Glucose regulation is associated with attentional control performances in nondiabetic older adults

Abstract

Less efficient glucose regulation, the ability to metabolize glucose, has been associated with poorer cognitive performances in older individuals not meeting criteria for type 2 diabetes (Messier, Tsiakas, Gagnon, & Desrochers, 2010). Yet, the influence of glucose regulation on attentional functions, which are sensitive to aging, is still unclear. The present study examined the relationship between glucose regulation and performances on attentional tasks in nondiabetic older adults. Twenty-two participants (60 years and older) were tested on neuropsychological tests of attention (Trail Making test, modified Stroop test) and on a computerized dual task, after receiving a 50-g glucose drink. Participants with the worse glucose regulation committed more errors on the switching condition of the modified Stroop test (p < .05) and tended to make more errors in divided-attention trials of the computerized dual task (p = .05). Altogether, these results suggest that glucose regulation may transiently influence performances of metabolically healthy older adults on tasks requiring switching attention.

Keywords:

• Glucose regulation
• Aging
• Attentional control

Acknowledgments

This research was supported by a scientist fellowship from the Fonds de Recherche en Santé du Québec to L.B and by a Canadian Institutes of Health Research (CIHR) fellowship to C.G.

Notes

¹Examination of reaction time (RT) differences between dual–mixed trials and single–mixed trials confirmed that most participants prioritized one task over another. Using the same dual-task paradigm, Schumacher and colleagues (2001) defined perfect time sharing between two concurrent tasks as a difference in RTs between single-task trials performed in the mixed block and dual-task trials smaller than 100 ms, after substantial practice. We adjusted the criterion to a 150-ms value because our participants were older adults and had not been previously trained on the tasks. This criterion was reached by 13 participants. For the others, determination of the prioritized task was based on the smallest difference between dual–mixed and single–mixed trials. On the prioritized task, mean RTs for dual–mixed trials (M = 1,285 ms) nearly reached the values of mean RTs on single–mixed trials (M = 1,211 ms). On the nonprioritized task, the mean RT for dual–mixed trials (M = 1,750 ms) was much larger than the mean RT for single–mixed trials (M = 1,285 ms).