Saturday, January 21, 2012

Intelligence and depression

OneSTDV wonders:
There's some controversy over whether higher intelligence and depression correspond. From reading the "intellectual" sphere, generally defined as people who engage in self-analysis, one would surely conclude that such a correlation exists.
Arriving at this conclusion, unfortunately, demonstrates how problematic relying on a few anecdotal data points to arrive at generalized conceptions often is. On top of a prohibitively small sample size, selection bias is also at work here. Robert Lindsay summarizes the relevant scientific literature as follows:
Careful studies have shown that the high IQ basket case is a myth. Studies of very high IQ types have found that in general, as IQ rises, so does mental health. Why this is is not known.
The GSS shows that the least intelligent are the most likely to view life as being devoid of meaning. It's not difficult to imagine why this is the case, whether one employs a Maslow-esque hierarchy of needs where those of modest intelligence tend to be found near the base and the more intelligent closer to the top, or one simply realizes that those on the left end of the bell curve are generally incapable of thinking abstractly.

OneSTDV contrasts "cloudy skies" depression (which might be defined as feeling blue) from the sort of existential depression that a person is susceptible to if he dwells too much on the "relative scale of humanity in the context of our universe". We've seen evidence that argues against the assertion that existential depression and intelligence are correlated. Propitiously, the GSS also provides an item to gauge the more mundane "cloudy skies" depression. Since 2002, it has asked respondents how often they've experienced mental health problems (which include, but are not limited to, depression) over the last 30 day period. The averages (means), by intelligence grouping* (n = 2,537):

Intelligence
Blue days
Real Dumbs
3.7
Pretty Dumbs
3.7
Normals
4.1
Pretty Smarts
3.4
Really Smarts
3.3

Not much variance in the averages here. About the only thing that might be suggested is that higher intelligence may provide a bit of resistance to melancholy.

GSS variables used: WORDSUM(0-3)(4-5)(6)(7-8)(9-10), MNTLHLTH, NIHILISM

* Respondents are broken up into five categories that come to roughly resemble a normal distribution; Really Smarts (wordsum score of 9-10, comprising 13% of the population), Pretty Smarts (7-8, 26%), Normals (6, 22%), Pretty Dumbs (4-5, 27%), and Real Dumbs (0-3, 12%)

9 comments:

gwern said...

> Robert Lindsay summarizes the relevant scientific literature as follows:

You hardly summarize when you don't include any citations...

HEL said...

I've heard a fair amount of discussion about this over the years in the HBD realm. I don't pretend to have any real answers, but I think we have a problem with definitions.

I'm a pretty damn smart guy, I believe, no genius but clever enough, and I don't consider the top 13% of the population to be "really smart." I'd estimate, oh, I dunno, that 75% of the public are abject morons, another 15% are passable, 10% qualify as at least smart-ish with a 2% subset of that last group being really smart. From my experience with other people of approximately my intelligence, this is a pretty common view, though some might state it in a more generous manner.

When you discuss intelligence relativistically you aren't really addressing the colloquial definition of "highly intelligent" that exists among the highly intelligent themselves. I tend to suspect that mental health issues do decrease with IQ up to a very extreme uppper region, at which point they begin to tick up again. This is a small enough fraction of the populace, though, that it doesn't necessarily come through in a more general study.

Anonymous said...

I think religion is a confounding variable.

On the one hand, the highly intelligent have a much easier life, more money, better health, easier work and so forth.

On the other hand, many intelligent people turn away from religious faith, making them less happy. Happiness and religiosity are strongly correlated after all.

If you are fairly intelligent and are able to maintain religiosity, you may be doing pretty well for yourself.

Audacious Epigone said...

Gwern,

Fair enough, but he's well read and that's the impression I've ended up with as well, so I'm comfortable quoting him here.

HEL,

Yeah, that could potentially be the case, although I'm not aware of any particular reason to think it is so (beyond the fact that it sounds plausible). I don't think that's the impression OneSTDV has, though, which is why I posted this.

Anon,

Yes, actively religious folks tend to be less nihilistic than the non-religious are, while intelligence and nihilism trend in opposite directions.

silly girl said...

"with a 2% subset of that last group being really smart."

Hey thanks for making that 2% instead of 1%. That way I get to be one of the dumbest smart people instead of far and away the smartest of the dummies.

Did you do that just so you have some more chicks in there? I hope so, and I appreciate it. :-)

Anonymous said...

"I dunno, that 75% of the public are abject morons."

And of that 75% quite a few would be your family members and my family members. Nice. The 'colloquial definition' of moron might also apply to you.

R. Jones said...

0.4 correlation with suicide and national IQ. 0.1 correlation with suicide and GDP. Smart nations are more depressed. Smart individuals, not so much.

http://www.china-sds.org/kcxfzbg/addinfomanage/lwwk/data/kcx657.pdf

Audacious Epigone said...

R. Jones,

Thanks. I wonder what the correlation between suicide rate and TFR is? Have those numbers been run? If not, I'll run them.

Meng Hu said...

Perhaps you already know, but this recent review of IQ correlates is very interesting.
http://menghusblog.files.wordpress.com/2012/02/national-iqs-a-review-of-their-educational-cognitive-economic-political-demographic-sociological-epidemiological-geographic-and-climatic-correlates.pdf

See table 13 and 17 (happiness, life satisfaction etc).