What Causes Bipolar Disorder? Scientists Think They’ve Found 7 Potential Sources Of The Illness

Mental health issues are complex, and severe illnesses like bipolar disorder have long been been critically misunderstood. Though bipolar disorder was identified in writings as early as the first century, and has been included in the DSM since 1980, there is still a lot of information that's missing about the disorder. Not only is bipolar disorder underdiagnosed and even misdiagnosed, but what causes bipolar disorder is a often contentious topic among mental health professionals. But research into the potential causes is beginning to shed new light on the subject. Scientists at the University of Michigan think they’ve found seven different causes of the illness after a 12-year-long study.

The research was conducted by a team at The Heinz C. Prechter Bipolar Research Fund, a program that supports University of Michigan’s Depression Center. For over a decade, the scientists studied 1,100 people — 730 people diagnosed with bipolar disorder, and 277 who weren’t — before coming to the conclusion that the mental health disorder has not one, but seven potential risk factors. Their findings were published in the International Journal of Epidemiology on Dec. 2.

"There are many routes to this disease, and many routes through it," said Melvin McInnis, M.D., the main author of the paper and University of Michigan Professor of Bipolar Disorder, Depression, and Psychiatry, in a press release. "We have found that there are many biological mechanisms which drive the disease, and many interactive external influences on it. All of these elements combine to affect the disease as patients experience it."

Dr. McInnis and his colleagues analyzed copious amounts of data on genetics, lifestyle habits, such as diet and sleep patterns, emotions, life experiences, medical history, and other thought and behavior patterns. They identified "seven Phenotypic classes," or simply put, seven potential causes of bipolar disorder. The classes are:

  • "Disease," meaning genetic risk factors or predisposition could make you more vulnerable to developing bipolar disorder;
  • "Neurocognitive," which examines thought and emotion patterns;
  • "Temperament Personality," which looks at personality traits, behaviors, and activity;
  • "Motivated Behaviors," including activities such as substance use and substance use disorder;
  • "Life Story," examining experiences and possible traumas;
  • "Sleep and Circadian," meaning the influence of sleep on the disorder;
  • "Outcomes and Course," which measure the change or improvement of bipolar symptoms with time, and medical treatment.

In addition to the seven possible causes that the University of Michigan team noted, they reported several key factors and trends in people with bipolar disorder. People with bipolar disorder, they found, were more likely to have co-occurring eating disorders, anxiety disorders, and substance use issues, as well as metabolic syndrome. Additionally, bipolar patients were three and a half times more likely to experience chronic migraines. Many study participants with bipolar disorder experienced some sort of childhood trauma, more so than the the participants not diagnosed with the mental illness. Additionally, women who participated in the study experienced an influx of severity in bipolar symptoms if they had poor sleep. However, sleeping habits did not seem to affect men diagnosed with bipolar disorder.

The researchers also found that two genes seem to make you more susceptible to developing bipolar disorder, but also acknowledged that there were many different genetic variations that have been linked to the disorder. Interestingly, they also saw that cognitive abilities — such as memory and fine motor skills — were poorer in study participants who had bipolar disorder. The authors noted that the classes "include standard measures doctors already use to diagnose" bipolar disorder.

The National Alliance on Mental Illness defines bipolar disorder as a “a mental illness that causes dramatic shifts in a person’s mood, energy and ability to think clearly.” The disorder is characterized by varying periods of high moods (aka, mania) and low moods (depression). Additionally, there are several types of bipolar disorder: most commonly, Bipolar Type 1 is diagnosed when the patient experiences increased mania, while Bipolar Type 2 patients experience more intense depressive episodes as well as hypomania, or a mild form of mania. Both are serious, and pose an increased risk of suicide. According to international figures released in 2011, around 2.4 percent of the people around the globe have been diagnosed with bipolar disorder in their lifetime. The National Institute of Mental Health (NIMH) also reports that 2.6 percent of American adults, or nearly 6 million people, are diagnosed with the mental health issue. Moreover, 82.9 percent of these cases are classified as “severe” by the NIMH.

Treating bipolar disorder is can be difficult; the International Bipolar Foundation recommends a combination of treatments including medication, psychotherapy, additional peer support, education, and management of lifestyle risk factors. However, the University of Michigan research could provide more insight on how to effectively treat the mental illness. "We hope this new framework will provide a new approach to understand this disorder, and other complex diseases, by developing models that can guide a management strategy for clinicians and patients, and give researchers consistent variables to measure and assess,” Dr. McInnis explained.

Though more research needs to be done to confirm the findings of this study, it provides some new insight into the potential causes bipolar disorder. The study also indicates a needed change in how professionals must think about chronic health issues — mental and physical illnesses — and how they need to treat chronically ill patients with compassionate and individualized care. "Bipolar disorder has a lot to teach humankind about other illnesses, because it covers the breadths of human mood, emotion and behavior like no other condition,” said Dr. McInnis. “What we can learn in bipolar about all these factors will be directly applicable to monitoring other disorders, and personalizing the approach to managing them."

Like many chronic illnesses, understand and treating bipolar disorder will take ample research, and much trial and error. But, improving the lives of people who live with bipolar disorder begins with acknowledging how complex it truly is, and that there is no one-size-fits-all treatment program.