Radiohead did not use 'the bends' as a metaphor for drugs - it was (quite an obvious, i thought) metaphor for their fast rise to the top and how it drove them crazy that everyone suddenly loved them for this one song and their frustration i guess at fake people who just wanted to be with them for their fame.
This is also implied in the EP My Iron Lung (Iron Lung being a metaphor for the song "Creep" incase you didn't catch that).
The words are coming out all weird
Where are you now when I need you?
And who are my real friends?
Have they all got the bends?