People with a long history of depression and who had been in the hospital for their depression were more likely to develop bipolar disorder.
"Talk to your psychiatrist about all your symptoms."
The study, led by Dominika Dudek, MD, Adult Psychiatry Department at University Hospital in Cracow, Poland, looked at the charts of 122 people with depression.
They looked to see how many patients had a change in diagnosis from depression to bipolar disorder. The researchers looked for the age that depression started and the time between depression diagnosis and bipolar diagnosis.
A total of 32.8 percent, or 40 people, had a shift from depression to bipolar disorder noted in their medical charts.
There were 10 years on average between depression diagnosis and bipolar diagnosis.
People with depression beginning at a younger age were more likely to shift from depression to bipolar disorder.
People who had a shift in diagnosis also had been in the hospital more, had been in treatment for a longer period of time and had sought treatment more often.
The authors concluded that some people with depression may be at risk for developing bipolar disorder. Factors, like hospitalizations and a longer time of treatment, may be help show who is at risk for a shift from depression to bipolar.
People with this type of medical history can be watched closely for a change in symptoms.
This study only looked at patient records. More research is needed in larger groups of people that are followed throughout their illness.
This study was published August 4 in the Journal of Affective Disorders. No conflicts of interest were provided.