title: Serum 25-hydroxyvitamin D is associated with reduced verbal episodic memory in healthy, middle-aged and older adults.
abstract: BACKGROUND
  There is increasing evidence supporting an association of higher serum vitamin D concentration with better cognitive performance in older individuals. However, to date, consideration of the putative association between vitamin D and cognition has been based principally on studies investigating clinical participant samples manifesting vitamin D deficiency, particularly in older people. Moreover, relationships between vitamin D and cognition are typically not considered in the context of counter-regulatory calcium-modulating hormones or calcium homeostasis.
  
  
  OBJECTIVE
  Serum vitamin D/bioactive (ionised) calcium/parathyroid hormone homeostasis was considered in the context of cognitive performance in healthy, middle-aged and older individuals.
  
  
  METHODS
  A cross-sectional sample of 179 participants between the ages of 47-84 years was recruited for this study (114 females, 65 males). Participants provided fasting blood samples for analysis of serum 25-hydroxyvitamin D levels, ionised calcium (iCa) and parathyroid hormone (PTH) and completed cognitive measures of verbal episodic learning and memory.
  
  
  RESULTS
  Serum 25-hydroxyvitamin D concentrations were negatively associated (with and without covariates of age, gender, depression and NART scores, iCa, and PTH) with measures of verbal episodic learning and memory, in particular with trial 5 of the Rey Auditory Verbal Learning Test (RAVLT) and long-delay free recall on the RAVLT.
  
  
  CONCLUSIONS
  Overall, the findings from this study suggest an association between higher vitamin D status and poorer performance on verbal episodic memory in middle-aged and older individuals with normal vitamin D-calcium-PTH homeostasis. Despite requiring replication in other participant samples, this is a potentially important finding as it indicates that it may not be beneficial from a cognitive perspective to provide vitamin D supplements in individuals with already adequate vitamin D status.
authors.affiliation: School of Public Health, Curtin University, Perth, WA, Australia.|Curtin Health Innovation Research Institute - Biosciences, Curtin University, Perth, WA, Australia.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lam
authors.affiliation: School of Public Health, Curtin University, Perth, WA, Australia.|Curtin Health Innovation Research Institute - Biosciences, Curtin University, Perth, WA, Australia.|Maryland Psychiatric Research Center, Department of Psychiatry, School of Medicine, University of Maryland, Baltimore, MD, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Albrecht
authors.affiliation: School of Public Health, Curtin University, Perth, WA, Australia.|Curtin Health Innovation Research Institute - Biosciences, Curtin University, Perth, WA, Australia.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Takechi
authors.affiliation: School of Pharmacy, Perth, WA, Australia.
authors.forename: Prachya
authors.initials: P
authors.lastname: Prasopsang
authors.affiliation: School of Pharmacy, Perth, WA, Australia.
authors.forename: Ya Ping
authors.initials: YP
authors.lastname: Lee
authors.affiliation: School of Psychology and Speech Pathology, Curtin University, Perth, WA, Australia.|Neurosciences Unit, Health Department of Western Australia, Perth, WA, Australia.
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Foster
authors.affiliation: School of Public Health, Curtin University, Perth, WA, Australia. J.Mamo@Curtin.edu.au.|Curtin Health Innovation Research Institute - Biosciences, Curtin University, Perth, WA, Australia. J.Mamo@Curtin.edu.au.
authors.forename: John C L
authors.initials: JC
authors.lastname: Mamo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D003071:Cognition / Q000187:drug effects; D003430:Cross-Sectional Studies; D005215:Fasting; D005260:Female; D006801:Humans; D007858:Learning / Q000187:drug effects; D016014:Linear Models; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium
keywords: Cognition; Ionised calcium; Parathyroid hormone; Serum 25-hydroxyvitamin D; Verbal episodic memory; Vitamin D