It either is the "second leading cause of disability and mortality" or it isn't, there's nothing to believe. I very much agree with GP that the claim is completely unsupported.

I found the study that the article bases this on[1]. It doesn't make this claim and instead associates a higher mortality rate to sufferers of all mental disorders, 67% of which are deaths by natural causes. That these natural causes are directly associated with the mental disorder isn't even something the study says. Anxiety is just one of the many disorders analyzed.

This is similar to attributing a lower life expectancy to all people with endocrine diseases (e.g. diabetes) and later saying hyperthyroidism (another endocrine disease) is the sole cause of death in that group.

- [1]: https://jamanetwork.com/journals/jamapsychiatry/fullarticle/...

There is space to suspend your belief/disbelief before you look it up and entertain an idea as plausible to consider what it might say about the discussion at hand. This doesn't mean blindly believing make believe, rather it means deferring coming to a conclusion, to quote the site guidelines, to converse curiously. Of course you can look it up and resolve it after the fact, but that doesn't mean the rest of the surrounding context can't be interesting without the resolution.