Based on the article: Prevalence, chronicity, burden and borders of bipolar disorder by Fagiolini, A et.al. Journal of affective disorders 148 (2013) 161-169
The traditional defining feature of bipolar disorder has always been the prevalence of a manic or hypomanic episode alternating or occuring cocurrently with a depressive episode.
Depression is a relatively easy condition to diagnose where as bipolar disorder poses more challenges due to a lack of information and the need of historical input together with the evaluation of current symptoms. This is the main reason behind many people suffering from bipolar disorder (especially type 2) get misdiagnosed with unipolar depression.
In a study conducted in a psychiatric setting, of the 203 patients presenting with a mojar depressive episode, only 103 were found to have unipolar depression, the rest were diagnosed with Bipolar disorder type 1 or 2. To add to this, another study have found that between 30 and 40% of people with bipolar disorder were previously misdiagnosed as having unipolar depression. The BRIDGE study found that 16% of the 5693 participants presenting with a major depressive episode met the criteria for bipolar 1 disorder and 47% met the bipolar specifier criteria.
Unipolar depression is not the only mental illness people get wrongfully diagnosed with, some have been diagnosed as schizophrenic, suffering from anxiety disorder and having borderline personality disorder
To me, it is clear that a lot of work still needs to be done to differentiate more clearly between the different psychiatric illnesses. This is a pressing matter since it determines the path of treatment and when just considering medication, misdiagnosis can have a very negative impact on the outcome of the treatment. An example of this is the administration of anti-depressants to people suffering from bipolar disorder leading to unstable mood and rapid cycling.
If you are in any way unsure of whether you have been correctly diagnosed, I urge you to go for a second opinion even if it is only for your own peace of mind. I got a second and third opinion before I accepted my diagnosis. I’ve also been misdiagnosed firstly with major depression and then later it was atypical depression and then it was borderline personality disorder. This caused a lot of emotional distress and confusion and caused me to distrust psychiatrists. Luckily my faith was restored by a kind, wise, super intelligent and knowledgeable doctor, who got me stable and on a combo of meds that work for me. Unfortunately we don’t all have a happy ending, at least not yet. :) If you were previously misdiagnosed please tell us your story in the comments section. Maybe someone can relate to what you went through and get help to make sure they are being treated for the right illness.