Ans. A. 2 weeksMajor depression is defined as depressed mood on a daily basis for a minimum duration of 2 weeks. An episode may be characterized by sadness, indifference, apathy, or irritability and is usually associated with: changes in sleep patterns, appetite, and weight; motor agitation or retardation; fatigue; impaired concentration and decision-making; feelings of shame or guilt; and thoughts of death or dying. Patients with depression have a profound loss of pleasure in all enjoyable activities, exhibit early morning awakening, feel that the dysphoric mood state is qualitatively different from sadness, and of- ten notice a diurnal variation in mood (worse in morning hours).Some chronic disorders of uncertain etiology, such as chronic fatigue syndrome and fibromyalgia, are strongly associated with depression and anxiety; patients may benefit from antidepressant treatment, usually at lower than normal dosing.