supporting the initial study findings.

"These results point to white matter tract disruption as a neurobiologic marker of the deficit clinical subtype and offer a paradigm for reduced heterogeneity in psychiatric diseases," conclude the authors.

medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013

By Ingrid Grasmo, medwireNews Reporter

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