Glucose administration prior to a divided attention task improves tracking performance but not word recognition: evidence against differential memory enhancement?
BACKGROUND
The cognition-enhancing effects of glucose administration to humans have been well-documented; however, it remains unclear whether this effect preferentially targets episodic memory or other cognitive domains.


OBJECTIVE
The effect of glucose on the allocation of attentional resources during memory encoding was assessed using a sensitive dual-attention paradigm.


METHODS
One hundred and twenty volunteers (mean age 21.60, SD 4.89, 77 females) took part in this randomised, double-blind, placebo-controlled, parallel groups study where each consumed a 25-g glucose drink or a placebo. Half of the participants in each drink condition attempted to track a moving on-screen target during auditory word presentation. The distance between the cursor and the tracking target was used as an index of attentional cost during encoding. Effects of drink and tracking on recognition memory and drink on tracking performance were assessed. Self-rated appetite and mood were co-monitored.


RESULTS
Co-performing the tracking task significantly impaired memory performance irrespective of drink condition. In the placebo-tracking condition, there was a cost to tracking manifest as greater deviation from target during and immediately following word presentation. Compared with placebo, the glucose drink significantly improved tracking performance during encoding. There were significant time-related changes in thirst and alertness ratings but these were not differentially affected by drink or tracking conditions.


CONCLUSIONS
Tracking but not memory was enhanced by glucose. This finding suggests that, under certain task conditions, glucose administrations does not preferentially enhance memory performance. One mechanism through which glucose acts as a cognition enhancer is through allowing greater allocation of attentional resources.
Scholey
Andrew B
AB
NICM Centre for Study of Natural Medicines and Neurocognition, Brain Sciences Institute, Swinburne University, Melbourne, VIC 3122, Australia. andrew@scholeylab.com
Sünram-Lea
Sandra I
SI
Greer
Joanna
J
Elliott
Jade
J
Kennedy
David O
DO
D000339:Affect / Q000187:drug effects; D001066:Appetite / Q000187:drug effects; D001288:Attention / Q000187:drug effects*; D001786:Blood Glucose / Q000378:metabolism; D004311:Double-Blind Method; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D006815:Hunger / Q000187:drug effects; D008297:Male; D008568:Memory / Q000187:drug effects*; D011597:Psychomotor Performance / Q000187:drug effects*; D011932:Reading; D021641:Recognition, Psychology / Q000187:drug effects*; D013894:Thirst / Q000187:drug effects; D055815:Young Adult
D001786:Blood Glucose; D005947:Glucose