"Intelligence research most often focuses on the flashes of lightning seen in this rare population, however in order to serve this group of individuals fully, we must not neglect to acknowledge the rumbles of thunder that follow in the wake of their brilliance."
There was something rather poetic in the above sentence concluding the paper by Ruth Karpinski and colleagues  talking about "high IQ [intelligence quotient] as being a potential risk factor for affective disorders, ADHD [attention-deficit hyperactivity disorder], ASD [autism spectrum disorder], and for increased incidence of disease related to immune dysregulation." The idea being that "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)."
I have to say that I was/am slightly unimpressed with the terms 'hyper brain' and 'hyper body' - it sounds like something from a movie I watched a while back - but am genuinely interested in the possibility of an intersection between the brain and other body functions particularly in the context of risk for specific health-related labels.
So, examining some 3700 members - "the majority of participants were older, male, and European American" - of American Mensa, Ltd. researchers sifted through responses to various questions about psychological and somatic health answered by participants. The on-line questionnaire used as the self-report tool (yes, self-report tool) included items covering both "diagnosed and suspected" in terms of various diagnoses, and results were compared against national average data covering quite a bit of clinical ground.
Results: an interesting pattern of both suspected and diagnosed comorbidities emerged from the high IQers [self-report] data. I've already quoted the authors in terms of an over-representation of autism, ADHD and affective disorders (mood and anxiety disorders). The degree of over-representation of such diagnoses was not insignificant: for autism for example "When comparing diagnosed patients, there was 1.2 times the risk within the high intelligence group compared with national averages (a 20% increase). However, an additional 5.1% suspected that they should be diagnosed with ASD, for a total combined risk of 6.3 times the national average, an increase of 530%." This perhaps ties into other independent research too (see here) bearing in mind that diagnosing autism is probably best left to the professionals (see here).
But alongside, there was also a somatic angle to consider: for 'environmental' allergies for example we are told that: "Overall, there was 3.13 times the risk of being diagnosed with an environmental allergy, an increase of 213%, for those with high cognitive ability. When included self-diagnoses, there was 4.33 times the risk, for an increase of 333%." Asthma and autoimmune diseases also registered. The same caveat about caution in self-report and self-diagnosing coming into play too.
There is quite a bit of data to absorb in the Karpinski paper and I would encourage readers to plough through it. One detail that particularly struck me in their "Hyper Brain/Hyper Body: a theoretical framework" diagram was where the authors chose to place autism - in the hyperbody side of things - and their comments: "that one such plausible genetic component to consider is that of high IQ which may be responsible for a hyper physiological response to these insults and a resulting development of ASD." I can't say if they're right or wrong about this but certainly the connections made between [some] autism and things like neuroinflammation (see here) and immune function (see here) are not to be forgotten or glossed over. More so when one considers what something like [acute] inflammation *might* be able to do in the context of psychological processes (see here).
So what implications do the Karpinski results have for clinical practice for example? Again, harking back to the opening sentence, an appreciation that with great intellectual power may come the potential for enhanced health risks is worthwhile reflecting on and what it means for preferential screening for example, alongside healthcare planning. I say this bearing in mind that correlation and causation are not one and the same, and also that the reliance on self-report used in the Karpinski study is, by no means, to be put to one side. If one however assumes that a measure like IQ has a significant genetic loading behind it, one might also speculate that the same genes (or expression of genes) governing any such association might also have the ability to affect parameters such as autistic and/or ADHD traits, the presence of depression and anxiety and also immune function in relation to things like 'environmental' allergies or autoimmune conditions. In the same way that autism genes are probably not just 'genes for autism' (see here) so a wider picture seemingly emerges with IQ potentially in mind...
To close, and without trying to trivialise the subject matter today, I wonder if people like Stan Lee and other 'Marvel'ous folk had it right when they portray great power often being balanced with a seeming lack of power?
 Karpinski RI. et al. High intelligence: A risk factor for psychological and physiological overexcitabilities. Intelligence. 2017. Oct 8.