We found that chronic consumption of sugar in rats who were not stressed produced similar changes in the hippocampus as seen in the rats who were stressed but not drinking sugar. Early life stress exposure or sugar drinking led to lower expression of the receptor that binds the major stress hormone cortisol, which may affect the ability to recover from exposure to a stressful situation.
Another gene that is important for the growth of nerves, Neurod1, was also reduced by both sugar and stress. Other genes important for the growth of nerves were investigated, and just drinking sugar from a young age was sufficient to reduce them.
The rats were exposed to high sugar intakes during development, and the impact of the sugar is worrying as it may affect brain development, although further work is required to test this.
In this study, combining sugar intake and early life stress did not produce further changes in the hippocampus, but whether this remains the case over time is unclear.
What does this mean for us?
The changes in the brain induced by sugar are of great concern given the high consumption of sugar-sweetened beverages, with particularly high consumption in children aged nine to 16 years. If similar processes are at play in humans to what was found in our rat study, reducing the consumption of sugar across the community is important.
The fact that drinking sugar or exposure to early life stress reduced the expression of genes critical for brain development and growth is of great concern. While it is impossible to perform such studies in humans, the brain circuits controlling stress responses and feeding are conserved across species.
People who were exposed to early life trauma have changes in the structure of their hippocampus. In humans, those consuming the most “western” diet had smaller hippocampal volumes, in line with data from animal models.
Taken together, these findings suggest future work should consider possible long-term effects of high sugar intake, particularly early in life, on the brain and behaviour.
Jayanthi Maniam, Research Associate, UNSW Australia and Margaret Morris, Professor of Pharmacology, Head of Pharmacology, UNSW Australia
This article was originally published on The Conversation. Read the original article.
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