Abnormal Psychology

Personality Disorders 595

diagnosis of antisocial personality disorder is broader (i.e., less restrictive, because

there are fewer criteria) than the diagnosis of psychopathy. Moreover, the diagnosis

of antisocial personality disorder tends to focus more on behaviors—mostly crimi-

nal ones, such as stealing or breaking other laws—than on the personality traits that

may underlie the behaviors. In contrast, psychopathy emphasizes specifi c emotional

and interpersonal characteristics, such as a lack of empathy, an unmerited feeling

of high self-worth, and a refusal to accept responsibility for one’s actions—as well

as antisocial behaviors. Psychopathy is generally considered to be a more universal

concept than antisocial personality disorder; most cultures recognize a similar clus-

ter of psychopathic characteristics (Cooke, 1998; Gacono et al., 2001).

Research fi ndings refl ect the relative breadth of the criteria for antisocial person-

ality disorder compared to those for psychopathy: Although only a minority of pris-

oners (15% of male prisoners, 7.5% of female prisoners) meet the specifi c criteria for

psychopathy, a majority of prisoners (50–80%) meet the broad behavioral criteria

for antisocial personality disorder (Hare, 2003). And approximately 81% of people

diagnosed with psychopathy also meet criteria for antisocial personality disorder, but

only 38% of people diagnosed with antisocial personality disorder meet the criteria

for psychopathy (Hart & Hare, 1989; Hildebrand & de Ruiter, 2004; Stålenheim &

von Knorring, 1996; Sutker & Allain, 2001). In other words, although psychopathy

and antisocial personality disorder have elements in common, psychopathy is defi ned

more narrowly than antisocial personality disorder and with a different emphasis.

Understanding Antisocial Personality Disorder

The concept of psychopathy has been employed longer than the diagnosis of anti-

social personality disorder. Hence, more research has addressed psychopathy and

criminality than antisocial personality disorder—and the relative lack of research

on antisocial personality disorder makes it diffi cult to identify the factors that con-

tribute to the disorder (Ogloff, 2006). Moreover, most research that does examine

factors that contribute to antisocial personality disorder has studied participants

who are or have been in prisons or jails or who have comorbid substance abuse

problems, which makes it diffi cult to sort out the factors that contribute solely to

antisocial personality disorder. Therefore, the following sections examine neurolog-

ical, psychological, and social factors—and the feedback loops among them—that

contribute to antisocial personality disorder and/or psychopathy, keeping in mind

the limitations of existing research.

Neurological Factors in Antisocial Personality Disorder and Psychopathy

People with antisocial personality disorder or psychopathy (and the groups have

not been rigorously separated in most of this research) may have abnormal brain

structures as well as abnormal brain function (Pridmore, Chambers, & McArthur,

2005). There is also evidence that these people are genetically biased to develop cer-

tain temperaments, which may contribute to their disorder.

Brain Systems First, regarding brain structure, people with antisocial personality

disorder or psychopathy tend to have unusually small frontal lobes (Raine et al,

2000. and unusually small hippocampi (Laakso et al., 2001), but they have greater

than normal amounts of white matter (the fatty insulation on axons, see Chapter 2)

in the corpus callosum (the fi bers that form the primary connection between the

two cerebral hemispheres; Raine et al., 2003). The smaller frontal lobes might sug-

gest problems in inhibiting and planning behavior. It is tempting to suggest that the

smaller hippocampus refl ects the effects of stress (see the discussion of posttrau-

matic stress disorder in Chapter 7), but people with this personality disorder do not

generally perceive their situations as stressful, as other people would. Thus, it is not

clear how to interpret this brain abnormality.

Second, regarding brain function, the frontal and temporal lobes of these pa-

tients tend to show less activation than normal—especially when the patients par-

ticipate in tasks that involve classical conditioning (Schneider et al., 2000), tasks

that require inhibiting responses (Smith, 2000; Völlm et al., 2004), and tasks that

Although the concepts of psychopathy and anti-

social personality disorder overlap, they are not

the same. Most prisoners meet the criteria for

the diagnosis of antisocial personality disorder,

but only 15% at most meet the criteria for psycho-

pathy, which is defi ned more narrowly.

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Psychopathy

A set of emotional and interpersonal

characteristics marked by a lack of empathy,

an unmerited feeling of high self-worth,

and a refusal to accept responsibility for

one’s actions.