Mapping hypofrontality during letter fluency task in schizophrenia: A multi-channel near-infrared spectroscopy study

• Published in: Schizophrenia research Vol. 136; no. 1; pp. 63 - 69
• Main Authors: Shimodera, Shinji, Imai, Yutaka, Kamimura, Naoto, Morokuma, Ippei, Fujita, Hirokazu, Inoue, Shimpei, Furukawa, Toshi A
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2012; Elsevier
• Subjects: Adolescent; Adult; Adult and adolescent clinical studies; Aged; Aged, 80 and over; Area Under Curve; Biological and medical sciences; Brain Mapping; Cognition Disorders - diagnosis; Cognition Disorders - etiology; Female; Humans; Hypofrontality; Image Processing, Computer-Assisted; Letter fluency test; Male; Medical sciences; Middle Aged; Near-infrared spectroscopy; Neuropsychological Tests; Oxyhemoglobins - metabolism; Prefrontal Cortex - pathology; Psychiatric Status Rating Scales; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychoses; Schizophrenia; Schizophrenia - complications; Schizophrenia - diagnosis; Spectroscopy, Near-Infrared - methods; Statistics as Topic; Time Factors; Verbal Behavior - physiology; Young Adult; Schizophrenia; Hypofrontality; Letter fluency test; Near-infrared spectroscopy; Psychosis; Human; Cartography; Near infrared spectrometry; Verbal fluency; Language
• ISSN: 0920-9964; 1573-2509
• DOI: 10.1016/j.schres.2012.01.039

Abstract Cognitive impairment and associated frontal lobe dysfunction characterize schizophrenia. The letter fluency test (LFT) has been used as one of the most sensitive measures of the cognitive dysfunction, but the nature and topography of the hypofrontality have yet to be fully elucidated. In this study we used multi-channel near-infrared spectroscopy (NIRS), a recently developed noninvasive functional imaging technique, to measure changes in the concentration of oxygenated hemoglobin in the prefrontal cortices of 31 schizophrenia patients and 26 age- and sex-matched healthy controls during performance of the LFT. The results demonstrated reduced prefrontal cortex activation during the LFT among the schizophrenia patients in comparison with the healthy controls, even after controlling for medication. The hypofrontality was most salient in the prefrontal ventrolateral subregion bilaterally. The reduced activity appeared to be due not only to the lesser magnitude but also to the lesser fluctuation of the changes in oxygenated hemoglobin concentration. The hypofrontality appeared to be independent of the patients' symptomatological manifestations. We concluded that measuring NIRS during performance of the LFT can detect prefrontal lobe dysfunction of schizophrenia patients and may provide a new tool to monitor their treatment and course.