<P> For many, the symptoms of both depression and anxiety are not severe enough (i.e. are subsyndromal) to justify a primary diagnosis of either major depressive disorder (MDD) or an anxiety disorder . However, dysthymia is the most prevalent comorbid diagnosis of GAD clients . Patients can also be categorized as having mixed anxiety - depressive disorder, and they are at significantly increased risk of developing full - blown depression or anxiety . </P> <P> Various explanations for the high comorbidity between GAD and depressive disorders have been suggested, including genetic pleiotropy, meaning that GAD and nonbipolar depression might represent different phenotypic expressions of a common etiology . </P> <P> Those with GAD have a lifetime comorbidity prevalence of 30% to 35% with alcohol use disorder and 25% to 30% for another substance use disorder . People with both GAD and a substance use disorder also have a higher lifetime prevalence for other comorbidities . A study found that GAD was the primary disorder in slightly more than half of the 18 participants that were comorbid with alcohol use disorder . </P> <P> In addition to coexisting with depression, research shows that GAD often coexists with conditions associated with stress, such as irritable bowel syndrome . Patients with GAD can sometimes present with symptoms such as insomnia or headaches as well as pain, cardiac events and interpersonal problems . </P>

When are individuals typically diagnosed with anxiety disorder