intermittent fasting

Blocked or reduced blood flow to the brain is the second-most common cause of dementia in humans.  A team of Chinese scientists used a rodent model to investigate whether intermittent fasting (IF) could help protect against cognitive impairment from vascular dementia.


As the name suggests, intermittent fasting (IF) describes a system of mixing periods of normal eating with periods of abstinence. There are many different IF frameworks. Partial day fasts are those in which a person eats only during a specific time window each day. Alternate day fasting is where a person chooses to eat whatever they want one day, and then nothing the next. While there are several reasons people choose to eat this way, one common rationale is to help teach the body to use the food it consumes more efficiently and to burn fat as fuel when it is deprived of continuous caloric intake.

Interestingly, some of the mechanisms largely responsible for weight loss and diabetic control when fasting also seem to help protect brain cells and make them more resilient. Preclinical studies in rodents suggest that long-term IF might also reduce cognitive deficits.

According to a study published May 2017 in the Journal of Nutrition, a team of Chinese researchers used adult rats weighing at least 200g to investigate whether IF could protect against cognitive impairment from vascular dementia. Two thirds of the rats were allowed to eat on demand and one third were put on an alternate day fasting regimen. Cognitive function was measured using novel object recognition tests to assess short term memory and the Morris water maze test to assess spatial learning.

After 12 weeks, half of the eat-on-demand rats and all of the IF rats underwent an operation to surgically close two arteries, to reduce blood supply to the brain and model vascular dementia.  Following a brief recovery period, cognitive function was retested. The rats were then euthanized so brain tissue could be collected and studied.

The research team found that IF prevented memory impairment, attenuated hippocampal neuronal apoptosis and increased synaptic density. In addition, examination of the brain tissue showed evidence that IF reduced inflammation and alleviated oxidative stress, thereby reducing the environmental toxicity in the hippocampi which can induce neural death and cognitive dysfunction.

While this study is promising, no human clinical studies have confirmed that IF (or even standard calorie restriction) promotes brain health or protects against dementia in healthy people. Additionally, IF may be unsafe for certain people, including individuals who are underweight, diabetic, ill, or frail.


Written By: Debra A. Kellen, PhD

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