As far as I am aware, radical life extension is not considered one of the focuses of Effective Altruism. 80,000 Hours Problem Profiles page doesn't mention it; the Wikipedia and AIs say it isn't. The most recent mention of life extension on this forum I found is this request for questions as a preparation for the interview to evaluate the cause Life Extension Advocacy Foundation (LEAF). No questions were asked and I couldn't find the interview; it seems that there just wasn't any interest in the topic.
But why?
About 166,000 people die in the world each day, or 60 million per year, most of them from age-related disease. If we could postpone that for 1 year, we would save tens of millions of QALYs, or raise world GDP by 1-2%, in economic terms. This should make causes focused on extending lives worthy of consideration, in my view; wouldn't it?
Then why can I see no sign that radical life extension was even considered as a field of Effective Altruism? The AI told me that radical life extension is speculative, but so is preventing risks from AI, isn't it?
Is it because the interests of the originators of EA movement lie elsewhere (and the movement followed)?
Radical life extension is IMO a big part of the rationalist worldview, if not the EA movement. (Although recent progress in AI has taken attention away from anti-aging, on the grounds that if we get AI alignment wrong, we're all dead, and if we get alignment right, the superintelligent AI will easily solve aging for us.)
One of the problems with radical life extension as an EA cause area is that it seems like other people ought to be rationally self-interested in funding anti-aging research, so it's not clear why EA should foot the bill:
Health interventions in the world's poorest countries -- a lot of the leverage comes from the fact that poor people often don't have the resources or knowledge to help themselves
Animal welfare & longtermism -- animals obviously have about ~0 ability to advocate for themselves. Ditto for unborn far-future generations of human civilization.
Anti-aging -- sure, there is a pretty significant collective-action problem (I might pay for anti-aging research because I personally don't want to die, but then the benefits are diffused around to all humanity), but still, wouldn't there be plenty of especially rich people willing to pay the $$$ to do the anti-aging research?? Yes, indeed, this is what we see:
Personally, I cheer these billionares on, I think they're doing a great thing, and I think people in general ought to wise up about the badness of death and aging (it would be great if millions more people had read "The Fable of the Dragon-Tyrant"!) and support more anti-aging research through government-funded health agencies. HOWEVER, even with all that enthusiasm... I don't think it's really a great fit for an EA cause, since so many other people have a self-interested incentive to fund this stuff.
I'd also note that hundreds of billions of dollars are spent on biomedical research generally each year. While most of this isn't targeted at anti-aging specifically, there will be a fair amount of spillover that benefits anti-aging research, in terms of increased understanding of genes, proteins, cell biology etc.