Unhealthy Diet May Exacerbate Effects of Aging in Brain

July 9, 2018

When paired with normal aging, an obesity-inducing diet may contribute to the development of Alzheimer’s disease, suggests an animal study published in the journal Physiological Reports.

Researchers looked at the effect of a high-fat, high-sugar diet over 13 weeks on insulin signaling and markers of inflammation and cellular stress in middle-age mice. One group of mice received the obesity-inducing diet while another group ate a normal diet. Afterward, researchers measured inflammation and stress levels in the hippocampus, the area of the brain responsible for long-term memory, and the prefrontal cortex, which oversees cognitive, emotional, and behavioral function.

Compared to mice that ate a normal diet, mice that ate the high-fat, high-sugar diet had significantly higher markers of inflammation, insulin resistance, and cellular stress in area of the hippocampus believed to be involved in Alzheimer’s disease progression, researchers reported. While the prefrontal cortex also showed increased signs of insulin resistance, inflammation and cellular stress markers in that location did not change with the high-fat, high-sugar diet.

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The “region-specific differences between the prefrontal cortex and hippocampus in response to aging with a high-fat, high-sugar diet [indicates] that the disease pathology is not uniform throughout the brain,” researchers observed.

Compared to baseline readings, inflammation levels also were higher after the trial among mice who ate a normal diet. The finding is consistent with the theory that aging alone plays a role in Alzheimer’s disease progression and that obesity exacerbates the effect of aging on the brain.

“This study provides novel information in relation to the mechanistic link between obesity and the transition from adulthood to middle age and signaling cascades that may be related to [Alzheimer’s] pathology later in life,” researchers wrote. “These results add to our basic understanding of the pathways involved in the early progression of [Alzheimer’s] pathogenesis and demonstrate the negative effects of a high-fat, high-sugar diet on both the prefrontal cortex and hippocampal regions.”

—Jolynn Tumolo

References

Baranowski BJ, Bott KN, MacPherson REK. Evaluation of neuropathological effects of a high-fat high-sucrose diet in middle-aged male C57BL6/J mice. Physiological Reports. 2018;6(11):e13729.

Obesity + aging linked to Alzheimer’s markers in the brain [press release]. Rockville, Maryland: The American Physiological Society; June 28, 2018.