Plasma Amylin and Cognition in Diabetes in the Absence and the Presence of Insulin Treatment

Abstract

BACKGROUND: Plasma amylin is positively associated with cognitive function in humans. Amylin treatment improves memory in Alzheimer's mouse models. However, the relationship between plasma amylin, diabetes and cognition is not clear.OBJECTIVES: In this study we examined the concentration of plasma amylin, its relationship with diabetes and cognition.MATERIAL AND METHOD: A cross-sectional, homebound elderly population with data of plasma amylin under fasting condition and cognitive measurements was used.RESULTS: We found that subjects with a long and chronic duration of diabetes were more likely to take insulin treatment and have reduced secretion of amylin. Compared to non-diabetics, diabetic subjects without insulin treatment had a higher concentration, but those with insulin treatment had a lower concentration, of plasma amylin [median (Q1, Q3): 20 (11.0, 36.2) vs. 25.2 (13.2, 50.6) vs. 15.0 (4.9, 33.8), p<0.0001]. In the whole sample vs. in the absence of diabetes, plasma amylin was positively associated with logical memory delayed recall (β= +0.61, SE=0.25, p=0.02 vs. β=+0.80, SE=0.33, p=0.02) and block design (β=+0.62, SE=0.24, p=0.009 vs. β=+0.93, SE=0.31, p=0.003), and negatively associated with Trailmaking A scores (β= -6.21, SE=1.55, p<0.0001 vs. β=-7.51, SE=1.95, p=0.0001) and Trailmaking B (β= -4.32, SE=2.13, p=0.04 vs. β= -5.86, SE=2.73, p=0.04). All these relationships disappeared in the presence of diabetes regardless the treatment.CONCLUSION: This study suggests that secretion of amylin by pancreas compensates and then deteriorates depending on the duration of diabetes. Amylin's activities for cognition are impaired in the presence of diabetes.