A doctor performs a complete psychological and physical evaluation along with an interview to determine whether a person has depression, notes MedicineNet. Because the side effects of some medications and medical conditions can include some of the symptoms of depression, all three elements are necessary to avoid false diagnosis.
The patient history includes a discussion of the duration of the symptoms that the person shows. Understanding when the symptoms began, whether they have been consistent or intermittent, and how severe they have been are all vital parts of the process. Any instances involving prior treatment are important, as are the outcomes of those prior treatments, according to MedicineNet.
As part of the interview, a doctor generally asks about drug and alcohol use and whether or not the patient has considered suicide. Because genetics play a role in many medical conditions, the doctor also asks about family members who may have suffered from depression as well as their treatment histories, MedicineNet reports.
Another part of the evaluation includes an examination of mental state to see if the illness has affected memory, thought patterns or speech. No lab tests or blood tests can diagnose psychiatric orders as of March 2015, but imaging tests can be valuable to determine whether or not physical conditions are causing some of the symptoms, states MedicineNet.