Mayo Clinic researchers say people with bipolar disorder who also binge-eat experience a different disease progression than obese patients with bipolar disorder who do not binge-eat.

"Bipolar disorder, also known as manic-depressive illness, is a brain disorder that causes unusual shifts in mood, energy, activity levels and the ability to carry out day-to-day tasks," the National Institute of Mental Health says online. "Symptoms of bipolar disorder are severe. They are different from the normal ups and downs that everyone goes through from time to time. Bipolar disorder symptoms can result in damaged relationships, poor job or school performance and even suicide."

The NIH says that effective treatments are available, and that people can lead productive lives despite the illness.

According to Mayo, about 4 percent of Americans have some type of bipolar disorder. Among those, "just under 10 percent also have binge-eating disorder — a higher rate … than seen in the general population."

Patients with bipolar disorder who binge-eat also are more likely to deal with other mental-health issues such as suicidal thoughts, psychosis, anxiety disorders and substance abuse, the Journal of Affective Disordersstudy found.

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Conversely, those "with bipolar disorder who are obese but do not binge-eat are more likely to have serious physical problems such as arthritis, diabetes, high blood pressure and heart disease."

Researchers used the Mayo Clinic Bipolar Disorder Biobankto gain the new knowledge. They next hope to determine if there is a genetic link between binge-eating and bipolar disorder, while using the newly understood subgroup to help uncover the underlying cause of the disorder.

For individual patients, the discovery might not mean much on any given day. It can raise a question for patient and provider about mood.

"It really underscores the importance of trying to stabilize mood, because we know when people are symptomatic of their bipolar illness their binge frequency is likely to increase," Mayo's announcement quotes Dr. Mark Fryeas saying.

The goal, Frye said, is treatment that helps, but does not trigger, weight gain.

This a step forward for a subset of patients with bipolar disorder, but it also highlights the importance of people participating in research. You can do so if you have a chronic illness, and also if you are generally healthy.

Want to volunteer as a research participant? Mayo Clinic suggests these options:

• clinicaltrials.gov (studies nationally)

• clinicaltrials.mayo.edu (Mayo studies)

Pulse on Health is a weekly column by health reporter Jeff Hansel (285-7615). Follow him on Twitter @JeffHansel.