【New Knowledge】The effects of sports doping on the brain

Today we're going to talk about a rarely discussed aspect of performance-enhancing drugs: the nervous system. The health effects of performance-enhancing drugs such as testosterone have always been unclear, in large part for one reason: They cannot be studied.

Due to various potential side effects, these performance-enhancing drugs cannot pass the review of ethics committees, nor can they be openly tested in clinical trials. Therefore, the health risks of performance-enhancing drugs are mostly inferred from observational/animal studies.

Today's protagonist is an observational study from Sweden. Although observational studies cannot be used to infer causal relationships, this study has strong logic and careful thinking and has high reference value. Therefore, Scott specially excerpted it for everyone to study carefully.

Performance-enhancing drugs and the nervous system

There is a legend in the fitness world: testosterone is the hormone that stimulates "masculinity". After injection, not only will the muscles become bigger, but the temperament will also become more aggressive, and even violent attacks may occur! However, these stories are just "urban legends" and have never been confirmed.

But in academic research, the impact of male hormones on the nervous system is more than just a legend. For example, those who use androgen have higher suicidal tendencies and higher rates of mental illness, and drug users also perform worse than ordinary people in tests of cognitive function.

Animal studies also support this theory: administration of androgens causes apoptosis of the mice's nerve cells, leading to premature onset of memory and cognitive dysfunction.

Swedish Studies

Bjørnebekk's 2016 study, published in the journal Biological Psychiatry, aimed to investigate differences in brain structure between real-world bodybuilders who used and did not take medication.

(Note: The following "banned drugs" all refer to androgen drugs.)

Bjørnebekk posted advertisements on local social networks and gyms in Sweden, recruiting 89 doping users and 70 non-users. Both groups were weight training veterans.

After recording the subjects' basic information, physical fitness, living habits, and competition events, Bjørnebekk had them undergo precise brain imaging examinations using magnetic resonance imaging.

Here are some interesting participant statistics:

The first thing that catches your eye is the IQ scores. Although the difference is not large, the IQ test scores of androgen users are significantly lower than those of non-users. Don't worry, this is an observational study, and we cannot conclude that androgen will harm higher cognitive functions.

Next, you can see that the two groups of people are about the same height, but their weight differs by a full six kilograms. Although this study did not measure body fat percentage, based on the deadlift, squat, and press performance of the two groups, I am confident that the body fat percentage between the two groups is not much different, and the muscle mass of the users is significantly greater than that of the non-users.

Non-users spent almost two hours more per week on strength training than users, but were significantly less powerful, which confirmed the known concept: testosterone can significantly increase muscle strength and muscle mass.

In addition, the rate of taking antidepressants (20%) and anti-anxiety drugs (17.3%) among drug users was significantly higher than that among non-users, which is consistent with previous literature showing that the prevalence of mental disorders among androgen users is higher than that of the general public. Once again, no causal relationship can be inferred from this report alone.

(Perhaps anxiety is what drives bodybuilders to use performance-enhancing drugs? That’s a plausible explanation, too.)

Next is the highlight of this article...

MRI measures brain volume

After measuring the subjects' brains with sophisticated instruments, Bjørnebekk found that the total cerebral cortex and gray matter volume of those who used androgen was significantly smaller than that of non-users. Simply put, the brain neurons of the drug users may have atrophied.

We can reasonably suspect that other confounding factors may have caused this result? For example, drug users have lower IQs and more abuse of other drugs, such as cocaine, which could explain the brain shrinkage.

But Bjørnebekk is a smart man. He input various parameters into the computer and used statistical methods to eliminate the influence of IQ, other drug abuse, and lifestyle. He found that the cerebral cortex volume of androgen users was still smaller. Moreover, as the duration of androgen use increases, the degree of brain shrinkage becomes more severe.

Simply observing that androgen users have smaller cortical volumes does not prove that androgen is the cause and cortical shrinkage is the effect.

However, if the atrophy in long-term users is more severe than that in short-term users or non-users, or if there is a dose-dependent response between the two, where the more and longer the user is used, the greater the damage, then the likelihood of a causal relationship increases significantly.

These two points are exactly why Scott recommends this study. Through clever statistical design and dose-response evaluation, the reference value of observational studies is greatly enhanced.

Conclusion

Animal experiments have shown that excessive androgen can cause apoptosis of nerve cells, observational studies have reported that androgen users have poorer cognitive function, and combined with the cerebral cortical atrophy observed in this article, I believe that the argument that "androgen abuse leads to neurodegeneration" is not an exaggeration.

In the world of top athletes, where a 1-2% increase in performance can mean the difference between success and failure, I can understand why many athletes use performance-enhancing drugs.

But for people who just do it for fun and don't make a living from competitive sports, should they risk the various side effects of using performance-enhancing drugs?

For me, the answer is clearly no.

This article comes from: Dr. Scott's One-Minute Fitness Class

※For more information, please see "Dr. Scott's One-Minute Fitness Class"