Schizophrenia and Other Psychotic Disorders 525
2004). Executive functions are required to organize, interpret, and transform
informationin working memory—and hence a problem with such functioning will
disrupt working memory. But more than this, the problems with executive functioning
have far-reaching consequences for cognition in general. For instance, Hester had the
most severe symptoms of the Genain quads, and her defi cits in executive functioning
were prominent much of the time. She had diffi culty performing household chores
that required multiple steps—such as making mashed potatoes by herself, which
required peeling the potatoes, then boiling them, knowing when to take them out
of the water, and mashing them with other (measured) ingredients. When Hester
was not actively psychotic, she would be able to perform the fi rst step of a multistep
task, but only after she had fi nished that step could she begin to plan and implement
a second step. After she completed each step, she needed to receive instructions
for the next one. Obviously, defi cits in executive functioning can impair a person’s
overall ability to function.
Cognitive Defi cits Endure Over Time
Neurocognitive defi cits do not necessarily make their fi rst appearance at the same
time that the DSM-IV-TR symptoms of schizophrenia fi rst emerge. For many people
who develop schizophrenia, cognitive defi cits exist in childhood, well before a fi rst
episode of schizophrenia (Cannon et al., 1999; Erlenmeyer-Kimling et al., 2000;
Fish et al., 1992; Fuller et al., 2002; Ott et al., 2002; Torrey, 2002). In addition to
predating symptoms of schizophrenia, cognitive defi cits often persist after the DSM-
IV-TR symptoms improve (Hoff & Kremen, 2003; Hughes et al., 2003; Rund et al.,
2004; Tsuang, Stone, & Faraone, 2000).
The lives of Genain sisters illustrate both the importance of cognitive defi citsand their variety. Hester had the most diffi culty academically and was held back
in 5th grade because of her inadequate school performance. Moreover, she had
diffi culty carrying out simple household tasks and seemed to suffer from defi cits
in attention, memory, and executive functioning. The cognitive functioning of
the other quads did not appear to be as impaired. In fact, Myra did not exhibit
any signifi cant cognitive defi cits, and she graduated from high school, held a job,
married, and had two children. Nora and Iris had moderate levels of cognitive
defi cits; they could perform full-time work for periods of time but could not
function independently for long stretches (Mirsky & Quinn, 1988; Mirsky et al.,
1987, 2000).
Limitations of DSM-IV-TR Criteria
Although the DSM-IV-TR criteria provide a relatively reliable way to diagnose
schizophrenia, a number of researchers point to drawbacks of those criteria—both
of the specifi c criteria and of the grouping of positive and negative symptoms (Fauman,
2006; Green, 2001). A more diagnostically and prognostically relevant set of symptoms,
these researchers suggest, would focus on the extent of cognitive defi cits and the
breadth and severity of the DSM-IV-TR symptoms.
Absence of Focus on Cognitive and Social Functioning
Cognitive defi cits are not specifi cally addressed by the DSM-IV-TR criteria, despite
their importance. Specifi cally, although the DSM-IV-TR set of positive symptoms
includes disorganized speech and disorganized behavior (see Table 12.1), research
suggests that these two symptoms together form an important cluster, independent
of hallucinations and delusions. Moreover, these symptoms arise from underlying
cognitive defi cits that contribute to disorganized thinking. For instance, cognitive
defi cits can cause thoughts to skip from one topic to another, topics that are related
to each other only tangentially if at all (this problem is referred to as a loosening
of associations). Thus, disorganized speech arises from disorganized thinking, but
such thinking is not part of the DSM-IV-TR criteria. Similarly, disorganized behav-
ior, such as laughing at a funeral or putting on four pairs of underwear, can arise
because the individual’s cognitive defi cits prevent him or her from organizing social
experiences into categories covered by general rules of behavior or conventions.