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14-09-2011 | Psychology | Article

Schizophrenia patients show excessive cortical thinning over time


Free abstract

MedWire News: Patients with schizophrenia demonstrate excessive thinning of the cortex over time relative to mentally healthy individuals, study results show.

Writing in the Archives of General Psychiatry, Neeltje van Haren (University Medical Center Utrecht, The Netherlands) and team explain: "Evidence is accumulating that schizophrenia is characterized by excessive loss of cerebral gray matter (GM) volume over time in the early and chronic stages of the disease. Because most GM tissue is found in the cortex, excessive cortical thinning may explain part of the excessive decreases in GM volume reported in this disease."

However, they add that "unlike changes in global GM in schizophrenia over time, cortical thickness has not been studied longitudinally."

To address this, the researchers studied 96 patients with schizophrenia and 113 mentally healthy individuals (controls) who were aged between 16 and 56 years.

Magnetic resonance imaging was used to assess cortical thickness at baseline and after 5 years of follow up.

At baseline, the researchers note that there was no significant difference in mean cortical thickness between patients and controls. However, patients had a significantly thinner cortex in the left orbitofrontal and right superior temporal cortex, and parahippocampal gyrus compared with controls, and increased thickness in the superior parietal lobule and occipital pole.

In controls, mean cortical thinning was minimal after 5 years, at just -0.01 mm. Indeed, 57% of controls showed a decrease in mean cortical thickness, whereas the remaining 43% showed an increase after 5 years.

In the schizophrenia patients, however, the decrease in mean cortical thickness after 5 years was significantly more pronounced, at -0.05 mm, with 75% showing a decrease in mean thickness, with no increase in mean cortical thickness among the remaining patients.

Cortical thinning over time in the schizophrenia patients was widespread, and most pronounced bilaterally in the temporal cortex and in the left frontal area.

The researchers also found that poor outcomes were associated with greater cortical thinning, as was a higher cumulative intake of typical antipsychotics. A higher cumulative intake of atypical antipsychotics was associated with less-pronounced cortical thinning.

Van Haren and team conclude: "We found compelling evidence of excessive and progressive thinning of the cortex over time in patients with schizophrenia in widespread areas of the cortical mantle, with the largest loss of cortical thickness in frontal and temporal areas of the brain."

They add that the findings also indicate that "excessive thinning of the cortex over time in schizophrenia is related to disease-related factors."

By Mark Cowen

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