Reduced prefrontal cortex activation using the Trail Making Test in schizophrenia

Ryo Fujiki,1,2 Kiichiro Morita,1,2 Mamoru Sato,1,2 Yuji Kamada,1,2 Yusuke Kato,1,2 Masayuki Inoue,2 Yoshihisa Shoji,1,2 Naohisa Uchimura1 1Department of Neuropsychiatry, Kurume University School of Medicine, Kurume-City, Japan; 2Cognitive and Molecular Research Institute of Brain Diseases, Kurume University School of Medicine, Kurume-City, Japan Abstract: Schizophrenia has been associated with a deficit of the prefrontal cortex, which is involved in attention, executive processes, and working memory. The Trail Making Test (TMT) is administered in two parts, TMT-A and TMT-B. It is suggested that the difference in performance between part A and part B reflects executive processes. In this study, we compared the characteristics of hemodynamic changes during TMT tasks between 14 outpatients with schizophrenia and 14 age- and gender-matched healthy control subjects. Using multichannel near-infrared spectroscopy, we measured relative changes in oxygenated hemoglobin concentration, which reflects brain activity of the prefrontal cortex during this task. In both tasks, patients showed significantly smaller activation than controls and, in an assessment of executive functions, a subtraction of oxygenated hemoglobin (oxy-Hb) changes during TMT-A from those of TMT-B showed a decrease in cerebral lateralization and hypoactivity in patients. There was a significant negative correlation between oxy-Hb changes and the severity of psychiatric symptoms. These findings may characterize disease-related features, suggesting the usefulness of oxy-Hb change measurement during TMT tasks for assessing functional outcomes in schizophrenic patients. Keywords: Trail Making Test, multichannel near-infrared spectroscopy, schizophrenia, prefrontal cortex, executive function