Dual Diagnosis: Bipolar Disorder and Addiction

As many as 60% of people diagnosed with Bipolar have some form of addiction as well, and these coexisting conditions are called "Dual Diagnosis." A good portion of people who struggle with Bipolar experience comorbidity, suffering from additional psychiatric illnesses. Some of these diseases include: Anxiety, Obsessive Compulsive Disorder, Borderline Personality, and Schizoaffective Disorder. A disorder is classified as something which interferes with your day to day quality of life, and your ability to function.
Addiction seems to co-occur even more frequently with those already suffering comorbidity. Many times people are undiagnosed or untreated, and they are self medicating their illness(es). Addiction is a disease which takes over a person's life, often changing their personality, ruining relationships, and resulting in legal ramifications. There are strong genetic ties involved, and many families contain multiple addicts. Perhaps these families consist of multiple members suffering from mental illness and that is why such a correlation exists; there is a bit of chicken and egg questioning when addressing addiction and mental illness.
One can become addicted to anything: alcohol, prescription drugs, illegal drugs, over the counter drugs, sex, food, shopping, etc. When one is diagnosed with Dual Diagnosis, and medicating their illness, sometimes the addiction heightens the parts of the disease that feel good like mania/hypomania. When the drug or other stimulant is removed there is a rebound of symptoms. A horrible, sinking depression can settle in and become severe enough to lead to suicidal ideation, parasuicide, or actual suicide. The drug of choice can also make symptoms of Bipolar much worse, from unmotivated depression and leaden paralysis, to rapid cycling and dysphoric mania (mixed state of mania with severe depression which is highly dangerous). The withdrawal of the drug and the resulting crash are what leads the addict to seek the drug again and again, regardless of the consequences. There is simply an obsession in the brain to continue using...as if their very life depends on it.
Dual diagnosis is particularly difficult to treat. Obviously both issues need to be fully addressed in order for recovery to happen, and often a third or fourth disorder also requires treatment. Dual Diagnosis also raises many questions. Did the addiction somehow cause the mood disorder by changing brain chemistry, or awaken a predisposition to psychiatric illness? Is the addiction a result of the mood disorder, or would it be there anyway? If one is self medicating will treating the underlying disorder(s) quell the ravenous beast of addiction, and if not why?
These are just some of the questions raised by this complex phenomenon which impacts so many of us with Bipolar Disorder, and we want the answers.