Eating disorders appear to occur more frequently in individuals with bipolar disorder.

According to a recent study, more than 14 percent of patients with bipolar disorder also suffer from an eating disorder, and these individuals are likely to have a more severe course of illness.

“Our findings are consistent with others suggesting that bipolar disorder may co-occur with eating disorders, and this relationship likely has clinical and theoretical significance,” according to Dr. Susan L. McElroy of the University of Cincinnati College of Medicine, who led the study with her colleagues.

Bipolar disorder, also known by its older name “manic depression,” is a mental disorder that is characterized by constantly changing moods. A person with bipolar disorder experiences alternating “highs” (what clinicians call “mania“) and “lows” (also known as depression). Bipolar disorder affects approximately 5.7 million American adults, and the median age of onset for bipolar disorders is 25 years. Eating disorders, which are more likely to affect women, affect slightly over four percent of the population, according to the National Institute of Mental Health.

To assess the frequency of eating disorders in this population, McElroy and her team enrolled 875 outpatients with bipolar I or II disorder in their study. Fifty-six percent of the patients were women, and the average age was 41.1 years. The participants completed questionnaires and were interviewed by clinicians to assess bipolar and eating disorder diagnoses. Eating disorder diagnoses included anorexia nervosa, bulimia nervosa, and binge eating disorder. Other information such as psychiatric history (including history of suicide attempts, rapid cycling, and age of onset of symptoms), family psychiatric history, other psychiatric diagnoses, and demographic information was also gathered.

The researchers found that 14.2 percent (125) of the study participants also had at least one eating disorder, with binge eating disorder (77) being the most common, followed by bulimia nervosa (42), and anorexia nervosa (27). The bipolar I and bipolar II patients had eating disorders at the same rate. The individuals who also had an eating disorder were more often women, and tended to have a more severe course of bipolar illness, with more mixed episodes, more prior episodes, more rapid cycling, and more suicide attempts. They also had on average a higher body mass index (BMI), more obesity or severe obesity. In addition, they were more likely to have a family history of substance abuse or mood disorders.

Among the patients with anorexia, anxiety disorders occurred more often. Bulimia disorder was associated with being overweight, and binge eating was more often associated with obesity or severe obesity.

“Substantial clinical and community data indicate that bipolar disorder co-occurs with substance use, anxiety, and impulse control disorders, and that these comorbidities are associated with negative effects on the course, outcome, and treatment response of bipolar disorder,” writes McElroy. “Another comorbidity which has received far less systematic attention but which may also be important is that between bipolar disorder and eating disorders.”

“Further research examining the overlap of these disorders would therefore appear to be just as important as further research into their differences.”

McElroy’s results were published online July 31 in the Journal of Affective Disorders.

Source: Journal of Affective Disorders