Neurocognitive trait markers in schizophrenia

Wendell Alan Rohrer, Purdue University

Abstract

The present study identified hypothetical schizotypal subjects from a nonclinical setting and compared their performance on a battery of neuropsychological assessment devices to that of two control groups. The purpose of the current investigation was to determine whether relatively poor performance on various neuropsychological measures might be characteristic of the schizotypals and might, therefore, represent a trait marker of schizophrenia. The MMPI 2-7-8 code type was used in identifying the hypothetically schizotypal subjects (n = 15). Subjects producing inflation-free (n = 15) and 4-9 (n = 15) MMPI code types served as normal and "psychiatric" control groups. Subjects were administered the Wechsler Memory Scale - Revised Logical Memory I, Verbal Paired Associates I, and Visual Reproduction I subtests in addition to the Tactual Performance Test (TPT), Speech-Sounds Perception Test, and the Trailmaking Test. These neuropsychological tests were chosen to be included in the current study because previous research had suggested that they might identify trait deficits associated with schizophrenia spectrum disorders. However, the results of the present investigation did not support this contention. The hypothetical schizotypals did not differ statistically from the control groups in their performance on these measures. Additionally, the majority of subjects in all groups did not evidence impaired performance on any of the neuropsychological measures. Several subjects in all three groups evidenced "impaired" performance on one measure, the TPT-Location subtest, suggesting that the norms on this test need to be adjusted. The results of the current study also suggest that future research needs to match index and control groups with regard to gender and handedness whenever possible. Left-handedness was more common among 2-7-8 subjects than among controls in the present investigation, even though a comparison of all 2-7-8 subjects to all controls identified over a six year screening period did not find an increased incidence of left-handedness among the hypothetical schizotypals. Results are discussed in terms of validity of the 2-7-8 index as a measure of schizotypy, the sensitivity of the neuropsychological measures, and the implications of using high functioning, college student subjects to evaluate neuropsychological differences.

Degree

Ph.D.

Advisors

Merritt, Purdue University.

Subject Area

Psychotherapy|Psychological tests

COinS