By Matthew Lee ’21

It is well known that distress can have negative effects on both the brain and immune system. Previous studies have established that intermittent fasting (IF) can have positive effects on brain function and possibly on lifespan extension. However, IF was never examined for its potential as a source of eustress. A team of researchers led by Dr. Marjan Shojaie of Hormozgan University of Medical Sciences recently studied the effects of IF on cognitive function in mice. Key indicators of distress were the mice’s corticosterone,  a type of stress hormone, TNF-⍺, and IL-6 levels, molecules that promote inflammation.

Initially, the researchers took forty mice and divided them into four groups of ten.  Each group was subject to IF undistressed, no IF distressed, IF undistress and IF distressed respectively.  Electrical foot shock served as the distressor, and the fasting period extended for two hours a day. After 18 days, the mice were put through the Barnes maze to assess learning and memory functioning. After the maze, blood samples were drawn and the mice were sacrificed. Their adrenal glands and brains were removed for study.

The results indicated that distressed mice that underwent IF maintained higher brain weights as well as lower levels of adrenal hypertrophy compared to mice that experienced distress only. The distressed IF mice also had remarkably low corticosterone levels (~70 mmol/mL), compared to those that experienced distress only (~150 mmol/mL). Similar trends were observed for IL-6 and TNF-⍺ levels. Lastly, mice that fasted were able to escape the Barnes maze significantly quicker, in some cases more than 200 seconds faster, than their non-IF counterparts.

These findings are significant because they suggest that IF could have a role in mitigating the activation of the pro-inflammatory signalling pathway. This could reduce levels of committed macrophages (reducing IL-6 and TNF-⍺) and adrenal gland corticosterone secretion. Although further research should investigate the efficacy of IF as a long-term strategy for stress reduction, the results indicate that fasting can potentially increase cognitive functioning in distressed individuals.

References:

1. M. Shojaie, et. al., Intermittent fasting could ameliorate cognitive function against distress by regulation of inflammatory response pathway. Journal of Advanced Research 8, 697-701 (2017). doi: https://doi.org/10.1016/j.jare.2017.09.002
2. Image retrieved from: https://commons.wikimedia.org/wiki/File:Brain_power.jpg