• Ken-Ichiro Yamashita, Yoshihide Taniwaki, Hidetsuna Utsunomiya, and Takayuki Taniwaki.
• Division of Respirology, Neurology and Rheumatology, Department of Medicine, Kurume University School of Medicine, Fukuoka, Japan.
• J Neuroimaging. 2014 Nov 1;24(6):590-4.

Background And PurposeImpairment of orientation for time (OT) is a characteristic symptom of Alzheimer disease (AD). However, the brain regions underlying OT remain to be elucidated. Using single photon emission computed tomography (SPECT), we examined the brain regions exhibiting hypoperfusion that were associated with OT.MethodsWe compared regional cerebral blood flow (rCBF) differences between AD and amnesic mild cognitive impairment (aMCI) or normal subjects using 3-dimensional stereotactic surface projection (3D-SSP) analysis. AD patients were divided into OT good and poor groups according to their mean OT scores, and rCBF then compared between the groups to elucidate OT-specific brain areas.Results3D-SSP analysis showed reduced rCBF in the left superior parietal lobule (SPL) and bilateral inferior parietal lobule (IPL) in AD patients. In the poor OT group, 3D-SSP analysis revealed hypoperfusion in the bilateral SPL, IPL, posterior cingulated cortex (PCC), and precuneus. Among these areas, region of interest analysis revealed a significant higher number of hypoperfused pixels in the left PCC in the OT poor AD group.ConclusionsOur SPECT study suggested that hypoperfusion in the left SPL and bilateral IPL was AD specific, and reduced rCBF in the left PCC was specifically associated with OT.Copyright © 2014 by the American Society of Neuroimaging.

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