Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-11-25T21:08:59.415Z Has data issue: false hasContentIssue false

Estimation of Premorbid Intelligence in Schizophrenia

Published online by Cambridge University Press:  02 January 2018

J. R. Crawford*
Affiliation:
Department of Psychology, University of Aberdeen, Aberdeen AB9 2UB
J. A. O. Besson
Affiliation:
Department of Mental Health, Medical School, University of Aberdeen
M. Bremner
Affiliation:
Department of Mental Health, Medical School, University of Aberdeen
K. P. Ebmeier
Affiliation:
Department of Mental Health, Medical School, University of Aberdeen
R. H. B. Cochrane
Affiliation:
Department of Mental Health, Medical School, University of Aberdeen
K. Kirkwood
Affiliation:
Department of Mental Health, Medical School, University of Aberdeen
*
Correspondence

Abstract

To determine whether the National Adult Reading Test (NART) would provide a valid estimate of premorbid intelligence in schizophrenia, two schizophrenic samples were recruited, one consisting of 35 patients resident in long-stay wards, the other of 29 patients normally resident in the community. Schizophrenic patients were individually matched for age, sex, and education with a healthy, normal subject. Both schizophrenic samples scored significantly lower on the Wechsler Adult Intelligence Scale (WAIS) than their respective control groups. NART-estimated IQ did not differ significantly between the community-resident schizophrenics and their controls, suggesting that the NART provides a valid means of estimating premorbid intelligence in such a population. NART-estimated IQ was significantly lower in the long-stay sample than in their controls. Although low NART scores in this latter sample could be a valid reflection of low premorbid IQ, the alternative explanation that NART performance was impaired by onset of the disease cannot be ruled out.

Type
Papers
Copyright
Copyright © 1992 The Royal College of Psychiatrists 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Acker, C., Jacobson, R. R. & Lishman, W. A. (1987) Memory and ventricular size in alcoholics. Psychological Medicine, 17, 343348.CrossRefGoogle ScholarPubMed
Albee, G., Lane, E., Corcoran, C., et al (1963) Childhood and intercurrent intellectual performance of adult schizophrenics. Journal of Consulting Psychology, 27, 364366.CrossRefGoogle ScholarPubMed
American Psychiatric Association (1980) Diagnostic and Statistical Manual of Mental Disorders (3rd edn) (DSM–III). Washington, DC: APA.Google Scholar
Aylward, E., Walker, E. & Bettes, B. (1984) Intelligence in schizophrenia: meta-analysis of the research. Schizophrenia Bulletin, 10, 430459.CrossRefGoogle ScholarPubMed
Crawford, J. R. (1989) Estimation of premorbid intelligence: a review of recent developments. In Developments in Clinical and Experimental Neuropsychology (eds Crawford, J. R. & Parker, D. M.), pp. 5574. New York: Plenum.CrossRefGoogle Scholar
Crawford, J. R., Besson, J. A. O., Parker, D. M., et al (1987) Estimation of premorbid intellectual status in depression. British Journal of Clinical Psychology, 26, 313314.CrossRefGoogle ScholarPubMed
Crawford, J. R., Stewart, L. E., Garthwaite, P. H., et al (1988) The relationship between demographic variables and NART performance in normal subjects. British Journal of Clinical Psychology, 27, 181182.CrossRefGoogle ScholarPubMed
Crawford, J. R., Parker, D. M., Stewart, L. E., et al (1989) Prediction of WAIS IQ with the National Adult Reading Test: cross-validation and extension. British Journal of Clinical Psychology, 28, 267273.CrossRefGoogle Scholar
Crawford, J. R., Stewart, L. E., Cochrane, R. H. B., et al (1989) Construct validity of the National Adult Reading Test: a factor analytic study. Personality and Individual Differences, 10, 585587.CrossRefGoogle Scholar
Crawford, J. R., Allan, K. M., Besson, J. A. O., et al (1990) A comparison of the WAIS and WAIS–R in matched UK samples. British Journal of Clinical Psychology, 29, 105109.CrossRefGoogle ScholarPubMed
Crawford, J. R., Hart, S., & Nelson, H. E. (1990) Improved detection of cognitive impairment with the NART: an investigation employing hierarchical discriminant function analysis. British Journal of Clinical Psychology, 29, 239241.CrossRefGoogle ScholarPubMed
Flynn, J. R. (1984) The mean IQ of Americans: massive gains 1932–1978. Psychological Bulletin, 95, 2951.CrossRefGoogle Scholar
Flynn, J. R. (1987) Massive IQ gains in 14 nations: what IQ tests really measure. Psychological Bulletin, 101, 271291.Google Scholar
Hart, S., Smith, D. M. & Swash, M. (1986) Assessing intellectual deterioration. British Journal of Clinical Psychology, 25, 119124.CrossRefGoogle ScholarPubMed
Lea, M. (1986) A British Supplement to the Wechsler Adult Intelligence Scale – Revised. Windsor: NFER-Nelson Google Scholar
Lezak, M. D. (1983) Neuropsychological Assessment (2nd edn). New York: Oxford University Press.Google Scholar
Lubin, A., Girsekino, C. & Williams, H. (1962) Direct measurement of cognitive deficit in schizophrenia. Journal of Consulting Psychology, 26, 139143.Google Scholar
Nebes, R. D., Martin, D. C. & Horn, L. C. (1984) Sparing of semantic memory in Alzheimer's disease. Journal of Abnormal Psychology, 93, 321330.CrossRefGoogle ScholarPubMed
Nelson, H. E. (1982) National Adult Reading Test (NART): Test Manual. Windsor: NFER-Nelson.Google Scholar
Nelson, H. E. & O'Connell, A. (1978) Dementia: the estimation of premorbid intelligence levels using the new adult reading test. Cortex, 14, 234244.Google Scholar
O'Carroll, R. E. (1987) The inter-rater reliability of the National Adult Reading Test (NART): a pilot study. British Journal of Clinical Psychology, 26, 229230.Google Scholar
Office of Population Censuses and Surveys (1980) Classification of Occupations. London: HMSO.Google Scholar
Rappaport, S. & Webb, W. (1950) An attempt to study intellectual deterioration by premorbid and psychotic testing. Journal of Consulting Psychology, 14, 9598.CrossRefGoogle Scholar
Saville, P. (1977) A British Supplement to the Manual of the Wechsler Adult Intelligence Scale. Windsor: NFER-Nelson.Google Scholar
Schwartzman, A. & Douglas, V. (1962) Intellectual loss in schizophrenia. Part 1. Canadian Journal of Psychology, 16, 110.Google Scholar
Schwartzman, A. & Douglas, V. (1962) Intellectual loss in schizophrenia. Part 2. Canadian Journal of Psychology, 16, 161168.CrossRefGoogle Scholar
Wechsler, D. (1955) Manual for the Wechsler Adult Intelligence Scale. New York: Psychological Corporation.Google Scholar
Wechsler, D. (1981) Manual for the Wechsler Adult Intelligence Scale - Revised. New York: Psychological Corporation.Google Scholar
Submit a response

eLetters

No eLetters have been published for this article.