Clinical depression is a serious ailment - so much so that you have to wonder about the wisdom of putting yourself up for a political office representing other people while you're also dealing with your own illness.
Ludlum says he's been dealing with anxiety and depression for a while, didn't see any disclosure from him at the election 4 months ago. He'll return to work when he can give the commitment the job demands.
WA voters might have been interested to hear of the issues that stop you giving the commitment you volunteered to deliver at the election.
Elected politicians aren't there just for themselves. They take on a job representing the interests of other people. That places a higher burden of responsibility than most other jobs. If you can't find it in yourself to give the commitment the job demands perhaps resignation is the more responsible course - allowing someone who can commit themselves to representing the interests of other people.