eact and behave in ways that are culturally unacceptable and lead to distress and dysfunction in social and occupational situations. Ian J. Deary and his colleagues (1998, November) describe personality disorders as "long-standing, usually maladaptive, features of the person's behavior" (p. 647). The single most important feature is that the symptoms of personality disorders are always present. They do not go away in certain circumstances or over time.
Experts disagree about the number of people suffering from personality disorders, but some estimate that as many as 10 percent of the population is diagnosable (Hueston, 1996, January, p. 54); estimates range from 2 to 13 percent of the general population (Marlowe, 1997, July 19, p. 176). This includes individuals with mild symptoms, as well as those for whom these disorders completely dominate their lives. Clare Dyer (1999, July 24) notes, "Psychiatrists consider that most people with severe personality disorders are not treatable" (p. 210), while Steve Kisely (1999, May 22) argues that experts disagree on treatments but have not abandoned all hope for being able to help those with personality disorders deal more effectively with their world (p. 1410).
Psychologists disagree about the specific causes of personality disorders, though research suggests that borderline personality disorder, for instance, may be caused at least in part by sexual abuse and emotional or physical neglect (Childhood, 1997, November, p. 6). Experts have posited at least ten different theories about how personality disorders develop, ranging from the purely biological to some mixture of environmental vulnerability and childhood trauma. Some argue, for instance, that stress contributes to the development of personality disorders, while others contend that the presence of personality disorders makes the individual more vulnerable to stressful situations, aggravating the condition but not causing it in...