While the genetic link between bipolar disorder and substance abuse remains inconclusive, Cheryl Murphy, of Las Vegas, is sure that both burdens run in her family. Murphy, 62, once lost custody of three of her four children and has attempted suicide five times. Now sober for 25 years, she is functioning well. She is also raising her 3-year-old great-grandson because her granddaughter, who also has bipolar disorder, abuses drugs. Murphy's great-grandson, too, was recently diagnosed with bipolar disorder.
A dearth of research
It's been difficult to study the link between bipolar disorder and substance abuse because, traditionally, research on bipolar patients has screened out substance abusers, and vice versa, says Dr. Tolliver. He and other experts would like to see more research into treating patients with both problems; about 20% of people seeking treatment for a mood disorder are also substance abusers. In a 2004 study, 41% of alcohol abusers and 61% of drug abusers who sought treatment for their problem were also found to have a mood disorder such as bipolar.