http://archpsyc.jamanetwork.com/ en-us Wed, 12 Jun 2013 00:00:00 GMT Wed, 12 Jun 2013 16:45:11 GMT Silverchair editor@archpsyc.jamanetwork.com webmaster@archpsyc.jamanetwork.com http://archpsyc.jamanetwork.com/article.aspx?articleID=1696348 Wed, 12 Jun 2013 00:00:00 GMT Benros ME, Waltoft BL, Nordentoft M, et al. <span class="paragraphSection"><div class="boxTitle">Importance</div>Mood disorders frequently co-occur with medical diseases that involve inflammatory pathophysiologic mechanisms. Immune responses can affect the brain and might increase the risk of mood disorders, but longitudinal studies of comorbidity are lacking.<div class="boxTitle">Objective</div>To estimate the effect of autoimmune diseases and infections on the risk of developing mood disorders.<div class="boxTitle">Design</div>Nationwide, population-based, prospective cohort study with 78 million person-years of follow-up. Data were analyzed with survival analysis techniques and adjusted for calendar year, age, and sex.<div class="boxTitle">Setting</div>Individual data drawn from Danish longitudinal registers.<div class="boxTitle">Participants</div>A total of 3.56 million people born between 1945 and 1996 were followed up from January 1, 1977, through December 31, 2010, with 91 637 people having hospital contacts for mood disorders.<div class="boxTitle">Main Outcomes and Measures</div>The risk of a first lifetime diagnosis of mood disorder assigned by a psychiatrist in a hospital, outpatient clinic, or emergency department setting. Incidence rate ratios (IRRs) and accompanying 95% CIs are used as measures of relative risk.<div class="boxTitle">Results</div>A prior hospital contact because of autoimmune disease increased the risk of a subsequent mood disorder diagnosis by 45% (IRR, 1.45; 95% CI, 1.39-1.52). Any history of hospitalization for infection increased the risk of later mood disorders by 62% (IRR, 1.62; 95% CI, 1.60-1.64). The 2 risk factors interacted in synergy and increased the risk of subsequent mood disorders even further (IRR, 2.35; 95% CI, 2.25-2.46). The number of infections and autoimmune diseases increased the risk of mood disorders in a dose-response relationship. Approximately one-third (32%) of the participants diagnosed as having a mood disorder had a previous hospital contact because of an infection, whereas 5% had a previous hospital contact because of an autoimmune disease.<div class="boxTitle">Conclusions and Relevance</div>Autoimmune diseases and infections are risk factors for subsequent mood disorder diagnosis. These associations seem compatible with an immunologic hypothesis for the development of mood disorders in subgroups of patients.</span> 1 9 10.1001/jamapsychiatry.2013.1111 http://archpsyc.jamanetwork.com/article.aspx?articleID=1696348