Atypical depression is a type of depressive illness that produces symptoms not usually found in people suffering from depression. Doctors can\u2019t directly diagnose these symptoms as a separate mental health condition; instead, they must include them as a secondary diagnosis when identifying other mental disorders. Apart from people affected by major depression, the people most likely to receive a secondary atypical depression diagnosis have either bipolar I disorder (the classic example of \u201cmanic depression\u201d) or a related condition called bipolar II disorder. Atypical Depression Basics Atypical depression was first described by doctors seeking to explain why some people with depression-related symptoms respond better to certain types of antidepressant medication, the authors of a 2006 study review in the journal Psychiatry report. The standard guidelines for identifying symptoms of the condition come from the American Psychiatric Association\u2019s Diagnostic and Statistical Manual of Mental Disorders. In order to qualify under these guidelines, an affected individual must have at least two of four potential symptoms for a minimum of two consecutive weeks. These symptoms include excessive sleepiness, heightened appetite levels, an unusual sense of heaviness in the extremities, and a persistent sensitivity to social rejection that appears even when the affected individual experiences an otherwise normal mood. A person with atypical depression must also experience an improvement in mood when positive events occur, and must lack symptoms of two mental states called catatonia and melancholia. People with atypical depression tend to share certain personality traits in common with people diagnosed with any one of three separate types of personality disorder, called avoidant personality disorder, borderline personality disorder and histrionic personality disorder. Examples of these shared traits include a tendency toward impulsive behavior, a relatively poor ability to think clearly, relatively easy provocation to anger, and a tendency toward anxiety, envy, and worry. Other personality characteristics frequently found in individuals affected by atypical depression include a tendency to give up on goals, a tendency to underachieve, and a tendency to fixate on past experiences of shame or embarrassment. Bipolar I Disorder and Bipolar II Disorder Bipolar I disorder is sometimes referred to as manic depression because people affected by the disorder typically experience prominent symptoms of an extremely agitated or energized state (known as mania), as well as prominent symptoms of depression that would otherwise qualify for an independent major depression diagnosis. While manic and depressed states usually appear separately, some people with the disorder experience mixed episodes of mania and depression. Bipolar II disorder also produces periods of depression serious enough to meet the definition for major depression. However, rather than experiencing episodes of outright manic behavior, people with this condition experience episodes of a less overt form of mania that mental health professionals call hypomania. Mixed periods of hypomania and depression do not occur in individuals diagnosed with bipolar II disorder. Points of Connection Atypical depression is strongly associated with the depressive stages of both bipolar I disorder and bipolar II disorder, and current evidence suggests that people affected by atypical depression have a genetic predisposition toward the development of bipolar illness. The link between atypical depression and the depressive stage of bipolar II disorder is particularly clear, the authors of the review in Psychiatry explain, and atypical symptoms may appear in more than half of the people affected by this illness. Generally speaking, people with bipolar I disorder or bipolar II disorder develop atypical depression symptoms at an earlier age than people with major depression or any other depression-related disorder. People affected by these bipolar conditions also commonly experience longer and more frequent periods of depression, and develop more pronounced symptoms of excessive sleepiness and arm and leg heaviness. Considerations Whether it appears in association with bipolar I disorder, bipolar II disorder or a depressive illness, atypical depression creates an increased risk for certain illness complications. The Mayo Clinic lists examples of these potential complications that include increased frequency of suicidal thinking, an increased tendency to make active suicide attempts, weight gain that\u2019s extreme enough to pose an independent health risk, increased risks for substance use, a greater likelihood of withdrawing from social contact, greater chances of developing anxiety disorders called social phobia and panic disorder, and an increased tendency to get involved in significant disputes with family members, intimate partners, school peers or teachers, and work peers or employers. Methods commonly or occasionally used to address the effects of atypical depression include psychotherapy, a range of antidepressant medications (such as SSRIs, atypical antidepressants, tricyclic antidepressants, or MAOIs), transcranial magnetic stimulation, and electroconvulsive therapy.