...Go hand in hand.
I've certainly realized in the last 18 months, that when you are living with chronic pain, depression certainly takes hold a lot quicker or more often, or for a lot longer!
I feel the worse the pain gets, the worse the depression gets, mainly because the pain restricts my activities a lot...
But it's kinda ironic really, that the same anti-depressants we use for our depression are also used these days, for neurological pain. (I have Occipital Neuralgia)
But it's a pity I can't find the right med which doesn't have so many bad side-effects, and doesn't make my other medical conditions worse!
I'm sure there are many others out there suffering with chronic pain, and maybe battling depression as well...

~Jaime~