Scientists Conclude After 12-year Study That Bipolar Disorder Has Seven Causes

research team
Credit to user Army Medicine. Used with permission under a Creative Commons license.

After more than a decade of observing 1,100 study participants, University of Michigan researchers have classified bipolar disorder’s causes into seven different phenotypes, or observable characteristics.


In a new paper in the International Journal of Epidemiology, the U-M team reports the results of thousands of data points of the study participants, including genetics, emotions, life experiences, medical histories, motivations, diets, temperaments, sleep patterns and thought patterns. More than 700 research volunteers suffer from bipolar disorder, and 277 do not.

The research team is part of U-M’s Heinz C. Prechter Bipolar Research Program, funded by many donors and named after a successful Detroit car baron who battled bipolar disorder.

In addition to the standard measures doctors use to diagnose bipolar disorder, the seven “phenoclasses” include:

  • changes in thinking, reasoning, and the processing of emotions;
  • personality and temperament;
  • “motivated behaviors” — related to substance use or abuse;
  • family and intimate relationships;
  • sleep patterns; and
  • how patients respond to treatment.

Other key findings include:

  • Migraine headaches occure three and a half times more frequently in people with bipolar disorder. Eating disorders and anxiety disorders are also more common, as well as alcohol abuse.
  • People with bipolar disorder tend to have a history of childhood trauma.
  • People suffering from bipolar disorder eat more saturated fats, and levels of certain fat molecules in the blood of patients are associated with higher levels of symptoms.
  • There is less diversity of gut bacteria in people taking antipsychotic medications. Lower levels of a key bacteria type in the gut were also found.
  • Poor sleep affects depression in female participants. Other gender differences were found.
  • Neurotic people with bipolar disorder were more likely to have severe illness. Especially men.
  • People with bipolar disorder have poorer memories, executive functioning, and motor skills.
  • Speech patterns can predict mood states. 


    The research team hopes that their study will enable a multi-pronged approach to diagnosis and treatment of patients with bipolar disorder.

    Materials provided by Michigan Medicine – University of Michigan.