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25-02-2010 | Mental health | Article

Near-infrared spectroscopy helps identify schizophrenia patients

Abstract

Free abstract

MedWire News: Near-infrared spectroscopy (NIRS) measurements of prefrontal cortex activation could be used to differentiate patients with schizophrenia from healthy individuals, suggests research.

Michiyo Azechi, from Osaka University Graduate School of Medicine in Suita, Japan, and colleagues found that teaming these measurements with performances on certain cognitive tests provided the best classification rate.

“This suggests that combining tools from multiple fields will allow the development of better biologic marker[s], possibly reflecting the pleiotropic or multifaceted aspects of schizophrenia,” they write in the journal Schizophrenia Research.

The researchers divided 60 patients with schizophrenia and 60 mentally healthy controls matched for age and gender each into two sequential groups. They then measured the concentration change in oxygenated hemoglobin in the bilateral prefrontal areas of the participants during the Verbal Fluency Test (VFT) letter version and category version, Tower of Hanoi (TOH), Sternberg’s (SBT), and Stroop Tasks.

In the first group of schizophrenia patients, all showed poorer performance on all the tasks and less prefrontal cortex activation during all but the Stroop Task compared with healthy individuals. In the second group, the schizophrenia patients showed poorer task performance and less cortex activation during VFTs and TOH tasks compared with healthy individuals.

It was not clear why the NIRS measurements appeared to discriminate between schizophrenia patients and healthy controls in the first group but not the second group, but Azechi and team note that there were significantly more outpatients and more patients receiving anxiolytics in the second group.

The researchers then looked at the discrimination accuracy when both task performance and NIRS variables were used as independent variables.

The variables that showed the highest discrimination accuracy were task performance of TOH, VFT letter, and VFT category, and concentration change in oxygenated hemoglobin during the VFT letter task.

Using these independent variables, the researchers were able to correctly classify 88.3% of the participants in the first group as being schizophrenic or mentally healthy, and 75.0% of those in the second group.

“These results suggest that the combination of NIRS measurements and task performances as biologic markers is more desirable for clinical application than NIRS or task performances alone,” say Azechi et al.

They add: “Further studies could utilize simultaneous evaluation of additional disease characteristics including structural and functional brain imaging, physiologic measurements, biochemical examination, neuropsychologic batteries, as well as psychopathology.

“This should provide even clearer diagnostic discrimination by taking into account the varied bio-psycho-social background of each schizophrenia case.

“NIRS represents an excellent physiologic tool in this aim due to its advantages in efficiency, inspection time, and limited invasiveness.”

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 Lucy Piper

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