Abnormal Psychology

Clinical Diagnosis and Assessment 93

In addition to using MRS, researchers measure the levels of chemical by-

products of neurotransmitters in blood, urine, or cerebrospinal fl uid (the fl uid that

surrounds the brain and spinal cord) in order to get a sense of the role of neurotrans-

mitters in psychological disorders. For example, Geracioti and colleagues (2006)

studied the cerebrospinal fl uid of patients who had major depression or posttrau-

matic stress disorder (PTSD) and found in both groups higher than normal levels of

a by-product of substance P (a neurotransmitter substance known to be involved

in registering pain). The researchers also found that more of this by-product was

present when the patients with PTSD viewed aversive videos (which triggered their

symptoms) than when they viewed neutral videos. Such studies can not only provide

information about neurological and other biological differences that characterize

people who have different disorders, but also help reveal why specifi c stimuli can

exacerbate the symptoms of a disorder.

Furthermore, PET techniques that use ligands, radioactive molecules that

mimic neurotransmitters, can reveal where receptors for given neurotransmitters

are located in the brain. As noted in Chapter 2, some aspects of mental illness may

be related to dysfunctional receptor systems. For example, Tauscher and colleagues

(2001) injected a ligand that mimics serotonin into the blood of healthy volunteers

and observed how much of that ligand bound to one type of serotonin receptor.

They also found that people who had higher levels of anxiety showed less binding

of this ligand.

Researchers and clinicians also want to assess the levels of specifi c hormones

to determine whether they may contribute to mental illness. For instance, symp-

toms of depression are sometimes caused by low levels of the hormone thyroxin,

which is measured by a blood test (Pfennig et al., 2004). Depressed individuals who

have low levels of thyroxin might be prescribed thyroid supplements as part of their

treatment (Altshuler et al., 2001).

Neuropsychological Assessment

An assessment of neurological factors may include neuropsychological testing,

which uses behavioral responses to test items in order to draw inferences about

brain functioning. Assessing neuropsychological functioning allows clinicians and

researchers to distinguish the effects of brain damage from the effects of psycho-

logical problems (for example, disrupted speech can be caused by either of these).

Neuropsychological assessment is also used to determine whether brain damage

is contributing to psychological problems (for example, frontal lobe damage can

disrupt the ability to inhibit aggressive behavior). Unlike functional neuroimag-

ing, which identifi es brain areas activated during a given task (relative to another

task), neuropsychological testing gives a broad picture of the brain’s functioning.

A neuropsychological assessment determines the sorts of basic functions that the

brain can do effectively, can do with effort, or cannot perform. Moreover, the re-

sults can suggest that specific parts of the brain may be damaged.

Although much less precise, such testing is signifi cantly less expensive

and easier to administer than neuroimaging, and it can be given in

any quiet room.

Neuropsychological tests range from those that assess complex

abilities (such as judgment or planning) to those that assess a rela-

tively specifi c ability, such as the ability to recognize faces (measured

by the Facial Recognition Test; Benton et al., 1983). For example, in

one version of the Facial Recognition Test, a patient is shown a photo

of a “target” face, then a set of six photos of faces from which the

patient must pick out the target. In another version of the Facial Rec-

ognition Test, the six photos differ in lighting or orientation, and the

patient must pick out the three that show the target face. Other neu-

ropsychological tests, such as the Bender Visual-Motor Gestalt Test-II

(2nd edition) (Bender, 1963; Brannigan & Decker, 2003), assess more

Neuropsychological testing

The employment of assessment techniques

that use behavioral responses to test items

in order to draw inferences about brain

functioning.

The Rey Osterrieth Test requires the test-taker

to copy a complex fi gure, and then draw it from

memory; the test assesses visual perception,

organizational ability, and memory.

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