Hippocampus & BDNF & Synaptic Plasticity & Calorie Intake Baste on 31 Jul 2008 05:04 am
Western High Calorie Diets Impair Cognition and Hippocampal Synaptic Plasticity
Source: Hippocampus, 23 July 2008
Article Type: Original Research
Authors: Stranahan AM et al.
Learning and memory crucially depend on the integrity of the hippocampus which is located in the medial temporal lobe. The hippocampus is often considered as a “gateway” through which new memories must pass before entering permanent storage in the brain. Various authors suggested that high calorie diets might negatively affect the hippocampus and thus learning and memory.
The team of Mark P. Matson from the Laboratory of Neuroscience (National Institute of Aging) now provides further insight of how a Western-like diet high in energy (high-fat, high-glucose food supplemented with 20% high-fructose corn syrup in the drinking water) impairs cognitive function. In comparison to control rats fed a standard diet, middle-aged rats maintained on the high calorie diet exhibited marked physiological and biochemical changes in the brain:
“We observed impaired learning and LTP [long-term potentiation], as well as reduced dendritic spine density in response to excessive caloric intake. Impairment of dendritic spine density and synaptic plasticity was accompanied by reductions in hippocampal BDNF [a neurothrophic factor] levels. Excessive caloric intake also increased fasting blood glucose levels and elevated serum lipids. Because alterations in hippocampal plasticity occurred in the context of a serum profile resembling diabetes, we conclude that the endocrine perturbations induced by excessive caloric intake may be detrimental for hippocampal structure and function. (…)
Diets high in refined sugars and saturated fats increase the risk of type 2 diabetes and individuals with poorly controlled diabetes frequently exhibit impaired cognitive function. (…)
Deficits in hippocampal function may arise from peripheral insulin resistance and hyperlipidemia induced by a high calorie diet. An alternative hypothesis would suggest that differences in the balance of proteins, carbohydrates, and fats between the two diets might have a direct effect on hippocampal plasticity, independently of peripheral metabolic alterations. In support of this idea, direct injection of triglycerides into the brain has detrimental consequences for learning and memory, whereas focal application of glucose enhances cognition. The extent to which different dietary components exert direct effects on central neuroplasticity remains to be determined.”
If you like to learn more about Marc Mattson’s work I strongly recommend you have a look at a profile report on him, published in volume 10 of Nature Medicine (2004).