how to encourage a spouse or partner to resume treatment

My husband, like many of the spouses here, has depression and anxiety along with ADHD.  As far as I know, he's not taking any medication now ("they don't help," his words).  He's not in therapy.  I think he seemed better when on meds and in therapy.  Tonight, the death of Robin Williams is weighing heavily on me.  Any ideas for encouraging a person with untreated mental health issues to get back into treatment?  Thank you.