I've always been low IQ (scored slightly above 80 on an a comprehensive IQ test with a psychiatrist) and it bothered me a lot in the past, that I have difficulties understanding the simplest of things, however in regards to your question, I think it's mostly the other areas of cognition, which noticeably worsened over the years of social isolation, such as short-term memory, creativity and ability to express myself in writing. It's probably also true, that my IQ worsened with time, but I think the other things are more noticeable, I think. Being 17 hours a day for years at a machine, which can simply copy text pieces for me, instead of me having to remember said text for a few seconds, probably did great damage to my short-term memory. My active vocabulary (in my native language and English) has most likely worsened as well, because of me not talking to anyone ever, besides the usual chit-chat on the internet and the few hobby-related words, when discussing hobbies on imageboards for example. I notice the lack of my own creativity not only when doing explicitly creative things, but also with problem-solving (where probably a good point can be made for arguing, that this kind of problem-solving is rather intelligence-related, than with creativity in the usual sense).

It's also easy to fall into a trap of feeling like your cognitive abilities worsen each time you compare yourself to yourself a few months ago, which might be or not be true, but the feeling itself is something that can drive a person into insanity, depression or both. While I think it's true for me, that those things worsened as described above, it's maybe important to keep in mind, what capabilities one had to begin with at a certain point. If you were good at remember information short-term in the past (for example in the realm of a hobby) and now you struggle with it a lot, or you were a creative artist, who drew a bunch of stuff, and now you struggle with that, there might be a case to be made, but it should be measured on what your "output", so to say, is and not a gut feeling of just having becoming stupider than before.

It's true that isolation can easily lead to poverty of stimuli but it doesn't necessary need to be the case, and that is the main reason for "low IQ", not isolation itself.

But just to write my opinion since this is a discussion on an imageboard, I think pursuing IQ/intelligence is kind of a dead end for anyone, so we should better define what we are talking about. I knew plenty of intelligent people who lacked motivation, or some highly creative folks who couldn't even solve simple multiplication problems. In certain situations both of those people can end up with a very sorry execution of their plans. All I'm saying is that IQ is just one dimension of a person, despite the modern understanding that you can treat everything as a problem, so problem-solving must be the ultimate skill to have.

I think the main thing I've lost is energy. I always feel like if I had more of it I could get what I want done but I'm always exhausted and drained.

Another perspective: for many, it's isolation and rejection from the social ingroup that forces them to seek out novel ideas. You can see many people of "high IQ" people that nonetheless don't actually question what they're being told or experience, and thus never exercise those faculties of reasoning. They also can be sufficiently "distracted" by social chitchat so they never bother developing curiosity, never develop the skill of talking to themselves and analyzing things in detail.

As one example, the idea of "rubber duck debugging" in programming always seemed trivially stupid to me, because I couldn't imagine someone _not_ knowing how to think things through by themselves and needing to actually talk out loud to a physical object. Then later on I came to realize that indeed not everyone has this skill, some people (possibly overlapping with extroverts) quite literally cannot introspect and their main mode of deep thinking is external dialogue (with others) as opposed to internal dialogue (with yourself).

So I think it's a wash. Long term depression and isolation without sufficient interesting stimulus to keep you engaged is probably bad. Rejection from the social ingroup is probably beneficial since the skills to cope with loneliness are similar to the skills needed to introspect, which are good for reasoning.

>>30018
>slightly above 80
There's no way your IQ is that, you wouldn't have been able to send a post like the one you sent.

Retake the test elsewhere, your psychiatrist didn't know what they were doing

>>30020
Makes me wonder, you know how people claim to already feel old at 30?
How much of that is purely physiological and how much is psychosomatic (feeling chronically bored, underappreciated, abandoned, disappointed)?
My guess is that the ratio could be as high as 10-90

>>30021
>Long term depression and isolation without sufficient interesting stimulus to keep you engaged is probably bad. Rejection from the social ingroup is probably beneficial since the skills to cope with loneliness are similar to the skills needed to introspect, which are good for reasoning.
I guess, yeah.

But I wonder how many introverts have potentially bright minds that never get the chance to shine, just because they get zero or little appreciation from the rest of the world, which of course is terrible for morale.

Not to mention that sometimes you found out about a new interesting idea, approach or opportunity through your social network specifically. No social network means no fresh air is breathed into your life

>>30024
To me, most of the time claims of being old at 30 appear to be the result of a meme rather originating from an individual's own view, especially with how common and in waves such claims come and go, since the 2010s; I don't really remember that sentiment being quite so popular before.
Then again, this is what I can gleam from the Internet, maybe people do also say that in life, or maybe they don't. Culture can play part into it too - in some places one is still considered a spring chicken by 30.