Major Depressive Disorder and Substance Use Disorders
Some disorders are so closely associated with bipolar disorder that at times they seem to be inseparable. However, this is a superficial impression. Health risks like major depressive disorder (MDD) and substance use disorders are distinct problems with symptoms that may look like bipolar disorder at times, but should not be confused with it.
Major Depressive Disorder
MDD has the same symptoms seen in bipolar depressive episodes. The defining difference between the two mood disorders lies in the absence of past manic, hypomanic, or mixed episodes in MDD. Without a clinical test, the only way to tell the difference is to determine whether there is a history of such episodes. This is extremely difficult when the first sign of bipolar disorder is a depressive episode, something that happens in more than half the cases. Obviously, it is necessary to closely follow someone to see if they eventually experience mania in order to distinguish these two major mood disorders.
Recreational drug use and abuse often results in symptoms similar to those of bipolar disorder. Recreational drugs fall into three main categories: stimulants, including powder cocaine, crack cocaine, and amphetamines; depressants, such as alcohol, tranquilizers, and barbiturates; and hallucinogens, which can be considered minor, like marijuana, or major, like LSD.
Substance Use Disorders
Many people with bipolar disorder — between 40 percent and 60 percent by some estimates — have a long-term substance use disorder as well. Usually, the drug of choice is alcohol, a depressant, but stimulants such as cocaine and amphetamines are also abused. Besides the health risks that come with substance abuse, alcohol and illegal substances can produce symptoms very similar to those of bipolar disorder, including depression and mixed and manic states. If someone's extreme moods end when the substance use ends, it suggests that the drugs and not bipolar disorder might be the cause. But it isn't easy to tell if someone who has stopped drinking, for example, is depressed because they gave up alcohol — a common reaction — or if they are experiencing a bipolar depressive episode. Stimulants mimic manic states by promoting risky and impulsive behaviors, reducing the need for sleep, and increasing the need for social and other stimulation.
The flip side of the association between bipolar disorder and substance use disorders is the tendency of mania to reduce limits of self-control, which frequently leads to use of illegal drugs. This can make it very difficult to determine quickly if someone has substance use disorder, major depressive disorder, bipolar disorder, or a combination.