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%)