[Page 3271]Somatic symptom and related disorders are characterized by physical symptoms or concerns that may not be fully explained by an identified medical condition. However, they cause significant distress to individuals and can cause serious functional impairment. In fact, the essential common feature of these disorders is the significant distress and impairment associated with the somatic symptoms, rather than their “medically unexplained” nature. Despite the many common features among disorders on the same spectrum, current psychiatric nosology emphasizes discrete diagnostic entities as valid for somatic symptom and related disorders: (a) somatic symptoms (including a subtype with predominant pain), (b) functional neurological symptoms, (c) illness anxiety, (d) factitious disorders, and (e) psychological factors affecting other medical conditions—many of these also have a dimensional nature because illness ...