It’s possible, if the diagnostic person isn't sure of what they are doing.
Bipolar disorder is not a difficult illness to diagnose in adults. It is a rather popular illness these days and I would assume there are people who jump to the conclusion that they have bipolar, but it can be easily diagnosed correctly by an experienced health care professional who asks the right questions.
Here’s what makes the diagnosis easy: There is one and only one criterion for the diagnosis of bipolar. A person must have had an obvious manic episode.
For many years, until bipolar was more widely talked about, the misdiagnosis was actually a depression diagnosis when it should have been bipolar. Thus, people with bipolar disorder got the wrong diagnosis of depression!
What About Genetics?
Genetics are also a good indicator of a correct diagnosis: In all of my years working in the bipolar disorder field, I have rarely met someone with bipolar who didn’t have mood disorders in the family.
If a person is diagnosed with bipolar and feels it’s incorrect, they can look into the past for signs of relatives with either depression or bipolar.
For example: My grandfather had four wives, drank too much and kept starting businesses that didn’t work. My mother was mildly to strongly depressed my entire childhood. My brother went in for depression treatment and after a year of anti depressants and ADD meds had his first manic episode and now has bipolar.
Caveat: The biggest reason for a 'wrong diagnosis' is that it may not be a complete diagnosis. Bipolar can be combined with schizophrenia psychosis (called schizoaffective disorder) and it’s VERY common to see bipolar with personality disorders such as borderline, antisocial or narcissistic. All of these can greatly complicate a diagnosis.
What about the Childhood Diagnosis?
There are DEFINITELY incorrect diagnoses here. The diagnosis of bipolar in children has gone up 40% in the past ten years. Bipolar became a catch all diagnosis for kids with seemingly similar symptoms to bipolar, but it turns out to be far more complicated than a straight bipolar disorder diagnosis.
(There are other questions and answers on this site regarding the childhood bipolar disorder diagnosis.)
If you received what you feel is the wrong diagnosis, I suggest you read the bipolar disorder questions on this site and then see a health care professional who really knows how to diagnose!