Dietary influences on cognition

Abstract

Obesity is a world-wide crisis with profound healthcare and socio-economic implications and it is now clear that the central nervous system (CNS) is a target for the complications of metabolic disorders like obesity. In addition to decreases in physical activity and sedentary lifestyles, diet is proposed to be an important contributor to the etiology and progression of obesity. Unfortunately, there are gaps in our knowledge base related to how dietary choices impact the structural and functional integrity of the CNS. For example, while chronic consumption of hypercaloric diets (increased sugars and fat) contribute to increases in body weight and adiposity characteristic of metabolic disorders, the mechanistic basis for neurocognitive deficits in obesity remains to be determined. In addition, studies indicate that acute consumption of hypercaloric diets impairs performance in a wide variety of cognitive domains, even in normal non-obese control subjects. These results from the clinical and basic science literature indicate that diet can have rapid, as well as long lasting effects on cognitive function. This review summarizes our symposium at the 2017 Society for the Study of Ingestive Behavior (SSIB) meeting that discussed these effects of diet on cognition. Collectively, this review highlights the need for integrated and comprehensive approaches to more fully determine how diet impacts behavior and cognition under physiological conditions and in metabolic disorders like type 2 diabetes mellitus (T2DM) and obesity.

Keywords: Dementia; Diabetes; Fructose; Impassivity; Insulin; Obesity.

Figure 1

A) Schematic of the TUNL task showing the location of a sample stimulus, followed by the sample and target on an array with either a large or small separation. B) Preliminary data showing TUNL performance (% correct) in control and high sucrose diet rats [N=8 / group, One way ANOVA with between subjects factor of diet (control, sucrose). Large separation (F(1,14) = 0.043, P = 0.84; small separation (F(1,14) = 7.34, P = 0.02). * = P<0.05].

Figure 2

A) Schematic representation of the SLR task and spatial arrangement of the objects in the d-SLR and s-SLR component. B) Performance of control and high sucrose diet rats during the d-SLR and s-SLR tasks. Discrimination ratio = (Time novel – Time familiar) / (novel + familiar) (Time novel + Time familiar). N’s = 6 per group. *** = P<0.001. Adapted (with permission) from Reichelt, A.C., Morris, M.J., Westbrook, R.F., 2016. Daily access to sucrose impairs aspects of spatial memory tasks reliant on pattern separation and neural proliferation in rats. Learning & memory 23, 386–390.