Full Papers

Lifestyle, glucose regulation and the cognitive effects of glucose load in middle-aged adults

Leigh M. Riby^a1 c1, Jennifer McLaughlin^a2 and Deborah M. Riby^a3

^a1 Division of Psychology, Northumbria University, Northumberland Building, Newcastle upon Tyne NE1 8ST, UK

^a2 Department of Psychology, Glasgow Caledonian University, UK

^a3 Department of Psychology, Newcastle University, UK

Abstract

Interventions aimed at improving glucose regulatory mechanisms have been suggested as a possible source of cognitive enhancement in the elderly. In particular, previous research has identified episodic memory as a target for facilitation after either moderate increases in glycaemia (after a glucose drink) or after improvements in glucose regulation. The present study aimed to extend this research by examining the joint effects of glucose ingestion and glucose regulation on cognition. In addition, risk factors associated with the development of poor glucose regulation in middle-aged adults were considered. In a repeated measures design, thirty-three middle-aged adults (aged 35–55 years) performed a battery of memory and non-memory tasks after either 25 g or 50 g glucose or a sweetness matched placebo drink. To assess the impact of individual differences in glucose regulation, blood glucose measurements were taken on four occasions during testing. A lifestyle and diet questionnaire was also administered. Consistent with previous research, episodic memory ability benefited from glucose ingestion when task demands were high. Blood glucose concentration was also found to predict performance across a number of cognitive domains. Interestingly, the risk factors associated with poor glucose regulation were linked to dietary impacts traditionally associated with poor health, e.g. the consumption of high-sugar sweets and drinks. The research replicates earlier work suggesting that task demands are critical to the glucose facilitation effect. Importantly, the data demonstrate clear associations between elevated glycaemia and relatively poor cognitive performance, which may be partly due to the effect of dietary and lifestyle factors.

(Received May 14 2007)

(Revised February 28 2008)

(Accepted February 28 2008)

(Online publication April 01 2008)

Key Words:

• Lifestyle;
• Diet;
• Glucose;
• Glucose regulation;
• Cognition;
• Memory

Correspondence:

^c1 Corresponding author: Dr Leigh Martin Riby, fax +44 191 227 4515, email leigh.riby@unn.ac.uk

Footnotes

Abbreviations: GRI, glucose regulation index; MSE, mean squared error