I suspect a form of survivorship bias is contributing to these results.
Less-high-IQ people with the same disorders may never be diagnosed with these sorts of (often subtle & subjective) mood/anxiety/learning/chronic-immune disorders.
Perhaps, even, less-high-IQ people are more likely to literally perish before such diagnoses show up in national averages.
(And that's before considering the filter that many others have already mentioned: that only some, potentially-unrepresentative high-IQ people find the idea of joining MENSA appealing.)
Less-high-IQ people with the same disorders may never be diagnosed with these sorts of (often subtle & subjective) mood/anxiety/learning/chronic-immune disorders.
Perhaps, even, less-high-IQ people are more likely to literally perish before such diagnoses show up in national averages.
(And that's before considering the filter that many others have already mentioned: that only some, potentially-unrepresentative high-IQ people find the idea of joining MENSA appealing.)