Epistemic Spot Check: Exercise for Mood and Anxiety (Michael W. Otto, Jasper A.J. Smits)

Introduction

Everyone knows exercise (along with diet and sleep) makes a big difference in depression and anxiety. Depressed and anxious people are almost by definition bad at transforming information about how to improve their lives into actions with large up front costs, so this data is not as useful as it might be. Exercise for Mood and Anxiety (Michael W. Otto, Jasper A.J. Smits) aims to close that gap by making the conventional wisdom actionable. It does that through the following steps:

1. Present evidence that exercise is very helpful and why, to create motivation.

2. Walk you through setting up an environment where exercise requires relatively little will power to start.

3. Scripts and advice to make exercise as unmiserable as possible while you are doing it.

4. Scripts and advice to milk as much mood benefit as possible from a given amount of exercise.

5. An idiotic chapter on weight and food.

Parts 3 and 4 use a lot of techniques from cognitive behavioral therapy and mindfulness, and I suspect there’s a second order benefit of learning to apply these techniques to a relatively easy thing, so you can apply them to the rest of your life later.

Epistemic Spot Checking

Claim: “a study of 55,000 adults in the United States and Canada found that people who exercised had fewer symptoms of anxiety and depression.” (Kindle Locations 103-104).

Correctly cited, paper has no proof of causation. (abstract) (PDF) The study does in fact say this, but it also says “Despite the fact that none of these surveys [of which this paper is a metaanalysis] was [sic] originally designed to explore this association… “. I’m not saying you can never repurpose data, but with something like this where the real question is causality, it seems suspicious. The authors do consider the idea that causation runs from mental health (=energy, hopefulness, executive function) -> exercise and dismiss if, for reasons I find inadequate.

Claim: “Other studies add to this list of mood benefits by indicating that exercise is also linked to less anger and cynical distrust, as well as to stronger feelings of social integration.” (Kindle Locations 104-106).

Correctly cited, paper has no proof of causation. (Abstract).

Claim: And these benefits don’t just include reducing symptoms of distress in people who have not been formally diagnosed with depression or anxiety. The benefits of exercise also include lower rates of psychiatric disorders; there is less major depression, as well as fewer anxiety disorders in those who exercise regularly. (Kindle Locations 107-109).

Correctly cited, paper has no proof of causation.

The dismissal of causality goes on for another three citations but I’m just going to skip to the intervention studies. Otto gives these population studies more credence than I would but does note that the intervention studies are more informative.

Claim: study summarized 70 studies on this topic and showed that adults who experience sad or depressed moods, but not at levels that meet criteria for a psychiatric disorder, reliably report meaningful improvements in their mood as they start exercising. (Kindle Locations 116-117).

Correctly cited, study accuracy undetermined. (Full paper). My fear (based on spot checking a similar book you’ll see in the rejects post) is that each of these studies consists of 15 people. All the metaanalysis in the world won’t save you if you do 100 small studies and only publish the 50 that say what you want. The studies included go all the way back to 1969: I can’t decide if that makes them more informative or less.

Claim: The latest estimates are that about 17% of adults experience a major depressive episode in their lifetimes and that about half who have it experience recurrent episodes over time. (Kindle Locations 124-126).

True. (Full paper). The same study is cited for both facts, but I can only find the 50% statistic in the paper. The data is kind of old (started in 1981), but of course you can’t get 30-year data except by starting 30 years ago. This paper says the lifetime prevalence of mood disorders (depression, bipolar 1 and 2, and their baby siblings) is 20%; this study puts prevalence in the US at 16.9%.

Claim: As is the case with major depressive disorder, anxiety disorders are common, affecting more than 1 in 4 (28.8%) adults in their lifetimes” (Kindle Locations 136-137).

True. (Full paper). He cites the same paper I did for the 20% mood disorder statistic.

Claim: [Anxiety disorders] tend to be especially long-lasting when people do not receive treatment. (Kindle Locations 137-138).

True, although not particularly specific. (Full paper)

Claim: Exercise in itself is a stressor—it requires effort, and it forces the body to adapt to the demands placed on it. (Kindle Locations 141-142).

True. (Full paper).

Claim: A study examined firefighters reaction to stress, and then gave half a 16 week exercise course. The study group showed improvements in stress responses. (Kindle location 148)

True. (Abstract) (PDF). I really like this study. The group presumably had a high baseline fitness level, so this isn’t the difference between couch potato and a walk. And they have before and after metrics. The study is marred only by the small sample size (53).

Claim: “stress plays a key role in both the development and the continuation of depression and anxiety disorders.” (Kindle Locations 152-153).

Accurate citation, very complicated topic. (Abstract).

Okay, it is becoming clear I don’t have the time to check every one of these citations and you don’t have time to read it. From here on out please assume a baseline of very dense citations, all of which accurately report the study results, if with a little more confidence than the study design merits, and I’m only going to call out things that deserve special attention on account of controversy or importance.

Claim: exercise increases serotonin just like the primary class of anti-depressants, selective serotonin update inhibitors.

True but less relevant than implied. They’re relying on a model of how SSRIs treat depression that is fairly outdated. SSRIs definitely increase serotonin, it’s just that there’s no evidence that’s their mechanism of action against depression except that they do it and they treat depression. “Depression is caused by a serotonin deficiency” is a lie simplification told to patients and their families to allay fear and shame around psychiatric treatment. This doesn’t undercut their point that exercise is good for you, but does indicate this is not a great book to learn brain chemistry from.

Claim: Both aerobic (prolonged moderate exercise such as running, cycling, or rowing over time) and anaerobic (like weight lifting or short sprinting) exercise have been found to be effective for decreasing depression, (Kindle Locations 239-241).

True. (Study 1 PDF) (Study 2 abstract).

Empirical Results

The theory behind this book is very well supported; the prescriptions it makes flow naturally from the theory, but the authors present no direct evidence that they work. I’m torn about this. I don’t want to engage in RCT worship; having a systemic understanding of a problem is even better than evidence a particular solution worked better or worse than another solution in a different population. On the other hand, humans are very complicated and it’s easy to identify the problem but guess the wrong solution.

I couldn’t test any of this on myself because I already enjoy exercise for a lot of reasons, so I scrounged up an unscientific sample from my wider social network to try it.

14 people filled out the pre-book survey. 3 people filled out the post-attempt survey. None of them exercised more.

Summary

The theory sections of this book are my high water mark for scientific rigor in a self-help-psych book. I’m currently reading a lot of those with the goal of finding out how much rigor is reasonable to expect, so that’s high praise.

The book walks the very fine line between reassuring and condescending, which is pretty unavoidable with CBT and mindfulness.

I did not like the last chapter and recommend skipping it. It feels like they tried to stuff all the usual diet-and-exercise stuff in at the end. Some of my problem is I think their recommendations are wrong, and some is that I believe that even if they were correct, throwing them in at the last minute undercuts the message of the book.

The first part of this is that, in America, at least in certain subcultures, any mention of weight makes the whole thing About Weight. Too many people use health or mood as a socially acceptable way to say “you’re not hot enough”, so any mention of weight in the context of diet or exercise automatically makes weight the real topic of the conversation. If the improvements in mood are enough of a reason to exercise, let them be enough, and the weight loss can be a pleasant surprise or not happen, and both are okay because you got what you came for.

The authors compound this problem by using Body Mass Index as a guide for goal weight. BMI is completely unsuited for use in individuals, even more so for people who just started gaining muscle mass. If you must talk about fat in the context of health use body fat percentage or certain circumference ratios (e.g. wrist:stomach).

The second problem is the speed with which EFMaA tries to address nutrition. The book (correctly) treats exercise as a thing that is challenging to start despite all its benefits, and spends 10 chapters explaining why it’s worth trying and providing scripts to make it workable for you, for the sole benefit of mood, ignoring everything else you might get out of exercise. I don’t know why the authors thought that that required an entire book but the even more complicated of nutrition for every possible benefit of nutrition could be squeezed into half a chapter. I would be have been very excited for another book by the same authors about how to implement healthy eating, but the half assed treatment here makes me pause.

They also present a particular diet as the settled science, when there is no such thing in nutrition. “Eat produce and fish” is fairly uncontroversial, but they recommend a lot more refined grains than many other people. I don’t know who is correct, but it was disappointing to see a book that had been so rigorous up to that point blithely paint over controversy.

[I have emailed Michael Otto about the handling of nutrition and have yet to hear back].

Speaking of which Exercise for Mood and Anxiety mentions that both aerobic (cardio) and anaeorbic (weights) are good for mood, but every single example is cardio, with an occasional cardio + core strength.

Mixed in through the book are tales of how Olympic athletes motivate themselves. This feels spectacularly irrelevant to me. I don’t want to win a gold medal, I want to climb V2s and be happy.

You might find this book valuable if:

• You want some ideas (although not conclusive proof) around how exercise helps mood.

• You want to want to exercise, and want scripts and tools to transform that into “want to exercise right now.”

• You find exercise unpleasant and want to get the best trade of unpleasantness-for-benefits possible.

• You would like to treat a mood issue with exercise (whether it reaches the level of official disorder or not).

• You want to change how you think about exercise (for improving your mood or something else).

• You are interested in CBT or mindfulness and want to practice with the large print version before tackling them directly.

• You think you are different than my test audience.

You probably won’t find this book valuable if:

• You already have an exercise program you are happy with.

• You have body image or eating disorder issues (last chapter only, and a single section of the 10th, the rest of it is fine).

• You want prescriptions for a particular exercise program, as opposed to general principles.

• You want to learn the nitty gritty of how exercise affects mood.

• You are similar to my test audience.

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