|Unfortunately prevalence of addictive behaviours and risky lifestyle choices is much greater among those with bipolar disorder. Studies have shown that 50% of people with bipolar struggle with some kind of addiction, usually a combination of tobacco with alcohol or substance abuse.
Look at it this way. Most "normal" people achieve in life with one goal in mind - the pursuit of happiness. They work hard so they can own that nice car, which generally brings a feeling of happiness at least for a little while. Being awarded a position at work, or being given the respect of your peers ... that brings happiness. Bringing a child into your life for most people brings feelings of joy.
People with bipolar experience no such thing. They are incredibly lucky if their mood EVER represents their standing in life, or what's going on around them. They can be feeling miserable and suicidal when they've just fathered their first child, or been given a promotion at work, or at the best holiday they've experienced. Some may even feel elated or manic when a close friend has passed away.
This is where addiction comes into the picture. An untreated bipolar patient feels there is no constancy or stability in their moods, so they reach desperately for anything to self medicate the ups and downs. They then realise that when they take X drug, or drink, they feel Y. ie bipolar patient + alcohol & / or drugs = feeling high. It's the only constant equation in an otherwise chaotic moody whirlwind of untreated bipolar. Taking drugs or drinking alcohol or smoking cigarettes affords the only sense of control over their feelings.
Most people assume that treatment will resolve this problem. However, treatment for bipolar is far from an exact science. Mood stabilising medications can reduce the severity of the cycling, but the patient's mood is STILL cycling underneath - their mood still doesn't represent the state of their life, or what's going on around them. They're very lucky if their emotional compass bears any semblance to the reality of their life. If they manage to take enough medication to eradicate the cycling completely, they may very well find other areas of their cognition take a hit as well. Lithium toxicity offers an interesting insight into the state of bipolar treatment. The main symptom of toxicity is "confusion / stupor". People prescribed lithium are taking barely sub-toxic doses, but it is this same effect of "confusion / stupor" that affords lithium's mood-stabilising / therapeutic effect. The patient's cognition is fogged out such that they take less notice of their moods. That is what mood-stabilisers are. Psychiatry is still in the dark ages with bipolar, and arguably mental illness as a whole.
There's a reason bipolar is the biggest burden on welfare out of all mental illnesses affords an interesting insight into human nature, and the importance of the individual pursuit of happiness on maintaining a progressive and functional society. It seems once the internal emotional compass is thrown off its axis, there becomes little point in achieving anything, or directing one's energy in any positive direction. A treated bipolar patient may only manage to calm the storm enough to point themselves to where society expects they should be going.