How can you tell if a person has bipolar disorder?

Evaluation. A diagnosis of bipolar disorder is made mostly due to the presence of specific symptoms or characteristics. The diagnosis needs to be made by a qualified mental health professional. Sometimes, psychological tests can be helpful in distinguishing bipolar disorder from other problems.
History. Symptoms include mania-racing thoughts, increased goal directed activities, impulsive actions like gambling, excessive spending or excessive sex, using drugs or alcohol, decreased need for sleep, sometimes behaviors are so severe a person ends up in the hospital or jail. If the symptoms are not caused by drug use and last for more than a week, it may be bipolar disorder. Depression also occurs.