Summary: A University of Warwick study reports that modestly raising blood sugar can boost memory, mood, and motivation in adults over 60.
Source: University of Warwick
Glucose boosts memory and motivation in older adults, new study finds
Researchers at the University of Warwick report that a small increase in blood glucose can enhance memory performance and increase motivation in older adults. The study, led by PhD student Konstantinos Mantantzis with Professor Elizabeth Maylor and Dr. Friederike Schlaghecken from Warwick’s Department of Psychology, compared the effects of a glucose drink with a placebo sweetened with artificial sweetener on both young and older participants.
Participants were divided into two age groups: younger adults (18–27 years) and older adults (65–82 years). Each participant consumed either a drink containing a modest amount of glucose or a matched placebo drink containing artificial sweetener, then completed a series of memory-search tasks that varied in difficulty. The researchers recorded objective indicators of cognitive engagement, including changes in heart rate, alongside measures of memory accuracy, subjective effort, and mood.
The findings show that consuming glucose increased task engagement in both age groups, as reflected by higher heart rate responses during the tasks compared with placebo. However, the cognitive and emotional benefits differed by age. In younger adults, glucose increased physiological engagement but did not lead to measurable improvements in memory performance or mood. In contrast, older adults who received glucose not only showed greater physiological engagement but also demonstrated significant improvements in memory performance and reported more positive mood.
Interestingly, although objective measures indicated that older adults in the glucose group exerted more effort, their self-reports did not reflect an increased sense of effort. In other words, older participants put in more cognitive effort after taking glucose without feeling that the task had become harder. This dissociation between objective engagement and subjective effort suggests that glucose may reduce the perceived cost of exertion while enabling higher performance in demanding tasks.
The authors suggest that short-term energy availability—provided by glucose—may play an important role in motivating older adults to perform at their best. Enhanced motivation could also explain related benefits observed in the study: improved self-confidence, lower perceived effort, and better mood among older participants after glucose consumption.
While the results are promising, the researchers caution against overgeneralizing. More research is needed to fully understand the mechanisms linking energy availability with cognitive engagement and affect in older age. Future work will be important for teasing apart motivational, physiological, and affective components and for developing evidence-based dietary recommendations for older adults.
Konstantinos Mantantzis, PhD student at the University of Warwick’s Department of Psychology, commented:
“Engaging actively with difficult cognitive tasks helps maintain cognitive health as we age. Understanding what encourages older adults to invest effort in challenging tasks is therefore crucial.”
Dr. Friederike Schlaghecken, Department of Psychology, added:
“These findings bring us closer to identifying factors that increase older adults’ willingness to exert effort, even when tasks seem demanding or daunting.”
This research was conducted by Konstantinos Mantantzis, Professor Elizabeth Maylor, and Dr. Friederike Schlaghecken at the University of Warwick, UK. The study examined whether raising blood glucose could increase cognitive engagement and protect positive affect in older adults during demanding tasks.
Publisher: NeuroscienceNews.com (organized coverage)
Original research: Mantantzis, Konstantinos; Maylor, Elizabeth A.; Schlaghecken, Friederike. “Gain without pain: Glucose promotes cognitive engagement and protects positive affect in older adults.” Psychology and Aging. Published July 12, 2018. doi: 10.1037/pag0000270
Gain without pain: Glucose promotes cognitive engagement and protects positive affect in older adults
This study investigated whether a modest glucose boost helps older adults invest more effort in demanding cognitive tasks and whether such increased engagement is accompanied by preserved or enhanced positive affect. Fifty-three younger adults and 58 older adults consumed either a glucose drink or a placebo and completed a memory-search task at three difficulty levels. Cognitive engagement was assessed by heart rate changes and self-reported effort, and affect was evaluated via an implicit emotion-assessment task after each block. Glucose increased physiological markers of engagement in both age groups. Critically, in older adults—but not in younger adults—glucose led to measurable improvements in memory performance and to more positive affect, while subjective reports of effort did not increase. These results indicate that in older adults, glucose can enhance cognitive performance by promoting greater engagement while reducing the perceived cost of exertion.
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