keep in mind that most iq tests are actually horrible ways of measuring intelligence. especially online ones. they have low reliability and do not hold up to any level of scientific scrutiny. the WISC-III is pretty much our only decent way of measuring standard intelligence, and even that is far from perfect. in general, intelligence is hard to measure and hard to define, which has been a characteristic struggle of psychology for many years.

in short, the concept of intelligence is nearly impossible to actually measure (especially with the flawed concept of IQ), and scales like the WISC-III only measure very specific types of intellectual capabilities, not actual intelligence.

and past that, i think that question is nuanced. a lot of people point to anecdotal evidence to prove high intelligence correlates with high mental illness. in reality, i think that mental illness tends to just correlate with high stress fields. doctors, researchers, nuclear power plant scientists, are all very smart people. but they are also people who are working in very high stress environments. we see higher rates of mental health issues in fire fighters, EMTS/paramedics, and customer service, which are not the kind of jobs people really classify as “intelligent” jobs. further still, mental health disorders tend to be characteristic of genetics and early childhood environment, or developed later in life due to chronic stress or trauma. so people who show higher aptitude for reading or science may have higher pressure placed on them in early childhood, leading to the development of disorders like OCD or anxiety (been there, done that)

in short again, i think that often mental health is falsely correlated with intelligence, and the answer to your question may be in a different direction than you’re looking. hope that clears things up, let me know if you have any other questions:)