Comparison of changes in oxygenated hemoglobin during the tree-drawing task between patients with schizophrenia and healthy controls
Received 15 December 2017
Accepted for publication 19 February 2018
Published 20 April 2018 Volume 2018:14 Pages 1071—1082
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 2
Editor who approved publication: Dr Taro Kishi
Shinya Nakano,1,2 Yoshihisa Shoji,1,3 Kiichiro Morita,1,3 Hiroyasu Igimi,1,4 Mamoru Sato,1,3 Youhei Ishii,1 Akihiko Kondo,1 Naohisa Uchimura1,3
1Cognitive and Molecular Research Institute of Brain Diseases, Kurume University, Kurume, Japan; 2Department of Clinical Laboratory Medicine, Kurume University Hospital, Kurume, Japan; 3Department of Neuropsychiatry, Kurume University School of Medicine, Kurume, Japan; 4Department of Neuropsychiatry, Horikawa Hospital, Medical Corporation Association Horikawakai, Kurume, Japan
Background: Tree-drawing test is used as a projective psychological test that expresses the abnormal internal experience in patients with schizophrenia (SZ). Despite the widely accepted view that the cognitive function is involved in characteristic tree-drawing in patients with SZ, no study has psychophysiologically examined it. The present study aimed to investigate the involvement of cognitive function during tree-drawing in patients with SZ. For that purpose, we evaluated the brain function in patients with SZ during a tree-drawing task by using near-infrared spectroscopy (NIRS) and compared them with those in healthy controls.
Patients and methods: The subjects were 28 healthy controls and 28 patients with SZ. Changes in the oxygenated hemoglobin ([oxy-Hb]) concentration in both the groups during the task of drawing a tree imagined freely (free-drawing task) and the task of copying an illustration of a tree (copying task) were measured by using NIRS.
Results: Because of the difference between the task conditions, [oxy-Hb] levels in controls during the free-drawing task were higher than that during the copying task at the bilateral frontal pole regions and left inferior frontal region. Because of the difference between the groups, [oxy-Hb] levels at the left middle frontal region, bilateral inferior frontal regions, bilateral inferior parietal regions, and left superior temporal region during the free-drawing task in patients were lower than that in controls.
Conclusion: [oxy-Hb] during the tree-drawing task in patients with SZ was lower than that in healthy controls. Our results suggest that brain dysfunction in patients with SZ might be associated with their tree-drawing.
Keywords: tree-drawing test, near-infrared spectroscopy, cognitive function, mnemonic retrieval, executive function, working memory, attention
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