I just finished Fatal Deduction by Gayle Roper that definitely included elements of bipolar disorder and gambling addictions. Both disorders made up subplots in the story, as the hero's ex-wife had bipolar disorder (and from the indications in the novel, she was a rapid-cycler) and the heroine's sister was involved with a loan shark who made his money feeding off others' gambling addictions.
I just picked up Sharon Hinck's Stepping Into Sunlight, which looks like it will include some elements of mental disturbance. The heroine witnesses a horrific crime, which likely will result in post-traumatic stress or some other depression or anxiety disorder, that renders her wanting to hide away in her home and not take care of everyday affairs. The twist in Hinck's story seems to be how the heroine plans to overcome this...by doing one good thing for someone else every day. So I'm eager to start in on her book, as it likely will help me with my own current WIP.