Abnormal Psychology

Clinical Diagnosis and Assessment 83

Similarly, consider Allie and Lupe, both

of whom are afraid of bugs and spiders. Lupe

mildly dislikes insects and avoids them whenever

possible, but she doesn’t freak out when she

sees a spider; Lupe’s fear of bugs doesn’t

reach the cutoff for a disorder (it doesn’t sig-

nifi cantly impair her functioning or cause her

excessive distress). Allie, in contrast, lives in

fear of spiders and refuses to open her win-

dows because she worries that spiders might

invade her apartment. As a result, the air is sti-

fl ing hot in her apartment during the summer.

Allie’s fear and avoidance of spiders are prob-

ably severe enough to be considered a disorder.

Heterogeneous Groups Have the Same

Disorder

For many DSM-IV-TR disorders, including

schizophrenia, a person needs to have only some of the symptoms in order to

be diagnosed with the disorder. For example, under Criterion A in Table 3.4, a

person needs to have only two out of the fi ve symptoms. This means that some

people with schizophrenia may have delusions and hallucinations, whereas oth-

ers may have disorganized speech and disorganized behavior, but no delusions

or hallucinations. Moreover, still other people classifi ed as having schizophrenia

may have negative symptoms and delusions, but not exhibit disorganized behav-

ior or experience hallucinations. Taken together, these three groups of people with

schizophrenia are heterogeneous—they are different from each other.

If the different combinations of symptoms do in fact refl ect a single underlying

disorder (in other words, if the category is valid), this is not a problem. But it is

possible—and many researchers believe it is likely (Messias & Kirkpatrick, 2001;

Tek et al., 2001)—that people who have different combinations of symptoms have

distinct types of schizophrenia, perhaps with different causes and prognoses. If so,

then it is an error to group them together. And this may be true for most disorders

in DSM-IV-TR. People with different combinations of symptoms may have devel-

oped the disorder in different ways, and different treatments might be effective.

Thus, the DSM-IV-TR diagnostic system may obscure important differences among

types of a given mental disorder (Malik & Beutler, 2002).

Symptoms Are Weighted Equally

In the DSM-IV-TR system, the diagnostic criteria for a given disorder, in essence,

produce a checklist; each criterion (and the symptoms refl ected in it, such as the

fi ve symptoms in Criterion A in Table 3.4) is generally weighted equally (Malik &

Beutler, 2002). But each symptom in the list of criteria for a given disorder may not

be equally important for diagnosis. For instance, patients with schizophrenia who

primarily have delusions or hallucinations are generally less impaired and have a

better prognosis than those who primarily have negative symptoms such as fl at af-

fect (diminished emotional expression) or diffi culty initiating goal-directed behavior

(McGlashan & Fenton, 1993).

Duration Criteria Are Arbitrary

Each set of criteria for a disorder specifi es a minimum amount of time that symp-

toms must be present for a patient to qualify for that diagnosis (see Criterion C in

Table 3.4). However, the specifi cation of a particular duration, such as that noted for

bulimia nervosa (which requires that the symptoms be present for at least 3 months),

is often arbitrary and not supported by research (Sullivan, Bulik, & Kendler, 1998).

The requirement for a specifi c duration also means that someone’s diagnostic

status can change literally overnight. For instance, for the diagnosis of social pho-

bia, symptoms of signifi cant fear in social situations must have persisted for at

Figure 3.1

3.1 • A Disorder as on a Continuum If a disorder such as schizophrenia is

best characterized along a continuum, then two people, Aaron and Max, diagnosed with

schizophrenia but with different severity or numbers of symptoms, would fall at different

points on the continuum. Aaron has fewer symptoms and is able to function better than

Max. According to DSM-IV-TR, they both have the same disorder. However, their illnesses

have different courses and prognoses and will likely require different types of treatment.

None of this information is captured by the categorical diagnostic system of DSM-IV-TR.

31 id C i

No Symptoms Cutoff for

diagnosis

Many, and

severe symptoms

Aaron Max