Can a high-fat diet accelerate ageing-related memory loss? Study sheds light

Increased consumption of highly processed foods, which are rich in calories but poor in nutrients, has contributed to rising rates of obesity and related diseases like high blood pressure and type 2 diabetes mellitus. These conditions are risk factors for cardiovascular disease (CVD) and cancer.

Obesity is also linked to cognitive dysfunction, including anxiety, depression, memory decline, and impaired learning. Neuroinflammation, a consequence of obesity, further exacerbates cognitive impairment and neurodegeneration.

High-fat diets can induce inflammatory neuronal damage within a week of exposure, leading to dysregulated feeding and weight gain. Additionally, these diets can trigger hippocampal inflammation, resulting in memory deficits.

In the study, female rats were fed a high-fat and high-sucrose diet (HFSD) for eight weeks, and their brain microglia and inflammatory markers were examined. Rats consuming HFSD showed accelerated weight gain compared to those on a regular diet, with aged rats gaining weight faster than young rats.

Both groups also had increased fat mass, while lean mass decreased concerning fat mass. Aging was linked to higher microglia expression in the brain, particularly in the hypothalamus and hippocampus, with no further increase when rats were fed HFSD. Recognition memory declined with both aging and high-sucrose diet consumption, but high-sucrose diet did not exacerbate the effect of aging.

The findings suggested that aging and HFSD may affect rat behavior by causing cognitive deficits and anxiety, even when microglia are depleted. This indicated that microglia may not be the direct cause of cognitive dysfunction observed with aging and HFSD in the short term.

“These results indicate a potential disconnect between the peripheral pro-inflammatory response caused by HFSD and the central pro-inflammatory, or at least, primed, profile seen in aging. Our data suggest that mechanisms additional to the acute microglial contribution play a role in aging- and HFSD-associated memory dysfunction,” said the study authors.

Reference: Malik, S., Xavier, S., Soch, A., et al. (2024). High-fat diet and aging-associated memory impairments persist in the absence of microglia in female rats. Neurobiology of Aging. doi:10.1016/j.neurobiolaging.2024.04.010.