In High intelligence: A risk factor for psychological and physiological overexcitabilities, a group of academic and industry neuroscientists survey a self-selected group of 3,715 MENSA members about their mental health history and find a correlation between high IQ and clinical anxiety and depression disorders, an effect they attribute to "overexitabilities" -- "the same heightened awareness that inspires an intellectually gifted artist to create can also potentially drive that same individual to withdraw into a deep depression."
It's an interesting study and it has a good sample size, but there are some big caveats here.
First, it's not clear that IQ measures intelligence. People from higher incomes tend to score higher on IQ tests, and you can "study" for an IQ test, which suggests that what's being measured is a set of acquired skills and knowledge, not the capacity to acquire those skills and knowledge (your "quotient").
Second, joining MENSA may be an indicator of some underlying insecurity about your intellect or place in the world, reflecting a predisposition to depression or anxiety, so they may have instead discovered that MENSA membership (not high IQ) is correlated with mental illness.
Third, the sample self-selected from an email blast to the MENSA membership, so again, perhaps they've found a link between a willingness to disclose mental illness to researchers and high IQ, or MENSA membership, or whatever.
Finally, in the US, access to medical care and thus formal mental health diagnosis is strongly correlated with income. That means that you're more likely to have a professional affirm that your distress is caused by a clinical disorder if you're wealthy than if you're poor. High IQ correlates with wealth, and the wealth distribution in the study draws from disproportionately high-income subjects ("41.7% earned over $100,000; 16.9% earned between $76,000 and $100,000; 20.1% earned between $51,000 and $75,000; 14.9% earned between $26,000 and $50,000; and 3.9% earned less than $25,000") so maybe they've found a correlation between wealth and mental health diagnoses.
The part of this that resonates for me is the relationship between introspection and depression/anxiety. The depressive and anxious episodes I've experienced have been characterized by high levels of introspection ("Why did I do that? Why did they do that? What if I screwed this up?"), and, ironically, so did my way out of it -- Cognitive Behavioral Therapy, which deploys systematic introspection to help navigate these storms.
I think that introspection and intelligence (whatever intelligence is) are also probably linked. The best artists and thinkers I know spend a lot of time thinking and thinking about thinking, so this study feels like it should be true. But as they say, "more research is needed" -- I'd love to see a version of this that did better sampling and a more robust definition of "intelligence."
High intelligence is touted as being predictive of positive outcomes including educational success and income level. However, little is known about the difficulties experienced among this population. Specifically, those with a high intellectual capacity (hyper brain) possess overexcitabilities in various domains that may predispose them to certain psychological disorders as well as physiological conditions involving elevated sensory, and altered immune and inflammatory responses (hyper body). The present study surveyed members of American Mensa, Ltd. (n = 3715) in order to explore psychoneuroimmunological (PNI) processes among those at or above the 98th percentile of intelligence. Participants were asked to self-report prevalence of both diagnosed and/or suspected mood and anxiety disorders, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and physiological diseases that include environmental and food allergies, asthma, and autoimmune disease. High statistical significance and a remarkably high relative risk ratio of diagnoses for all examined conditions were confirmed among the Mensa group 2015 data when compared to the national average statistics. This implicates high IQ as being a potential risk factor for affective disorders, ADHD, ASD, and for increased incidence of disease related to immune dysregulation. Preliminary findings strongly support a hyper brain/hyper body association which may have substantial individual and societal implications and warrants further investigation to best identify and serve this at-risk population.
High intelligence: A risk factor for psychological and physiological overexcitabilities [Ruth I.Karpinski, Audrey M.Kinase Kolb, Nicole A.Tetreault and Thomas B.Borowski/Elsevier Intelligence]
(Image: Gaetan Lee, CC-BY)