Most People Experience “Mental Illness” By Age 32

By Neuroskeptic | September 12, 2009 11:30 am

Mental illness: how common is it? A popular answer is one in four – 25% of people will experience it at least once in their lives. In fact, most published research suggests that the lifetime rate is higher, around 30-50%, in Western nations.

That’s a lot. But even this may be a serious underestimate, according to a new paper, How common are common mental disorders? The study compared the proportion of people reporting mental illness under two different research methods: retrospective and prospective.

Retrospective means asking people to think back and remember whether they ever have felt a certain way. A prospective study, however, recruits people and then follows them up for a certain length of time, asking them how they feel at regular intervals.

The obvious advantage of prospective studies is that there is less chance of forgetting. In a retrospective study, people are required to remember how they were feeling years, or even decades, ago. Human memory just isn’t that good. A prospective study requires some remembering, as people are generally asked to report how they’ve felt over the last year, but this is clearly less problematic.

The prospective study in question here included 1,000 people from Dunedin, New Zealand. The volunteers were followed from birth to age 32, and were interviewed at ages 18, 21, 26 and 32. The results were compared to three large retrospective lifetime studies, two American and one from NZ. (1,2,3).

50% of the Dunedin prospective cohort reported at least one “anxiety disorder”, 41% reported “depression”, 32% confessed to “alcohol dependence” and 18% to “cannabis dependence”. (Those were the only conditions studied.) For some reason, we’re not told how much overlap there was, but even assuming there was a lot, well over half of all the cohort will have experienced at least one disorder. If the overlap was low, it could be almost all of them. And remember, this is just up to age 32. And there still may have been some forgetting…

Compared to the retrospective studies, these rates are all about twice as high. What does this mean for psychiatry?

First, it suggests that retrospective studies, which are by far the most common, are flawed. People just tend to forget a lot of “mental illness” when asked to remember across the lifetime. More evidence for this comes from the fact that the ratio of past-year to lifetime reported disorders was 38% in the prospective study compared to about 60% in the retrospective ones.

But there’s a more profound implication. A growing number of critics have argued that the very high reported lifetime rates of mental disorders mean that the way most psychiatrists diagnose mental illness is flawed. The “Bible” of modern psychiatric diagnosis is the Diagnostic and Statistical Manual (DSM) of Mental Disorders of the American Psychiatric Association. DSM diagnostic criteria were used in the studies in question here.

These results suggest that DSM diagnoses are even more common than previously believed, which only strengthens the critics’ case. According to DSM criteria, at least 40% of people experience “Major Depressive Disorder” by age 32.

In which case, what is it? A fairly usual part of human life. So, calling it a disease and treating it with drugs or therapy seems rather presumptuous. Especially since so many people who “suffer” from it manage to not only get over it, but actually forget it ever happened. (Of course, this shouldn’t be taken to mean that real, serious clinical depression doesn’t exist.)

The authors conclude – listen carefully –

This article is uninformative (and agnostic) about the validity of diagnoses as defined by DSM-IV … [rather], objections voiced to surveys’ higher than expected lifetime prevalence of disorder are objections to prevalence that is only half what it could be in reality…

Researchers might begin to ask why so many people experience a DSM-defined disorder at least once during their lifetimes, and what this prevalence means for etiological theory, the construct validity of the DSM approach to defining disorder, service-delivery policy, the economic burden of disease, and public perceptions of the stigma of mental disorder.

That hammering sound you hear is another nail sealing the coffin of DSM’s credibility. If many* DSM “disorders” are simply descriptions of normal parts of human life, we need to take a long, hard look at those “disorders”, and rethink whether they need to labelled and treated as medical problems.

The newest edition of DSM, DSM-5, is currently in development. This would seem like a great opportunity to do just that. Unfortunately, the development process is rapidly degenerating into farce. If DSM-5 does not address the issues raised here, many people will be tempted to give up on DSM entirely.

* Not all: the great majority of people will never meet criteria for schizophrenia or bipolar disorder, for example.

ResearchBlogging.orgMoffitt, T., Caspi, A., Taylor, A., Kokaua, J., Milne, B., Polanczyk, G., & Poulton, R. (2009). How common are common mental disorders? Evidence that lifetime prevalence rates are doubled by prospective versus retrospective ascertainment Psychological Medicine DOI: 10.1017/S0033291709991036
CATEGORIZED UNDER: 1in4, mental health, papers
  • David

    I totally agree that “mental illness” is normal, based off the amazing amount of people I know who've struggled with mental issues of some variety.

    My concern is that this leads to a slippery slope where normal human experience is deemed worthy of medicating.

  • Socrates

    Around 0.8% of the human race has been dragged into the world of psychiatry with the diagnosis of Asperger's Syndrome.

    Although many of these people face significant challenges in their lives (a great number of which stem from other people's behaviour and attitudes towards them), most of these problems find their solution in social care and good educational provision – not medicalisation.

  • pj

    Alternatively to impugning the DSM criteria themselves, a possibly line of argument might be that these structured diagnostic interviews are pretty pants – certainly I am unimpressed by the SCID and its compatriots, which seem to seriously overestimate things like major depressive episodes because of their downplaying of social dysfunction criteria. They're also pants for substance misuse.

  • Sebastian

    Chinese medicine model of health suggests change between different emotions are normal and neccessary way of life und bodyily functions.

    While extremes of emotions could indeed be harmful, illnes is defined as stagnation in any certain emotional or bodily state.

    A luck of a unified model of health and disease in modern medical research has been critized by A. Fava. The Intellectual Crisis of Psychiatric Research. Psychother Psychosom 2006;75:202-208

  • Neuroskeptic

    pj: Fair point, but the criteria themselves don't help in that regard:

    “The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.”

    What's clinically significant?

    I had a research volunteer who considered themselves to have been depressed and said it impacted their lives because it made them do less sport. But they were still playing sports every week. And their social, educational etc lives went on as normal. I would call that non-significant, but that's my opinion vs. theirs. The criteria don't give much guidance.

  • pj

    I think that;'s part of my poin – you see someone in clinical practice and if they've made it to secondary care it is pretty likely they've got significant distress or dysfunction – you ask someone you've randomly selected off the street less so.

    Which suggests that a bit more work is in order defining it, as you imply.

  • pj

    This comment has been removed by the author.

  • Neuroskeptic

    Sebastian: I hadn't come across that paper. Thanks.

    pj: True, although secondary care psychiatrists rely on primary care physicians for referrals and maybe this is where more clarity would be especially useful.

    On that note, there are a bunch of articles in the latest Bulletin of the Royal College of GPs dealing with GP diagnosis of depression / antidepressant prescribing. They look interesting & controversial, but I can't access them. I think only College members can do so.

    So if any GPs are reading this and feel like doing me a favour…

  • drbuzz0

    Perhaps we need to take another look at how we think of “mental illness” or even consider whether the term is deceptive to the general public.

    I can see how most people could be defined as mentally ill at some point in life.

    I generally consider myself mentally healthy and I am definitely sane, but in the past I've had some times when I was really bothered by persistent stress – getting worked up about something that was bothering me and not being able to stop thinking about it, even when doing something else. Some armchair psychologists told me I had OCD, and when I ended up going to a professional they told me it was definitely not OCD because I lacked several major indicators. They said it was something like “mild generalized anxiety disorder with aspects of persistent anxiety or obsessive worrying of stressors” or something like that.

    In any case, I managed to get better at dealing with stress, although like everyone I do get stressed out from time to time.

    Also, I know plenty of people who have experienced bouts of what might be considered “depression” especially after some traumatic event. Some of my family members were really out of sorts for months after the untimely death of an aunt of mine.

    I'm not so sure that you could really call this mentally ill in the way most people think of it. Certainly it is not an abnormal reaction to a death like that.

  • jaywhite

    The DSM is contaminated by politics especially political correctness as well as the negative effects of big Pharma. The new concept of “spectrum” is a step in the right direction. At times DSM IV is a joke.

  • New Mexico Matt

    Just a thought, but does the fact that 100% of people will experience the common cold between the age of 18 and 32 make the common cold “not a disease”?

    Lots of diseases are a part of normal life. It doesn't make the experience of them trivial.

    I mean if someone is too sad to get out of bed, maybe that's something to think about dealing with whether or not half of all people experience it at some point in their lives. I would also think the fact that clinical depression is the biggest risk factor for suicide would mean that we should think about it seriously and not dismiss it since it is common.

  • Neuroskeptic

    New Mexico Matt: That's a good point re: the common cold, but I think the point about colds is that everyone experiences them and everyone recognises them as a disease.

    Whereas, according to DSM-IV, 50% or more of people experience “mental illness”, but most of them never think of these experiences as illness (and others don't). Which doesn't prove that they're not illnesses, because people can be wrong, but it does mean that it's basically a case of the committees who drew up the DSM-IV vs. “common sense”, and I'm not willing to jettison “common sense” in that match-up.

    Re: “if someone is too sad to get out of bed, maybe that's something to think about dealing with whether or not half of all people experience it at some point in their lives.”

    I agree, but if being too sad to get out of bed in certain circumstances is a normal part of life then it's not clear why it should be dealt with medically. It's common to be extremely sad, often to the point of being unable to function properly following bereavement, but we don't treat grief as an illness. We take it seriously, but not medically. And in doing so we probably deal with it more effectively than if we did decide to treat it as an illness.

  • Socrates

    Dis Muppet just spammed the New Republic too. I found his server and grassed him up to his ISP.

  • Neuroskeptic

    Good work. Spammers triumph when good bloggers do nothing.

  • Scar Symetry

    Great site

  • Uv Uv

    I think someone can have no mental illness and still be in extreme
    emotional agony. In fact, I know they can. Because I was such a person.

    When I was younger, I made two suicide attempts over the course of three months. (Both were overdoses.) The second one, after waking up in the hospital and realizing I was still alive, I tried to sneak out of there to go lie down on the train tracks (no fail method). Two security guards noticed me and had to drag me back to my bed, literally kicking and screaming.

    I’m quite certain I was not suffering from mental illness. I’ve
    read over the diagnostic criteria for depression and other common mental illnesses, and I did not meet them. I just hated my life and hated myself.

    The world is a wounding place. So although I agree that mental illness
    rates are being overestimated, I don’t think that human suffering is
    being overestimated. And just because it isn’t mental illness, doesn’t
    mean it isn’t serious.

    (By the way, I’m now doing great, and have been for over a decade. So don’t worry about me. :) !!)



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About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.


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