Effectiveness of exercise for improving cognition, memory and executive function: a systematic umbrella review and meta-meta-ana..., 2025, Maher et al

Effectiveness of exercise for improving cognition, memory and executive function: a systematic umbrella review and meta-meta-analysis
https://bjsm.bmj.com/content/early/2025/03/06/bjsports-2024-108589

Abstract

Objective To evaluate systematic reviews of randomised controlled trials (RCTs) on the effects of exercise on general cognition, memory and executive function across all populations and ages.

Methods Systematic reviews and meta-analyses of RCTs evaluating the effects of exercise on general cognition, memory and executive function were eligible. Data extraction and risk of bias scoring were conducted in duplicate. The A MeaSurement Tool to Assess systematic Reviews (AMSTAR-2) was used to assess the risk of bias. Effect sizes were pooled using random effects models and reported as standardised mean differences (SMD). Subgroup analyses were conducted for participant and intervention characteristics.

General cognition, memory and executive function.

Data sources CINAHL, The Cochrane Library, Embase, MEDLINE via OVID, Emcare, ProQuest Central, ProQuest Nursing and Allied Health Source, PsycINFO, Scopus, Sport Discus and Web of Science.

Results 133 systematic reviews (2,724 RCTs and 258 279 participants) were included. Exercise significantly improved general cognition (SMD=0.42), memory (SMD=0.26) and executive function (SMD=0.24). Memory and executive function improvements from exercise were greater for children and adolescents than for adults and older adults. Those with attention-deficit/hyperactivity disorder exhibited greater improvement in executive function than other populations. Effects were generally larger for low- and moderate-intensity interventions. Shorter interventions (1–3 months) and exergames (video games that require physical movement) had the largest effects on general cognition and memory. Findings remained statistically significant after excluding reviews rated as low and critically low quality.

Conclusions These findings provide strong evidence that exercise, even light intensity, benefits general cognition, memory and executive function across all populations, reinforcing exercise as an essential, inclusive recommendation for optimising cognitive health.

 

We're going fractal with meta meta analyses (looking forward to the meta meta meta analyses) and systematic umbrella reviews (why not systematic square?). Because if you can polish some turds, you can also definitely polish polished turds some more.

Honestly, that's a whole lot for very little. This is thousands of trials. THOUSANDS! A quarter of a million participants across decades. And it's a small effect. With a misleading conclusion: "across all populations". This is not true. "Across most populations" is closer to the truth, but still, the evidence and the effect are quite weak. More importantly, it's not a linear process, so more is actually not better. And enough is actually very little, so little that most people meet it by simply living a normal life.

Not just that, but from the looks of it, it's actually cognitive effort that seems to be the key:

I bet you would find the same thing from video games that require no physical movement. Because, yeah, video games are pretty much some of the ultimate cognitive challenges. They can require fast thinking, strategic planning, tactical execution, and for sure a lot of working memory.

So it remains, after all this money spent, that a little exercise is a little good, while more exercise adds little, and even more adds nothing. It's overall good, just a little. If you add fun components, if it's mainly recreational, people find them enjoyable, and people who do enjoyable things are happier. But that's also true in general. And if you include components that require some thinking, then it will be a little bit good for thinking. And that's also true in general.

But the message is rather that this is good for everyone, for everything (imagine a world!), and I guess it means it should be prescribed by physicians, or something like that, entirely missing all the points.

The main takeaway is that the benefits are actually minimal. Which is fine and expected, there is no such thing as a panacea. But the benefits of exercise have been massively exaggerated for decades, promising something closer to the fountain of youth, when in reality, it's actually a little bit good, and not much more than that.

Can we freaking move on? No? Fine, keep plucking that chicken, then. It clearly has a few glued in feathers for several thousand people to dedicate themselves to ungluing and gluing back again.

 

Not even whelming. This is very underwhelming.

Same as with everything biopsychosocial, the more rigorous the assessment, the lower the effect. It's found all over the place, from "placebo" effects to the benefits of CBT and basically everything in their toolkit: the closer you look, the less of it there actually is.

This is a strong ceiling effect:

It's a small effect, and it maxes out very quickly. On a scale of pain medication, this is not even acetaminophen. Although I would disagree this is counterintuitive, it simply goes against a "common wisdom" that has established itself as dogma despite very little actual evidence, even despite very underwhelming evidence across the board.

There is some reasonable discussion of how novelty could be a part of it. Once someone learns the moves of an activity, there isn't much learning beyond it. Which could be why video games provide greater benefits, they are so much more varied than most forms of physical exercise, which tend to be very repetitive to the point of getting dull quickly.

So, novelty, experience, having fun doing different things, for the most part. But you can't forget the button, it's button soup after all.

 

I’m not going to trust a review of reviews, because I have zero confidence is the original assessments of e.g. risk of bias and methodological quality.

 

Ah, but what about a meta review of meta umbrella systematic meta analyses?

There's always another turtle down. Each turtle adds nothing to the stability of the system. Nevertheless, there is always another turtle. And another. And another. And, oh, a meta turtle. And back to another turtle.