"Those in the top third of IL-6 at nine years had an increased risk of hypomanic symptoms aged 22 years, compared with those in the bottom third," the research paper says. What's more, that association apparently gets stronger when factors like sex, ethnicity and socio-economic status are taken into account. Asthma, eczema and C-reactive protein? None of those showed any relationship to hypomanic symptoms, while IL-6 and hypomania remained constant.

IL-6 itself is naturally produced by the body at times of aerobic exercise, fever, infection and other trauma. New Scientist writes that the chemical can alter how the brain works as well. Specifically, the subgenual cingulate area where anxiety, memory, mood, sleep and self-esteem are governed. Treating those affected areas could help allay the effects of bipolar disorder.