Aerobic Exercise Improves Cognition in Younger Adults, As Early as 20.

Bad news for all of you under 40 somethings that just like to lift weights in the gym.  Happily skipping your cardio and assuming it can wait until you are older. Thinking you just need to add in a few weeks’ worth to get ripped for the summer.  It turns out that new research just published in the journal Neurology has shown that aerobic exercise improves cognition in younger adults.  Previous research has shown many benefits for older adults but now we have clinical proof that individuals as young as 20 show marked improvement in executive function with aerobic exercise. 

Executive function relates to your ability to plan, organize and complete tasks including managing your time, staying focused and regulating emotions.  So essentially most everything you need to be a well-functioning, productive, successful person.

In the study 132 people between the ages of 20-67 with below average aerobic capacity (out of shape) were assigned to either a group that did aerobic activity 4 times a week or a group that did stretching and core exercises without aerobic activity.  The study lasted for 6 months. 

For the first two weeks the subject’s exercised at 55-65% of their maximum heart rate, a very gentle introduction to exercise.  They then gradually increased their heart rates so that by week 5 through the end of the study they were working at 75%.  Still a very moderate and comfortable pace.  The subjects could choose what form of aerobic exercise they wanted to perform and wore heart rate monitors to ensure they were working at the appropriate intensity.

At 6 months the subjects in the aerobic exercise group showed significant improvements in their executive function.  Not only did the subjects show improvement at all ages, including as young as 20, the subjects who were 40 tested as if they were 10 years younger, and the subjects who were closer to 60 tested as if they were 20 years younger. 

According to study author Yaakov Stern, PhD “As people age, there can be a decline in thinking skills, however out study shows that getting regular exercise may help slow or even prevent such decline.  We found that all participants who exercised not only showed improvements in executive function but also increased the thickness in an area of the outer layer of their brain.”

What does this mean for you?  One more reason why you can’t skip cardio.  Yes, plenty of articles these days say you can manage your metabolism and optimize training by doing primarily resistance work and incorporating higher intensity techniques such as HIIT.  While those pieces are amazing and belong in your routine for several reasons, good old fashioned sustained aerobic exercise still has a vital place in an optimal fitness and health program.  Protecting and improving executive function being one of the big reasons.  As for all of you 20-40-year old’s, the clock starts ticking earlier then we thought it did and you need to begin banking the benefits in your 20’s, or however old you are while you are reading this.  Now get up and go do your cardio.

Stern, Y., MacKay-Brandt, A., Lee, S., McKinley, P., McIntyre, K., Razlighi, R., Agarunov, E., Bartels, M. and Sloan, R. (2019) Effect of aerobic exercise on cognition in younger adults.  A randomized clinical trial.  Neurology, DOI: 10.1212/WNL.0000000000007003

Salt Is Making You Dumber. Probiotics To The Rescue.

We have all recently seen a lot of information released regarding the connection between the gut and other aspects of our health.  Now we have one more that shows a significant connection between salt consumption, our gut and our intelligence.  Yes that’s right.  The impact of salt on your gut may be making you dumber as read this so hurry up and finish this article before you eat all of those chips.

A recent study published in Nature Neuroscience (Faraco et al. 2018) found that a high salt diet in mice led to reduced blood flow to the brain, damage to blood vessels in the brain and lower scores on tests of cognitive function.  What was most interesting about these findings was they were not the result of increases in blood pressure due to a high sodium diet but due to an immune system reaction that occurred because of the action of the salt in the gut.

The mice fed a high salt diet had an immune reaction in their small intestines where TH17 cells are stimulated resulting in the release of a substance called interlukin-17 (IL-17). The IL-17 is an inflammatory substance that sets off a reaction that results in damage to the inner lining of small blood vessels in the brain. This led to a decrease in blood flow to areas of the brain strongly involved in learning and memory which in turn led to measurable cognitive declines.  When the high salt diets were stopped the mental performance of the mice returned to previous levels.

Yes you are sitting there saying “this was in mice, I’m a human”.  Very true, or you are the smartest mouse ever working the internet and reading this article.  However the physiology of mice and the reactions they have is very similar to humans and that is why they are so commonly used in early studies.  While we cannot say conclusively the exact same reaction will happen in humans, researchers strongly suspect it will.

So there you have it, one more very scary reason to cut back your sodium intake.  Unless you are so addicted to the salt lick that you can no longer comprehend what you just read and the danger that high sodium intakes have.

Probiotics To The Rescue

Those tricky TH17 cells don’t only appear to have impacts on the brain through non-blood pressure related mechanisms, they also stimulate inflammatory processes that lead to increases in blood pressure.  So essentially it sounds like they are trying to get you no matter what through multiple pathways.  And in a way they are but there is hope and it looks like those Whole Foods loving, health food store advocates have had the answer all along, probiotics.

A study published this past November (Wilck et. at. 2017) fed our old mice friends a high salt diet and watched as the number of TH-17 cells increased in response.  Along with that there was a significant decrease in a type of gut bacteria called Lactobacillus murinus and to no one’s surprise, blood pressure went up.

When the subjects were given a probiotic with Lactobacillus murinus they experienced a reduction in both TH-17 cells and blood pressure.  Score one for the probiotics.

A small study with human subjects was then done where the subjects were given a high sodium intake for two weeks.  They experienced a reduction in their lactobacillus counts while there was an increase in the number of TH-17 cells and blood pressure.

When subjects were given a probiotic for a week before the high salt diet began their lactobacillus levels and blood pressure remained normal while on the high salt diet.  Score two for probiotics.

So once again we are a seeing links between the gut microbiome and our health along with more evidence that high salt intake is a bad for us.

This isn’t the first time that probiotics have been suggested to lower blood pressure.  If we step into the way back machine a meta-analysis conducted in 2014 by Khalesi et al. found a positive effect of probiotic consumption.  The study suggested that the effect was greatest on individuals who already had high blood pressure, consumed a probiotic with multiple species, took them for greater than 8 weeks and at higher doses, greater then 1011.

Keep an eye out for upcoming articles about the microbiome, how it impacts our health and what we can do to optimize it.


Faraco, G., Brea, D., Garcia-Bonilla, L., Wang, G., Racchumi G., Chang, H., Buendia, I., Santisteban, M., Segarra, S., Koizumi, K., Sugiyama, Y., Murphy, M., Voss, H., Anrather, J. and Iadecola, C. (2018) Dietary salt promotes neurovascular and cognitive dysfunction through a gut-initiated TH17 response. Nat Neuroscience: Jan 15 (epub).

Khalesi, S., Sun, J., Buys, N. and Jayasinghe, R. (2014) Effect of probiotics on blood pressure: a systematic review and meta-analysis of randomized, controlled trials. Hypertension: Oct; 64(4):897-903.

Wilck et at. (2017) Salt-responsive gut commensal modulates TH17 axis and disease.  Nature: Nov 30; 551(7682):585-589.