May 26, 2010 (New Orleans) -- People with bipolar disorder are two to four times as likely as people without the disorder to suffer from various skin conditions, including psoriasis and eczema, researchers report.
They're also 2.6 times more likely to have hypothyroidism, 2.3 times more likely to have hay fever, 90% more likely to suffer from migraine headaches, 60% more likely to have viral hepatitis, 60% more likely to be obese, 40% more likely to have asthma, and 40% more likely to have epilepsy than other people, says Jared A. Fisher, MPH, of the Walter Reed Army Institute of Research in Silver Spring, Md.
Others may share a common causal factor with bipolar disorder, he says. For example, some research shows that bipolar disorder, increased body weight, and hypertension are all related to elevated norepinephrine levels.
"But with others, we just have no idea as to why [rates are higher in people with bipolar disorder].
"We're just trying to find the most common disorders in people with bipolar disease and set the stage for future research," Fisher says.
The findings were presented at the American Psychiatric Association meeting.
Previous research has shown that 40% to 56% of people with bipolar disorder have been diagnosed with one or more other medical conditions, Fisher says.
For the current study, the researchers used data from the 1979-2006 National Hospital Discharge Survey (NHDS) to compare rates of various diseases in 27,054 people with bipolar disorder and 2,325,247 people without the disorder.
The researchers say that one strength of the study is that it used a large, nationally representative database.
A weakness is that it relied solely on hospital discharge data, so a person who goes in and out of the hospital could be counted more than once.
Philip Muskin, MD, professor of clinical psychiatry at Columbia University in New York City, says that one reason people with bipolar disorder may be more likely to develop certain disorders is that "they don't always get good medical care because many don't like to go see doctors. A lot of times, when I say to patients, 'Let’s talk to your internist,' they reply that they don't have one. I consider it my job to help them find an internist."