Glucose effects on long-term memory performance: duration and domain specificity.
BACKGROUND
Previous research has suggested that long-term verbal declarative memory is particularly sensitive to enhancement by glucose loading; however, investigation of glucose effects on certain memory domains has hitherto been neglected. Therefore, domain specificity of glucose effects merits further elucidation.


OBJECTIVE
The aim of the present research was to provide a more comprehensive investigation of the possible effects of glucose administration on different aspects of memory by 1) contrasting the effect of glucose administration on different memory domains (implicit/explicit memory; verbal/non-verbal memory, and recognition/familiarity processes), 2) investigating whether potential effects on memory domains differ depending on the dose of glucose administered (25 g versus 60 g), 3) exploring the duration of the glucose facilitation effect (assessment of memory performance 35 min and 1 week after encoding).


METHODS
A double-blind between-subjects design was used to test the effects of administration of 25 and 60 g glucose on memory performance.


RESULTS
Implicit memory was improved following administration of 60 g of glucose. Glucose supplementation failed to improve face recognition performance but significantly improved performance of word recall and recognition following administration of 60 g of glucose. However, effects were not maintained 1 week following encoding.


CONCLUSIONS
Improved implicit memory performance following glucose administration has not been reported before. Furthermore, the current data tentatively suggest that level of processing may determine the required glucose dosage to demonstrate memory improvement and that higher dosages may be able to exert effects on memory pertaining to both hippocampal and non-hippocampal brain regions.
NICM Centre for the Study of Natural Medicines and Neurocognition, Brain Sciences Institute, Melbourne, VIC, 3122, Australia. lauren.j.owen@gmail.com
Lauren
L
Owen
Yvonne
Y
Finnegan
Henglong
H
Hu
Andrew B
AB
Scholey
Sandra I
SI
Sünram-Lea
D000293:Adolescent; D000328:Adult; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects*; D021641:Recognition, Psychology / Q000187:drug effects; D013997:Time Factors; D055815:Young Adult
D005947:Glucose