Alzheimer’s Risk Linked to Aging Made Worse by Diets High in Fats and Sugars, Study Shows

Joana Carvalho, PhD avatar

by Joana Carvalho, PhD |

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diet, aging and Alzheimer's

The combination of two factors, aging and eating foods high in sugar or fats, raises susceptibility to Alzheimer’s disease, a study in mice reports.

The research, “Evaluation of neuropathological effects of a high‐fat high‐sucrose diet in middle‐aged male C57BL6/J mice,” was published in Physiological Reports.

Alzheimer’s disease is a progressive neurodegenerative disorder marked by a continued diminishment in cognitive abilities.

Although older age is the major risk factor for Alzheimer’s,  bad eating habits are also implicated in its development. Previous studies have reported that diet‐induced obesity affects brain insulin metabolism and, consequently, the energy status of nervous tissues. This, in turn, contributes to the production of amyloid plaques — clumps of abnormal proteins in the brain — that damage and eventually kill nerve cells.

Using a mouse model of middle-age animals and diet-induced obesity, researchers at Brock University in Canada studied how changes in insulin metabolism, energetic stress, and inflammation might relate to Alzheimer’s disease.

Animals were randomly distributed into two groups: those fed with a high-fat and -sucrose (sugary) diet and those fed normally (control diet) for 13 weeks. Twelve mice who were 20 weeks of age – considered middle-age – were selected for each group.

As expected, mice on the high-fat and -sucrose diet rapidly increased body weight (30%) and percentage of fat mass (28%) while dropping in lean mass (33%) compared to control diet animals.

After 13 weeks, at age 33 weeks, investigators collected samples from two distinct brain regions: the prefrontal cortex, involved in complex cognitive functions; and the hippocampus, linked to memory and spacial awareness.

The prefrontal cortex of mice fed the high-fat and -sucrose diet showed signs of energetic stress.  The hippocampus showed signs of insulin resistance and higher levels of inflammation and cellular stress in control mice at the study’s conclusion compared to 13 weeks earlier — a change attributed to aging. But the damage seen in the normal-diet group was exacerbated in mice receiving the high-fat and -sucrose diet, who were also older.

Researchers believe this data demonstrates that bad eating habits worsen the effects of aging in the brain, which are strikingly different between the prefrontal cortex and the hippocampus.

“These results add to our basic understanding of the pathways involved in the early progression of [Alzheimer’s disease] pathogenesis and demonstrate the negative effects of a HFS [high-fat and -sucrose] diet on both the prefrontal cortex and hippocampal regions,” the scientists wrote. Specifically, they “demonstrate that aging combined with a HFS diet exacerbates the effects of aging on inflammation/stress … in the hippocampus, and energetic stress in the prefrontal cortex.”