We all know we need to eat “brain-boosting” foods like blueberries, fish oil, and turmeric. But what can be as important as what you eat is when you eat it.
A growing number of animal studies on intermittent fasting are addressing this very concept: by cutting off food for part or all of the day over time, we can improve the functioning of our brains. But here’s the catch: studies in mice or rats don’t mean the same thing in humans – but chances are intermittent fasting works in a similar way in our brains. And that deserves further detailed research on humans.
At the moment we know the following: Studies in which mice and other animals were fasted intermittently had surprising effects – including on long-term memory.
What’s new – mice may not remember childhood memories. We can’t ask them, of course. But when mice are on an intermittent fasting diet, they seem to retain information much longer than their non-sober counterparts.
The latest evidence for this is outlined in a new study published in Molecular Psychiatry on Tuesday. In this study, researchers found that laboratory mice that ate every other day appeared to have better memories than mice that were on a restricted diet and mice that ate whenever they wanted.
The mice that fasted every other day performed better on a maze test than mice that ate 10 percent fewer calories per day (this reduction was decided because the mice that fasted intermittently ate 10 percent fewer calories overall). The only difference in their diet was the timing.
The researchers placed the mice in a Morris water maze, which forces mice to swim through a maze to achieve the safety of an escape platform. After staying in the pool several times, they learn to take more and more direct routes to the escape platform – that is, they begin to remember the most efficient routes.
Mice in a mouse swim test remembered intermittent fasting best – as opposed to Alice.Getty / Andrew_Howe
The mice that ate every other day performed better than any of the other groups of mice on this test after 10 days. The researchers later examined the brain tissue of these mice and found that the intermittent fasting mice showed more neurons in the hippocampus – an area of the brain that plays an important role in memory and learning. These mice also showed an increase in activity in a gene called clotho. This gene codes for a protein that is believed to increase cognition in both mice and humans.
Taken together, these observations were likely related – and intermittent fasting, the researchers conclude.
Here’s the background: Intermittent fasting is often opposed to calorie restriction – that is, a diet where you eat fewer calories each day – because proponents claim that both therapies could have similar health benefits, but timed fasting isn’t as much of a hassle means like reducing food intake.
The reason people stick to an intermittent fasting program more successfully than dieting is because they can eat whatever they want during the “feeding phase” rather than counting calories. In theory, this approach can be useful in treating conditions such as diabetes, metabolic syndrome, and even diseases that affect the brain.
But the science of intermittent fasting is inconclusive – and one of the puzzles is whether it has any detectable effect as good or better than reduced calorie diets. In one study, fasting on the second day improved cognitive function in mice compared to a high-fat diet or a “normal” diet (eat whenever you wanted). In another study, also in mice, intermittent fasting appeared to lead to the formation of more brain cells and stronger connections between them. Intermittent fasting has also shown promise for reducing the signs of Alzheimer’s disease – but again, here is the study in mice.
Why It Matters – In the new study, researchers show that intermittent fasting compared to a low calorie restriction (10 percent) can make a bigger payoff for brain health: in particular, better memory retention and more brain cells.
What is important is that intermittent fasting is not compared to a more extreme calorie restriction in this study, the researchers write. Such extreme diets are the norm in many other mouse-based experiments used to demonstrate the health and brain benefits of calorie restriction.
In a laboratory, it is possible to cut a mouse’s diet by almost half – but it would be extreme for a human to follow such a regimen. However, a 10 percent calorie restriction may be more realistic for humans and, in theory, may be easier to achieve if you eat in specific time windows.
What We Don’t Know – It’s still unclear whether the memory effect seen in mice affects real people or not. There are few studies that have looked at the potential cognitive effects of intermittent fasting on human cognition. Studies of ketogenic diets, which are in some ways similar to fasting, have found limited success.
We also don’t know if the brain’s benefits for the sober mice are due to timing or if they get more exercise. The authors note that the fasted mice were more physically active, so there may be a crucial element in this relationship that we need more research to pull apart.
However, the authors write that the next step in answering the question would be to conduct clinical studies comparing the effects of intermittent fasting with calorie reduction in people with certain brain disorders, such as: B. Depression, anxiety and Alzheimer’s for several months. Interestingly, the gene they highlight in the new Klotho study could play a future role in developing drugs that mimic the brain-boosting effects of fasting. Intermittent fasting itself could also be used as a cognitive enhancer that many (many) already believe it is.
Abstract: Daily calorie reduction (CR) and intermittent fasting (IF) improve longevity and cognition, but the effects and mechanisms that differentiate these two paradigms are unknown. We investigated whether IF in the form of feeding every other day improves cognition and neurogenesis of the hippocampus in adults (AHN) compared to daily CR intake of 10% and ad libitum conditions. After 3 months on IF, female C57BL6 mice showed improved long-term memory retention. IF increased the number of BrdU-labeled cells and neuroblasts in the hippocampus, and microarray analysis showed that the longevity gene Klotho (Kl) in the hippocampus was only upregulated by IF. In addition, we found that downregulation of Kl in human hippocampal progenitor cells resulted in decreased neurogenesis, while over-expression of Kl increased neurogenesis. Finally, a histological analysis of the brains of Kl knockout mice indicated that Kl is required for AHN, particularly in the dorsal hippocampus. These data suggest that IF is superior to 10% CR in improving memory and identifies Kl as a novel candidate molecule that regulates the effects of IF on cognition, likely via AHN improvement.