Cognitive, clinical, and functional characteristics of verbally superior schizophrenia patients.

Abstract

The existence of small numbers of schizophrenia patients with superior ability in specific cognitive domains is implied by meta-analytic evidence as well as by occasional empirical reports. The authors identified 25 patients with superior (i.e., > or =90th percentile) ability on the Vocabulary subtest of the Wechsler Adult Intelligence Scale 3rd edition (Wechsler, 1997). These cognitively advantaged patients were compared with 22 healthy participants performing at the superior level and with 126 schizophrenia patients and 50 healthy participants scoring below the superior range. Verbally superior schizophrenia patients and verbally superior healthy participants had similar cognitive profiles and life skills performance, but diverged markedly in terms of independent "real-world" functioning. Verbally superior patients significantly outperformed more typical patients in other aspects of cognitive performance, life skills, and support requirements. However, severity of positive and negative symptoms was equivalent in the patient groups. Detailed biobehavioral study of cognitively exceptional patients may offer new insights into mechanisms mediating psychotic disorders.

Development of brief versions of the Wechsler Intelligence Scale for schizophrenia: Considerations of the structure and predictability of intelligence

“…Likewise, Vocabulary requires executive skills, including efficient search and retrieval of target words, as well as a good knowledge of word meanings. In fact, patients with superior (4 90th percentile) performance on the Vocabulary subtest in the WAIS-3 exhibited a cognitive profile equivalent to that of healthy people showing superior verbal performance (Heinrichs et al, 2008).…”

Preserved, deteriorated, and premorbidly impaired patterns of intellectual ability in schizophrenia.

“…Hence, a substantial minority, 20-25%, must overlap with healthy people on many standard cognitive tasks. Indeed, a number of studies have corroborated the implications of meta-analytic findings and identified groups of patients with schizophrenia displaying statistically average levels of neuropsychological functioning (Ammari, Heinrichs, & Miles, 2010;Heinrichs et al, 2008;Kremen et al, 2000;Palmer, Dawes, & Heaton, 2009;Palmer et al, 1997;Rund et al, 2006;Weickert et al, 2000;Wexler et al, 2009). In a seminal study, using a combination of expert ratings and normative criteria, Palmer and colleagues (1997) identified 27.5% of their sample of schizophrenia patients as neuropsychologically normal on a variety of cognitive measures, including general intellectual ability or IQ.…”

“…The third tasks, although the common variance is seldom more than 15% (Ammari et al, 2010;Cobia et al, 2011;de Gracia Dominguez, Viechtbauer, Simons, van Os, & Krabbendam, 2009;Greenwood, Sigmundsson, Morris, & Wykes, 2000;Vaz & Heinrichs, 2006;Palmer et al, 1997), but others failed to find a relationship (Holthausen et al, 2002;Heinrichs et al, 2008;Palmer et al, 1997;Wexler et al, 2009). A similar discrepancy occurs with regards to disorganization symptoms in schizophrenia (Holthausen et al, 2002;Cobia et al, 2011).…”

“…Many studies of premorbid abilities in patients with normal cognitive performance did not find any evidence of a discrepancy between current and premorbid estimates of cognitive functioning based on reading tasks (McCabe et al, 2012;Heinrichs et al, 2008;Weikert et al, 2000).…”

“…Furthermore, there are reports of even higher-functioning patient subgroups. Recent studies show that a much smaller, but potentially important, subgroup of patients demonstrates verbal ability at or above the 90 th percentile, based on Vocabulary scores from the Wechsler Adult Intelligence Scale (Heinrichs et al, 2008), an indicator of general intellectual ability. Others have also identified patients who have IQs above the average range (Kremen, Seidman, Faraone, & Tsuang, 2001;McCabe, Maloney, Stain, Loughland, & Carr, 2012;Weikert et al, 2000;Wilk et al, 2005).…”