Content note: depression, suicide.

A friend I was discussing depression with linked me an article, "Most anguish isn't an illness but an evolved response to anxiety". It turns out it's a condensed version of a recent paper by Syme and Hagen, two biological anthropologists. The basic idea is that depression, anxiety and PTSD are not really disorders, but evolutionary adaptations, so we shouldn't try to cure them (though we could try to remove their causes).

I have analysed the article and paper at length because I wanted to give my friend a detailed criticism, and because it ties in nicely with my having recently updated my beliefs about psychiatry and starting to question some inherited anti-psychiatry memes.

Moreover, there is a whole class of articles and movements out there who say that "[insert mental condition] is not an illness and we should stop medicalizing it already". To the extent that they use similar arguments, my analysis should hopefully generalize.

Depression is not real. Is it?

The main problem I have with this work is that the authors are simultaneously denying the concept of depression and applying it in their analysis.

The article starts by saying that viewing depression and anxiety as illnesses is a "colossal error". Instead, they are adaptations designed by natural selection and activated by environmental factors, which the authors mainly identify with social conflict. They want to offer arguments against the "disease model" of depression and anxiety.

In the paper, they describe some well-known limitations of psychiatry. They attack the chemical imbalance theory of depression; point out that treating the symptoms is not the same as removing the causes; that common antidepressants have limited efficacy, though they are more effective than placebo; and that psychopharmaceuticals have aversive side effects.

In Section 5, the authors complain of the DSM's "stranglehold on research and policy". Unlike scientific taxonomies that cut reality at the joints, such as the periodic table of elements, the DSM's classification system is based on clusters of symptoms and is basically a mess. The DSM has too many diagnoses, is vulnerable to markets and fads, shows low validity and tends to over-diagnose in healthy populations.

I think most of these criticisms are justified, but the authors don't provide any workable alternative or new paradigm. In fact, after complaining of their dominance, they keep using the DSM categories in their work as if nothing happened.

Here we very tentatively offer a provisional evolutionary schema with the important caveat that because most research has used DSM categories, our schema relies on them too.

At the end of the paper, in their address to biological anthropologists, they simultaneously recommend and discourage the use of the DSM:

1. Consider investigating mental health issues in your study populations. As a starting point there are several survey instruments, based on the DSM or ICD, that have been developed for cross-national research.

2. Do not shackle your research to DSM/ICD categories and its symptom-based approach. The DSM/ICD symptom-based categories were largely developed based on inpatient populations in urban psychiatric hospitals in 19th and 20th century Europe and the United States.

What are their colleagues to make of this?

"Depression" itself is a psychiatric category. If you wish to argue that the concept has no validity, you should dissolve it into other phenomena as per the reductionist approach. The authors do attempt a reduction to biological adaptations, but their approach is half-baked.

First, they don't explain why the illusion that there is such a thing as "depression" arose in the first place. Why do states spend millions so people can study – and psychiatrists learn to treat – a condition that doesn't exist that so people who don't have the condition can get a cure they don't need?

Second, the authors keep using the concept of depression as a psychiatric category. From the article:

Globally, depression is the largest contributor to the burden of mental ‘illness’ by far.

A serious feat for a disorder that is not a disorder. From the paper:

We therefore propose that there is a group of mental disorders that are probably best explained by genetic-based developmental dysfunctions; a group that is probably caused by senescence; a group that might be caused by mismatches between modern and ancestral environments; and a group that are probably not disorders but instead are aversive and socially undesirable but nevertheless adaptive responses to adversity.

How can a "group of mental disorders" contain things that are "probably not disorders"?

Putting commas around 'illness' does not change the fact that you are analyzing depression as an illness. Denying that depression is a disorder does not change the fact that you are placing it in a taxonomy of mental disorders. Complaining against the "stranglehold of DSM" is absurd if you keep using its categories uncritically.

Finally, a list of psychiatry's problems does not automatically provide an argument for its dismantlement, especially if you are not suggesting any workable ideas for improvements or new paradigms.

Depression as adaptive response

The authors believe that the failures of psychiatry are partly due to its having failed to integrate evolutionary theory. They propose to use Wakefield's concept of illness as harmful dysfunction. Dysfunction indicates the "failure of a trait to perform its evolved function". Harmful "signifies an individual, social or cultural value judgment".

Allegedly, this concept can "help disentangle true disease states from conditions, like homosexuality, that are merely considered socially undesirable."

Wait, didn't they just say that "harmful" is an individual, social or cultural value judgment? How does that save homosexuality from being considered 'harmful' in the wrong context? It is exactly through an individual, social or cultural value judgment that homosexuality may be condemned. Today's dominant judgment is that it's not harmful, because our values have changed. But how would the harmful dysfunction illness concept have prevented our forefathers from seeing homosexuality as an illness?

Their approach to evolutionary theory is also problematic. Take the following quote:

It is an evolutionary paradox that many mental disorders are both harmful and heritable, because deleterious alleles should be eliminated by purifying selection.

But I see no paradox at all. First, the fact that some genes, present certain conditions, make people slightly more exposed to depression in our twenty-first century society, does not imply that they had the same effect in the ancestral environment. Imagine a gene that makes you depressed if you don't hunt and kill big animals. This gene would make you depressed today if, like most humans, you live in a city, but would have been quite adaptive in the ancestral environment. Second, deleterious to whom? To the individual? But evolution is not about individuals, it's about genes. Genes that make the individual miserable can be neutral or favorable from selection's point of view (see last section).

The authors believe that depression disorders, anxiety disorders and PTSD form a separate cluster from other psychiatric disorders such as schizophrenia, OCD, and bipolar disorder. This is justified on the following grounds: (1) they have relatively low heritability, (2) they are more prevalent, (3) they tend to appear at any age, (4) they tend to appear in response to adversities. The supporting data comes from a study by the Brain Consortium.

This is an interesting observation, of which I was not aware. Going through the Brain Consortium study, I find support for (1) and (2), while (3) seems actually falsified (see s.m., Fig. S1F), but I haven't seen the other studies that they're citing. I'm not sure about (4): are depression and anxiety more traceable to exogenous causes than schizophrenia and bipolar? Intuitively, I would say yes; it's easier to imagine someone getting depressed or traumatized over an aversive event, than suddenly becoming schizophrenic or bipolar.

In fact, I am willing to accept the authors' claim that depression appears in response to adversity. For example, they quote a study showing that

In conflict-affected countries, an estimated one in five people suffers from depression, PTSD, anxiety disorders, and other disorders, compared to 1 in 14 worldwide (Charlson et al., 2019).

The problem is in their conclusion:

Because many of their symptoms seem to be functional responses to threats, the hypothesis that they are functional responses to adversity is compelling.

Note the tautologicity of this statement. Likewise, in the article:

Consistent with our predictions, evidence from longitudinal studies in the United States and Europe indicates that major depression, PTSD and anxiety mostly follow adverse life effects, implying that they are often a reaction or defence against those events.

How does efficient cause automatically translate to functional cause? It's a long stretch from "depression follows adverse life events" to "depression is an adaptive response to adversity". At the very least, it seems that the proposition (depression arises because of X AND depression is a functional response to X) is more detailed than (depression arises because of X) and hence would need more proof.

The authors' strategy is to equate depression to pain and then show that pain is an adaptive response.

persistent sadness, low mood and andhedonia [...] are probably forms of "psychic pain" that adaptively focus attention on adverse events that would have reduced fitness [...] so as to mitigate the current adversity and avoid future such adversities.

This is very clear in the article:

Just because psychological pain is unpleasant to the self and others, that doesn't make it a disease, and we shouldn't seek in the first instance to blunt it with drugs or other medical interventions.

[...] psychological pain, like physical pain, probably evolved by natural selection, and in many or most cases is therefore not a disease.

[...] evolution has not shaped humans to be perpetually happy or free of pain.

(I must have missed the latest edition of the DSM which classifies depression as not being made of hedonium).

The authors take the easy way out by ignoring the specific (and I would add, maladaptive) features of depression. In fact, any mental problem can be described as adaptive, because it inevitably involves some emotion or other, and emotions are adaptive because they were designed by evolution, weren't they? So anxiety is characterized by "functional responses to genuine social and environmental threats". PTSD shows "functional responses to avoid future traumas", although the authors admit that other symptoms "are not clearly functional" (but they might be!). Even postpartum depression is "an adaptation that informs mothers that investment in a new offspring is unlikely to deliver fitness benefits".

Anyone can come up with a just-so story of how a condition is adaptive, but this does not constitute a proof. To prove that depression (or any other condition) is an adaptive response to averse events, one should at least: (1) show that there were specific evolutionary pressures to develop the adaptation, (2) describe the mechanisms that execute the adaptation, (3) show which factors in the current environment activate the adaptation.

The subject abandoned

The Depressed Person goes to the psychiatrist for her appointment.

Out come Syme and Hagen:

"You've nothing to do here. Go home."

"But... I was supposed to see Dr. Smith."

"There is no reason for you to see him. He'll just stigmatize you and mess with your brain. Besides, you're not even ill."

"But... I feel terrible. Most days I can't even get out of bed. Dr. Smith said I have major depressive disorder."

"And you believed him? Haha. Listen, don't beat yourself up. There's nothing wrong with how you're feeling. It's an evolutionary adaptation, you see?"

"But... It feels wrong."

"Of course it does! We didn't evolve to be in a perpetual state of orgasm, did we? Tell me now, did something particularly horrible happen to you recently?"

"Well, yes. I was assaulted and mugged on the street."

"There! A perfectly adaptive response to social conflict! Now, what would happen if you didn't feel any pain at all ?"

"Um... I'd feel a lot better?"

"Nonsense, nonsense. Listen, we'd love to stay and chat, but there's a psychiatrist who's trying to commit a suicidal person on the other side of town."

Critics of psychiatry typically say that it devalues people by stigmatizing them, labeling them as diseased, messing with their brains, closing them in institutions and so on. They, on the other hand, tend to style themselves as the defenders of the dignity and autonomy of the subject.

Consider what happens to the depressed person in Syme and Hagen's world. Their condition cannot be addressed because it is not an illness (no insurance for you, sorry) and there is no point in trying to cure an adaptation. Hence, the individual is left to their own devices. If they ask what they should do to feel better, one can do little more than shrug: "Nothing much. Not until we manage to eradicate the roots of social conflict, at least."

If you're one of the 7% of people who are depressed, you should hope that they are wrong and you don't live in that world, because if you do, your situation is quite hopeless:

If our hypothesis that depression is an adaptive, evolved defence is true, it wouldn’t offer much hope for a ‘quick fix’ or medical cure. [...] Just because psychological pain is unpleasant to the self and others, that doesn’t make it a disease, and we shouldn’t seek in the first instance to blunt it with drugs or other medical interventions. Instead, we should look to the social roots of adversity – to inequities, injustices and individual selfishness – and consider if and how we can harness mental anguish to help change ourselves, and other people’s lives, for the better.

Oh, and not only is your condition not an illness – you should harness your mental anguish to improve yourself and other people's lives. What are you achieving with your depression?

Panglossian evolutionism

The goal of theodicy is to connect evil and repulsive phenomena to the benevolent influence of God. No matter how horrible and absurd something is, it was made by God, and God has designed everything, and God is good, so that thing must be good too; you're just not seeing its goodness.

Analogously, there is a sort of panglossian evolutionism that aims to show that some undesirable conditions are actually good because they were put there by evolution, and evolution has designed everything, and evolution is good because it wants us to survive, so the condition must be good too; you're just not seeing its function.

The 1755 Lisbon Earthquake may be the most influential earthquake in the history of civilization. It encouraged the first embryonic studies of seismology. It changed the course of Portugal's history. Most importantly, it inspired Voltaire to ridicule Leibniz's theodicy, laying a cornerstone of enlightenment thinking. The earthquake struck on All Saints' Day, killed tens of thousands, and destroyed most of the city's churches. What benevolent God would do this?

The moral of the story is that panglossianism will not survive a close encounter with Nature.

From The Selfish Gene (chapter 7):

Sometimes, as we have seen, one member of a litter is a runt, much smaller than the rest. He is unable to fight for food as strongly as the rest, and runts often die. We have considered the conditions under which it would actually pay a mother to let a runt die. We might suppose intuitively that the runt himself should go on struggling to the last, but the theory does not necessarily predict this. As soon as a runt becomes so small and weak that his expectation of life is reduced to the point where benefit to him due to parental investment is less than half the benefit that the same investment could potentially confer on the other babies, the runt should die gracefully and willingly. He can benefit his genes most by doing so. That is to say, a gene that gives the instruction 'Body, if you are very much smaller than your litter-mates, give up the struggle and die', could be successful in the gene pool, because it has a 50 per cent chance of being in the body of each brother and sister saved, and its chances of surviving in the body of the runt are very small anyway. There should be a point of no return in the career of a runt. Before he reaches this point he should go on struggling. As soon as he reaches it he should give up and preferably let himself be eaten by his litter-mates or his parents.

As I read this passage, my immediate thought was: Maybe this is why we have depression. My second thought was: It's so horrible it just might be true.

If there was an evolutionary explanation for depression, this is exactly what I'd expect it to sound like. Perfectly logical and perfectly horrible.

Remember, selection is about genes. The individual is an adaptation executor, a machine meant to be discarded when it has exhausted its purpose. If you can't grow and reproduce, you might as well try to benefit the copies of your genes that will live on in your kin.

This is what depression would sound like in Darwinian idiom: "Body, you are useless. Lose all hope and interest in life. Stop eating and drinking. Lay down and die already so that your mother and siblings can eat you."

Turns out the idea of depression-as-adaptation is not that comforting after all.