Date of Award

12-31-2017

Document Type

Open Access Thesis

Degree Name

Master of Arts (MA)

Department

Clinical Psychology

First Advisor

Paul G. Nestor

Second Advisor

Alice Carter

Third Advisor

Laurel Wainwright

Abstract

Neuropsychological impairment is a key characteristic of schizophrenia (SZ), but its cognitive profile and underlying information processing mechanisms are not yet well understood. We compare patterns of neuropsychological functioning in 85 persons with SZ and 76 healthy controls across measures of intelligence, memory, and executive function. We then test the hypothesis that neuropsychological impairment in SZ is related to dual deficits in two related but distinct information processes: processing speed and attentional control. All research participants completed Wechsler Adult Intelligence Scale-Third Edition (WAIS-III), Wechsler Memory Scale Third Edition (WMS-III), and Wisconsin Card Sorting Test (WCST), all of which provided measures of overall neuropsychological functioning. In addition, the neuropsychological battery included Trails B as a measure of attentional control and the WAIS-III Processing Speed Index (PSI). We hypothesized that a) patients with SZ will show a distinct pattern within and across measures of intelligence, memory, and executive functioning and b) attentional control and processing speed will each uniquely account for a significant portion of the variance in neuropsychological functioning across these measures. Our findings showed that WAIS-III Verbal Comprehension Index performance was primarily predicted by a slower Processing Speed Index (PSI), accounting for 12.25 % of the variance, and to a lesser extent by higher perseverative errors in the WCST(PE), accounting for 6.76% of the variance in the Verbal Comprehension Index. Perceptual Organization Performance was similarly primarily predicted by WAIS-III- PSI, which uniquely accounted for 30.25% of the variance and to a lesser extent by WCST PE, uniquely accounting for 15.21% of the variance. WMS-III Immediate General Memory Index was primarily predicted by the WAIS-III (PSI), accounting for 7.29 % unique of the variance, followed by WCST PE, accounting for 5.76 %. WMS-III Delayed General Memory performance was primarily predicted by WCST PE, uniquely accounting for 6.76% of the variance, yet PSI was not a significant predictor of the model in this domain. Overall, our study suggests that processing speed and secondarily attentional control mechanisms using the above proxy measures seem to account for unique portions of the variance in broad measures of overall intellectual functioning and declarative memory in SZ.

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