Open AccessEntorhinal cortex and parahippocampus volume reductions impact olfactory decline in aged subjects
Author(s) -
Iizuka Natsuko,
Masaoka Yuri,
Kubota Satomi,
Sugiyama Haruko,
Yoshida Masaki,
Yoshikawa Akira,
Koiwa Nobuyoshi,
Honma Motoyasu,
Watanabe Keiko,
Kamijo Shotaro,
Kamimura Sawa,
Ida Masahiro,
Ono Kenjiro,
Izumizaki Masahiko
Publication year - 2021
Publication title -
brain and behavior
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 41
ISSN - 2162-3279
DOI - 10.1002/brb3.2115
Subject(s) - entorhinal cortex , hippocampus , dentate gyrus , neuroscience , temporal cortex , medicine , olfaction , cognitive decline , orbitofrontal cortex , lingual gyrus , olfactory system , brain size , dementia , psychology , functional magnetic resonance imaging , magnetic resonance imaging , cognition , pathology , prefrontal cortex , disease , radiology
Pathological abnormalities first appear in the medial temporal regions including entorhinal cortex and parahippocampus in patients with Alzheimer's disease. Previous studies showed that olfactory decline in elderly subjects was associated with volume reductions in the left hippocampus and left parahippocampus without cognitive impairment. The aim of this study is to investigate the link between olfaction and volume reductions in the medial temporal regions including the parahippocampus, entorhinal cortex, and hippocampal subfields. Method 27 elderly subjects and 27 young controls were measured olfaction acuity, cognitive function, and structural magnetic resonance imaging. Image processing and gray matter volumetric segmentation were performed with FreeSurfer. Volume data were analyzed with SPSS Statistics software. Results Interesting results of this study were that volume reduction in the entorhinal cortex was not directly linked with declining olfactory ability. Volume reduction in the left entorhinal cortex was correlated with volume reduction in the left parahippocampus and dentate gyrus. However, left parahippocampus volume reduction had the greatest impact on olfactory decline, and the entorhinal cortex and dentate gyrus might additionally contribute to olfactory decline. Conclusion Our results indicate that olfactory decline may be directly reflected in the medial temporal regions as reduced parahippocampus volumes, rather than as morphological changes in the entorhinal cortex and hippocampus. The parahippocampus may play an important role in the association between memory retrieval and olfactory identification.