title: Age-related changes in prefrontal oxygenation during memory encoding and retrieval.
abstract: OBJECTIVE
  Memory dysfunction is a major component of age-related cognitive decline, and is a marker of cognitive impairment. Emerging evidence suggests that the prefrontal cortex is required for maintenance of memory functions. The purpose of the present study was to elucidate age-related changes in prefrontal oxygenation during memory encoding and retrieval using near-infrared spectroscopy.
  
  
  METHODS
  We examined 21 young (mean age 24.3 years), 52 young-old (mean age 69.7 years) and 50 old-old (mean age 79.5 years) participants. The concentration of oxyhemoglobin, which is a reliable biomarker of changes in regional cerebral blood flow, in the right and left prefrontal cortex was measured during encoding and delayed retrieval of a list of 10 target words. The average number of correct answers in the retrieval task was used as a measure of task performance.
  
  
  RESULTS
  During encoding, oxyhemoglobin was significantly and bilaterally lower in young-old and old-old participants compared with young participants. Meanwhile, during retrieval, only old-old participants showed significantly decreased oxyhemoglobin compared with young and young-old participants. The old-old participants showed fewer correct answers in the retrieval period than the young and young-old participants.
  
  
  CONCLUSIONS
  Old-old participants showed reduced prefrontal oxygenation during both encoding and retrieval, and decreased memory performance compared with younger participants. It is necessary for the clinical application of near-infrared spectroscopy to consider the effects of demographic variables on cerebral oxygenation. Geriatr Gerontol Int 2016; 16: 1296-1304.
authors.affiliation: Institute of Innovation for Future Society, Nagoya University, Nagoya, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Uemura
authors.affiliation: Department of Preventive Gerontology, Center for Gerontology and Social Science, Obu, Japan.|Japan Society for the Promotion of Science, Tokyo, Japan.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Doi
authors.affiliation: Department of Preventive Gerontology, Center for Gerontology and Social Science, Obu, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimada
authors.affiliation: Department of Preventive Gerontology, Center for Gerontology and Social Science, Obu, Japan.
authors.forename: Hyuma
authors.initials: H
authors.lastname: Makizako
authors.affiliation: Department of Medicinal Biotechnology, Dong-A University, Busan, Korea.
authors.forename: Hyuntae
authors.initials: H
authors.lastname: Park
authors.affiliation: National Center for Geriatrics and Gerontology, Obu, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D060825:Cognitive Dysfunction; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D010100:Oxygen / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: aging; brain; cognitive decline; dementia; memory; near-infrared spectroscopy