Abnormal Psychology

Cognitive Disorders 687

that cognitive functioning improves as the symptoms resolve or the pain recedes.

In other cases, though, the person may never return to his or her prior level of

functioning.

In still other cases, an older adult may appear to have impaired cognitive func-

tioning but actually has undiagnosed or uncorrected sensory problems, such as hear-

ing loss or vision problems. If someone chronically mishears what is said, he or she

will seem “not with it” or “senile” when, in fact, the problem is simply that the indi-

vidual thinks the topic of conversation is something other than what it actually is.

Stroke

Astroke (so named because it was originally assumed to be a “stroke of God”) is

the interruption of normal blood fl ow to or within the brain (often because of an

obstruction—such as a blood clot—in a blood vessel). The result is that part of the

brain fails to receive oxygen and nutrients, and the neurons in that area die. The

cognitive, emotional, and behavioral consequences of a stroke depend crucially on

which specifi c group of neurons is affected; depending on their location, different

defi cits are produced. In the following sections, we briefl y consider some of the

more common defi cits.

Aphasia

Aphasia is a problem in using language. (The wordaphasia literally means “an ab-

sence of speech.”) Traditionally, there are two main types of aphasia, each named

after a neurologist who fi rst characterized it in detail. Broca’s aphasia is charac-

terized by problems producing speech and often occurs after damage to part of

the left frontal lobe. Patients with Broca’s aphasia speak haltingly, and their speech

can be very telegraphic—consisting of only the main words. In addition, they typi-

cally don’t use grammar correctly; for example, these patients often omit words

such as and, or, and of. In contrast, Wernicke’s aphasia is characterized by prob-

lems with both comprehension of language and production of meaningful utter-

ances. This disorder often occurs after damage to part of the rear portions of the

left temporal lobe. Although these patients may appear to speak fl uently, they of-

ten order words incorrectly and sometimes make up nonsense words. For instance,

when asked to describe his occupation prior to suffering a stroke, one patient with

Wernicke’s aphasia said, “Never, now mista oyge I wanna tell you this happened

when happened when he rent” (Kertesz, 1981, p. 73, as cited in Carlson, 1994,

p. 517). Clinicians sometimes have diffi culty distinguishing between schizophrenia

and Wernicke’s aphasia. However, people with schizophrenia (except perhaps when

extremely psychotic) can understand speech and name objects better than can pa-

tients with Wernicke’s aphasia (Mendez & Cummings, 2004).

Agnosia

Patients who have agnosia have diffi culty understanding what they perceive, al-

though neither their sensory abilities nor their knowledge about objects is impaired.

Many forms of agnosia can arise, but two are most common. Apperceptive agnosia

occurs when a person cannot organize visual input into objects and their spatial

relations. As a consequence, a person with apperceptive agnosia cannot determine

whether two shapes are the same or different and thus cannot copy a drawing. (This

disorder may arise following carbon monoxide poisoning, which produces diffuse

damage in the occipital lobe.) This disorder can lead to disorientation, which must

be distinguished from disorientation that occurs with dementia (to be discussed

shortly).

The other common form of agnosia, associative agnosia, occurs when a person

can visually organize shapes appropriately, and hence can see objects, but cannot

associate the shape with its meaning—and hence cannot understand what he or she

is seeing. Thus, someone with associative agnosia is able to tell whether two objects

are the same or different, and can copy a drawing of a stick fi gure, but doesn’t

understand that the lines and circle of the stick fi gure represent a human. Here’s

another example of the type of problems that arise with associative agnosia: One of

A stroke is an interruption of normal blood fl ow to

the brain that causes neurons in that part of the

brain to die. The effect of a stroke depends on its

location in the brain and the size of the brain area

that it affects. This image shows a colored MRI

scan of the brain of a woman who had a stroke,

with red indicating dead brain tissue and green

indicating healthy tissue.

Simon Fraser / Royal Victoria Infi rmary, Newcastle upon Tyne / Photo Researchers

Stroke

The interruption of normal blood fl ow to or

within the brain, which results in neuronal

death.

Aphasia

A neurological condition characterized by

problems in producing or comprehending

language.

Broca’s aphasia

A neurological condition characterized by

problems producing speech.

Wernicke’s aphasia

A neurological condition characterized by

problems comprehending language and

producing meaningful utterances.