688 CHAPTER 15
us (SMK) once saw a patient who could not name a comb when shown it but could
say what color it was and could reach for it and hold it properly. Moreover, as soon
as the patient felt the comb with his fi ngers, he could name it easily. The problem
was not that he had forgotten the name or that he was unable to retrieve or say the
name—rather, it was an inability to make the connection between (that is, to as-
sociate) the visual form and the appropriate information stored in memory (Farah,
2004; Kosslyn & Koenig, 1995). Clinicians must distinguish between this kind of
problem with object recognition and the sort of disorientation that may accompany
severe psychosis, as sometimes occurs with schizophrenia.Apraxia
Another medical condition that can affect cognitive functioning is apraxia (Kosslyn &
Koenig, 1995), which involves problems in organizing and carrying out voluntary
movements even though the muscles themselves are not impaired. The problem is
in the brain, not in the muscles. Apraxia can take a variety of forms; some patients
have trouble with individual components of a series of movements (such as pinch-
ing thumb and forefi nger to pick up a coin), whereas others have trouble sequencing
movements (such as the movements necessary to light a candle, that is, taking out
a match, striking it, and holding the fl ame to the wick). Clinicians must distinguish
between such problems with voluntary movements and the avolition (diffi culty
initiating or following through with activities) that may accompany schizophrenia
(noted in Chapter 12).Head Injury
Cognitive disorders can arise from head injuries—which may result from a car ac-
cident, from a fall, or in a variety of other ways. The specifi c cognitive defi cits that
develop depend on the exact nature of the head injury. The same kinds of defi cits
that follow a stroke can also occur after a head injury.Substance-Induced Changes in Cognition
We saw in Chapter 9 that some people take substances (including prescribed medi-
cations) to alter their level of awareness or their emotional or cognitive state. But
medications or exposure to toxic substances can produce unintended changes in
attention, memory, judgment, or other cognitive functions, particularly when a high
dose is taken. In fact, older people are more sensitive to the effects of medications,
and so a dose appropriate for a younger adult is more likely to have negative effects
or side effects in an older adult (Mort & Aparasu, 2002). Even anesthesia for sur-
gery can subsequently affect cognitive functioning (Thompson, 2003).
To determine whether psychological or medical disorders are causing an indi-
vidual’s decline in cognitive functioning, the clinician may take a number of steps
(Harvey, 2005a; Rabin et al., 2006). Specifi cally, he or she may- interview and observe the patient;
- speak with the patient’s family or friends or someone else who knows the patient
and his or her history; - obtain a medical examination by an internist or neurologist;
- ask for laboratory testing to be performed, such as blood tests or neuroimaging
tests; - review the patient’s recent and current medications;
- assess the patient’s ability to function in daily life; and
- obtain neuropsychological testing to determine the specifi c cognitive abilities that
are impaired.
All of these steps were taken when Mrs. B. was being diagnosed in order to
determine the nature of her problems—her memory diffi culties and her disruptive
behaviors that made it diffi cult for her to live in supervised residential settings.Apraxia
A neurological condition characterized by
problems in organizing and carrying out
voluntary movements even though the
muscles themselves are not impaired.
Delirium
A cognitive disorder characterized by a
disturbance in consciousness and changes
in cognitive functioning, particularly in
attention.