Reductions in cortical thickness do not progress with schizophrenia duration
MedWire News: Deficits in cortical thickness among patients with schizophrenia do not progress significantly over the course of the illness above those commonly associated with aging, and may instead reflect pathological processes around the time of illness onset, say Japanese researchers.
"Global gray matter reductions in schizophrenia have been consistently reported," explain Manabu Kubota (Kyoto University) and team. "In addition, regional gray matter reductions have been demonstrated by studies using region of interest approaches and voxel-based morphometry techniques, particularly in prefrontal and temporal regions."
But they add: "Although some of these alterations are already exhibited prior to illness onset, whether or not these anatomical brain alterations are progressive remains unclear."
To confirm previous reports of reduced cortical thickness in schizophrenia patients, and to investigate whether such deficits progress with duration of illness, the researchers studied 83 patients with the mental health disorder, aged between 18 and 55 years, and 90 age-, gender- and education-matched mentally healthy controls. Of the schizophrenia patients, six had experienced just one episode of the disorder and the other 77 patients had chronic illness.
All of the participants underwent structural magnetic resonance imaging of the brain.
The researchers found that, overall, schizophrenia patients had reduced global cortical thickness in both hemispheres compared with controls, at 2.48 versus 2.55 mm in the right hemisphere and 2.49 versus 2.54 mm in the left hemisphere.
Schizophrenia patients also had greater regional cortical thinning than controls, particularly in the prefrontal and temporal cortices.
However, the negative correlation between age and cortical thickness showed a similar pattern in patients and controls, both globally and regionally, with highly significant correlations in the frontal and temporal regions.
There was no effect of an interaction between schizophrenia diagnosis and age on cortical thickness, the researchers note in the journal Schizophrenia Research.
Kubota and team conclude: "The present study revealed that schizophrenia was associated with reduced global and regional cortical thickness, and a similar correlation between age and thickness was found in patients with schizophrenia and healthy controls."
They add: "These results suggest that a reduction of cortical thickness in schizophrenia may occur within a relatively early period of the illness, and might reflect pathological processes in a relatively limited period around illness onset rather than progressing over the course of the illness."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Mark Cowen