Increased Glucose Levels Are Associated With Episodic Memory in Nondiabetic Women

Abstract

Patients with type 2 diabetes have an increased risk of a reduction in cognitive function. We investigated the hypothesis that plasma glucose is associated with a reduction in episodic and/or semantic memory already in nondiabetic subjects. We linked two large population-based datasets in Sweden: the Betula study, in which a random sample from the population aged 35-85 years was investigated for cognitive function, including episodic and semantic memory; and the Västerbotten Intervention Program, a health survey with subjects aged 40, 50, and 60 years, that includes measuring of fasting and 2-h plasma glucose, along with other risk factors for diabetes and cardiovascular disease. We identified 411 (179 men and 232 women, mean age 50.6 +/- 8.0 years) nondiabetic subjects, free from dementia, who had participated in the two surveys within 6 months. Women had better episodic (score 7.37 +/- 1.42) and semantic memory (score 16.05 +/- 2.76) than men (score 6.59 +/- 1.29 and 15.15 +/- 2.92, respectively, P < 0.001 for both). In an adjusted multivariate model, fasting plasma glucose (fPG) and 2-h plasma glucose (2hPG) were significantly negatively associated with episodic memory (fPG: B -0.198, SE 0.068, beta -0.209, P = 0.004; and 2hPG: B -0.061, SE 0.031, beta -0.148, P = 0.048, respectively) in women but not in men. The association was not found in relation to semantic memory. We conclude that an increase in plasma glucose is associated with impairment in episodic memory in women. This could be explained by a negative effect on the hippocampus caused by raised plasma glucose levels.