Smart People Say They’re Less Depressed

By Neuroskeptic | January 12, 2013 9:26 am

The questionable validity of self-report measures in psychiatry has been the topic of a few recent posts here at Neuroskeptic.

Now an interesting new study looks at the question in issue from a new angle, asking: what kind of people report feeling more or less depressed? Korean researchers Kim and colleagues found that intelligence and personality variables were both linked to the tendency to self-rate depression more severely.

The study involved 100 patients who’d previously suffered from an episode of depression or mania and who, according to their psychiatrist, had now recovered and were back to normal. Kim et al looked to see what the patient thought about their mood, by getting them to complete the Beck Depression Inventory (BDI) self-report questionnaire.

This was compared to the clinican-administered HAMD scale (another Neuroskeptic favourite) which is meant to be independent of self report.

It turns out that the BDI and HAMD scores were only weakly correlated – with a coefficient of just r=0.32. That’s really not very good considering that, in theory, they both measure the same thing: ‘depression’. Many people reported being considerably depressed when their clinicians rated them as fine.

But more interestingly, certain characteristics of the patients were correlated with their self-report/clinician-rating discrepancy. Specifically, patients with a lower IQ, who were more impulsive, and less conscientious, tended to self-report more severe depression.

Now, the uncharitable interpretation of these people is that they were just too sloppy to complete the form properly… the uncharitable interpretation of the psychiatrists is that it’s their fault for underestimating depression in people less inclined to express themselves in ‘the right way’. There’s no way to know.

Either way, it’s a serious problem because it shows that self-report and observer-report measures of depression aren’t just poorly correlated, they’re actually measuring different things for different people.

It could be even worse than it appears because the HAMD, although supposedly not a self-report measure, does in fact heavily rely on the patient’s cooperation. So a 100% clinician-rated scale might be even further removed from self-report.

ResearchBlogging.orgKim EY, Hwang SS, Lee NY, Kim SH, Lee HJ, Kim YS, and Ahn YM (2012). Intelligence, temperament, and personality are related to over- or under-reporting of affective symptoms by patients with euthymic mood disorder. Journal of affective disorders PMID: 23270973

  • http://petrossa.me/ petrossa.me

    Counter intuitive result. The smarter one is, the more acutely one is aware of the fact homo sapiens is one of those evolutionary branches to go extinct sooner rather than later.

    And if you are into that stuff, the global balance of welfare/misery being in the 10/90 without any realistic room for
    improvement.

    Both reasons enough to be at least less than happy.

  • Anonymous

    Since the patients were selected by clinicians' judgement of their recovery, it is to be expected that the correlation between BDI and HAMD would be low. The selection results in lowered variability of HAMD scores and that in turn is bound to lower the correlation between BDI and HAMD.

  • http://www.blogger.com/profile/16203083806436919715 Bernard Carroll

    We have known for a long time that self ratings of depression are not completely reliable. There are data from 40 years ago comparing the Hamilton scale completed by physicians and the self-rated Zung scale (see PubMed ID 4688625). We looked at patients in general practices, in a day hospital, and in an inpatient unit. The pragmatic severity gradient went up from GP to DH to IP, and that was verified by Hamilton scores. On the self ratings, however, there was no significant difference across the three treatment settings. Most likely this happened because the self rating scale treated persistence of symptoms as equivalent to severity of symptoms. This simplistic equivocation is still happening, even in current NIMH-supported efforts to develop new scales (see PubMed ID 23117634). That misstep creates serious problems in multi-center research studies – you can never be confident that the patients in site A really are equivalent to those at site B.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Anonymous: Mmmm. True. And actually that might explain the IQ and personality results; if we assume that impulsive people with low IQ are just sloppy and give more variable noisy answers, then the answers will tend to be higher, rather than lower, assuming the 'real' BDI scores are all low, because they've recovered.

  • http://theboostbook.com Douglas Heingartner

    Links to some other studies on the (lack of a) IQ/happiness correlation at
    http://theboostbook.com/2013/01/link-between-intelligence-and-happiness/

  • http://www.blogger.com/profile/13304729731231255545 Torbjörn Larsson, OM

    @petrossa: That doesn't seem very smart, seeing how we are evolving faster than ever before. (Cf John Hawks et al.) We will likely evolve to something else rather than the population goes extinct.

    That 80/20 observation is a relative measure, society can always be improved.

    And it is part of what we know now works to make societies not dysfunctional (free trade, democracy, social medicine). As for democracy it may be the best alternative among options no one particularly like, but we don't know for sure.

  • http://www.blogger.com/profile/05947354805110334594 Nettie Collis

    There are many reasons why depression is under reported by the patient. I have under reported myself on these measures (I work in the field and know about them)1) simply because I do not wish the time I have to see my psychiatrist to be cranked up. 2) Sometimes I do not want him to know just how bad things have got. 3) I feel ashamed for feeling this way and 4) I have learned there is little can be done but to ride it out. Antidepressants don't work well for me.

    I am not sure, but I suspect my IQ is not low!

    I have used these measures in the community myself and to be honest I have sometimes been stunned and surprised by the answers people have given. Those people I thought severely depressed reported not being so and visa versa. Given that I often scew the answers myself I don't why I should be surprised when other people do!

  • joe

    Perhaps intelligent people are more introspective and attribute specific episodes of unhappiness to particular causes rather than some non-specific vague state of being, whereas less intelligent people are less introspective and do not really understand (or do not think they understand –important difference–) the cause of their sorrows.

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No brain. No gain.

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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