By Laura Cowen, medwireNews Reporter
Patients with bipolar disorder are more likely than healthy controls to have a history of weight cycling, which in turn is associated with an increased likelihood of manic and depressive episodes, researchers report.
The bipolar disorder patients included in the study by Harald Mangge (Medical University of Graz, Austria) et al also had significantly higher levels of the inflammatory cytokine interleukin (IL)-6 when they reported a history of weight cycling, compared with those who did not lose and gain weight repeatedly. This difference was apparent even after adjusting for body mass index (BMI), age and number of episodes.
The researchers explain that weight cycling is associated with cardiovascular morbidity and mortality, but its impact on patients with bipolar disorder, who are more likely than the general population to be overweight or obese due to factors such as medication use and a chaotic lifestyle, is unknown.
The team therefore investigated this phenomenon in 101 euthymic adults with bipolar disorder and 48 healthy controls.
The authors report in the Journal of Affective Disorders that weight cycling, defined as losing at least 4.5 kg at least three times in the previous 4 years, was significantly more common in the patients with bipolar disorder than in the healthy controls, at 30% versus 16%.
Among the patients with bipolar disorder, those who reported weight cycling had a significantly higher BMI (29.7 vs 27.4 kg/m2) and waist-to-height ratio (0.58 vs 0.55) compared with those who did not. They also had significantly more lifetime episodes of depression (19.7 vs 12.5) and mania (15.0 vs 8.0).
When Mangge et al looked at inflammatory markers, they found that weight cycling bipolar disorder patients had significantly higher levels of I-6 and high sensitivity C-reactive protein (hsCRP) than non-weight cycling bipolar disorder patients.
Furthermore, the number of depressive episodes correlated significantly with IL-6 and hsCRP levels, while the number of manic episodes correlated with hsCRP only. This finding was “expected” and “indicates an important role of chronic low grade inflammation in the pathophysiology of [bipolar disorder]”, say the researchers.
They also speculate that the link between weight cycling and pro-inflammatory cytokines could “identify a separate subpopulation with a greater susceptibility to cardiovascular disease.”
Mangge and co-authors conclude that “[p]sychiatrists should help to educate and motivate people with bipolar disorder to address their suboptimal lifestyle, including smoking, unhealthy diet and lack of exercise.”
They add: “In certain cases, a healthier lifestyle without weight loss might be the considered if weight loss is not going to be maintained.”
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