Abnormal Psychology

Dissociative and Somatoform Disorders 363

et al., 2005). As they note, dissociation can affect not only memory and the sense of

self, but can also disrupt the integration of sensory or motor functioning.

Other researchers argue that conversion disorder doesn’t really exist, but is a

type of factitious disorder: The patient is creating a socially sanctioned way to enact

a sick role, thereby manipulating others and avoiding responsibilities (Celani, 1976).

However, according to the DSM-IV-TR criteria, the symptoms would meet the crite-

ria for factitious disorder only if they are voluntarily—that is, consciously—created.

In many cases of conversion disorder, the symptoms do not appear to be consciously

created, and so factitious disorder would not be an appropriate diagnosis.

Understanding Conversion Disorder

Research on neurological factors in conversion disorders focuses on how brain

systems operate differently in people with the disorder. Psychological factors associ-

ated with the disorder include the role of self-hypnosis and dissociation. And a key

social factor is the role of intense stressors. Unfortunately, not enough is known to

understand how the various factors might infl uence each other.

Neurological Factors

By far, the bulk of neurologically oriented studies of conversion disorder have exam-

ined brain systems.

Brain Systems When contemplating the diagnosis of conversion disorder, clinicians

must rule out simple malingering or faking of symptoms. (Patients are sometimes

motivated to fake such illnesses in order to collect insurance, disability payments,

and so on.) Could all cases of conversion disorder just be faking? Neuroimaging

fi ndings suggest that muscle weakness arising from conversion disorder is not the

same as consciously simulated muscle weakness. For example, Stone and colleagues

(2007) scanned the brains of patients with conversion disorder and of healthy

controls while their ankles were fl exed. The patients with conversion disorder all

reported weakness in the manipulated ankle prior to the study; during the study,

participants in the control group were asked to pretend that their ankles were weak.

The results were clear: Some brain areas were more activated in the patients than

in the controls (such as the insula, which is involved in registering input from the

body) and some brain areas (including areas in the frontal lobes) were less acti-

vated in the patients than in the controls. These fi ndings are good evidence that the

patients were not simply faking their disorder.

In addition, some patients with chronic pain develop sensory defi cits, a kind

of “psychological” anesthesia. These patients often also have weakness (and

sometimes paralysis) of a limb, and they are typically classifi ed as having both

conversion disorder and a pain disorder. In one study aimed at discovering whether

such symptoms refl ect changes in how brain systems operate, researchers scanned

the brains of four such patients using fMRI, while sharp plastic fi bers were pressed

into the skin (Mailis-Gagnon et al., 2003). These patients had apparent sensory

defi cits in only one limb, and thus the researchers could directly compare stimula-

tion of the normal and affected limbs. When the researchers stimulated the nor-

mal limb, the sharp plastic fi bers activated a brain network that registers pain

(which includes the thalamus, the anterior cingulate cortex, the insula, and part of

the frontal lobe), as is normal. In contrast, this network was not activated when

the researchers stimulated the affected limb, as is shown in Figure 8.5. Moreover,

some brain areas—the somatosensory cortex (both the primary and secondary

areas) and parts of the parietal and frontal lobes—were activated less than nor-

mally when the researchers stimulated the affected limb. These fi ndings indicate

that the “psychological” anesthesia actually affected the brain and inhibited acti-

vation in the brain areas that register sensation and pain.

Another neuroimaging study examined patients with conversion disorder who

had a loss of sensation and motor control in one hand. These researchers used a

vibration device to stimulate both hands while recording blood fl ow in the brain.

They found decreased blood fl ow in the thalamus and the basal ganglia on the side