Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-23T06:31:51.810Z Has data issue: false hasContentIssue false
  • English
  • Français

Low IQ scores in schizophrenia: primary or secondary deficit?

Published online by Cambridge University Press:  24 June 2014

M. van Beilen ,
F. Withaar ,
A. H. van Zomeren  and
R. van den Bosch
M. van Beilen*
Affiliation:
Psychosencluster, Assen, the Netherlands
F. Withaar
Affiliation:
Psychosencluster, Assen, the Netherlands
A. H. van Zomeren
Affiliation:
Department of Neuropsychology, Academic Hospital of Groningen, the Netherlands
R. van den Bosch
Affiliation:
Department of Psychiatry, Academic Hospital of Groningen, the Netherlands
*
Psychosencluster, GGZ-Drenthe, Dennenweg 9, Postbus 30007, 9400 RA, Assen, the Netherlands. Tel. 0592334495, E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Background:

Schizophrenia is consistently associated with lower IQ compared to the IQ of control groups, or estimated premorbid IQ. It is not likely that the IQ scores deteriorate during the prodromal phase or first psychotic episode; they are already present before the onset of the prodromal phase and have been detected in childhood.

Methods:

We investigated cognitive functioning and IQ levels in a group of 36 patients with schizophrenia or other psychotic disorders.

Results:

The IQ scores in our sample were lower than average. The IQ showed a relation with attention, memory, speed of information processing and some aspects of executive functioning. However, when IQ scores were corrected for processing speed, they were no longer below average.

Conclusions:

These findings are important in considering the value of intelligence levels in schizophrenia. IQ scores should be judged in combination with cognitive functioning and school career to assess a patients capabilities in society. Cognitive functions and other variables might have a considerable influence on IQ scores. This rises the question of whether the low IQ scores are a primary or secondary deficit. Schizophrenia patients may have normal IQs, but could be less capable of making an IQ-test.

Keywords

cognitive functionsintelligenceschizophreniaspeed of information processing
Type
Original Article
Information
Acta Neuropsychiatrica , Volume 14 , Issue 3 , June 2002 , pp. 106 - 110
Copyright
Copyright © Acta Neuropsychiatrica 2002

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

Aylward, E, Walker, E, Bettes, B. Intelligence in schizophrenia: a meta-analysis of the research. Schizophr Bull 1984;10: 430–459.CrossRefGoogle Scholar
Goldberg, TE, Gold, JM, Greenberg, Ret al. Contasts between patients with affective disorders and patients with schizophrenia on a neuropsychological test battery. Am J Psychiatry 1993;150: 1355–1362.Google Scholar
Gilvarry, C, Takei, N, Russell, A, Rushe, T, Hemsley, D, Murray, RM. Premorbid IQ in patients with functional psychosis and their first-degree relatives. Schizophr Res 2000;41: 417–429.CrossRefGoogle ScholarPubMed
Heinrichs, RW, Zakzanis, KK. Neurocognitive deficit in schizophrenia: a quantitative review of the evidence. Neuropsychology 1998;12: 426–445.CrossRefGoogle Scholar
Russel, AJ, Munro, JC, Jones, PB, Hemsley, DR, Murray, RM. Schizophrenia and the myth of intellectual decline. Am J Psychiatry 1997;154: 635–639.Google Scholar
McGlashan, H. Early detection and intervention of schizophrenia: rationale and research. Br J Psychiatry 1998;172: 3–6. Google ScholarPubMed
Ott, SL, Spinelli, S, Rock, Det al. The New York High Risk Project: social and general intelligence in children at risk for schizophrenia. Schizophr Res 1998;31: 1–11.CrossRefGoogle ScholarPubMed
Jones, P, Rodgers, B, Murray, RM, Marmot, M. Child development risk factors for adult schizophrenia in the British 1946 birth cohort. Lancet 1994;344: 1398–1402.CrossRefGoogle ScholarPubMed
Crow, TJ, Done, DJ, Sacker, A. Childhood precursors of psychosis as clues to its evolutionary origins. Eur Arch Psychiatr Clin Neurosci 1995;245: 61–69. CrossRefGoogle ScholarPubMed
David, AS, Malmberg, A, Brandt, L, Allebeck, P, Lewis, G. IQ and risk for schizophrenia: a population-based cohort study. Psychol Med 1997;27: 1311–1323.CrossRefGoogle ScholarPubMed
David, AS. Intelligence in schizophrenia[Editorial]. Acta Psychiatr Scand 1999;100:1–2. Google Scholar
Isohanni, I, Järvelin, MR, Jones, P, Jokelainen, J, Isohanni, M. Can excellent school performance be a precursor of schizophrenia? A 28-year follow-up in the Northern Finland 1966 birth cohort. Acta Psychiatr Scand 1999;100: 17–26.CrossRefGoogle ScholarPubMed
Frith, C. Neuropsychology of schizophrenia, what are the implications of intellectual and experimental abnormalities for the neurobiology of schizophrenia? Br Med Bull 1996;52: 618–628.CrossRefGoogle Scholar
Frith, C, Dolan, RJ. Images of psychopathology. Curr Opinion Neurobiol 1998;8: 259–262. CrossRefGoogle Scholar
Bedwell, JS, Keller, B, Smith, AK, Hamburger, S, Kumra, S, Rapoport, JL. Why does post-psychotic IQ decline in child-onset schizophrenia? Am J Psychiatry 1999;156: 1996–1997.Google Scholar
Gard, D, Harrell, EH, Poreh, A. Cognitive deficits in schizophrenia on the WAIS-R NI Sentence Arrangemant Subtest: Wechsler Adult Intelligent Scale-Revised Neuropsychological Inventory. J Clin Psychol 1999;55: 1085–1094.3.0.CO;2-G>CrossRefGoogle Scholar
Luteijn, F, Van Der Ploeg, FAE. Groninger Intelligentie test: handleiding. Groningen: Swets & Zeitlinger, 1983. Google Scholar
Saan, RJ, Deelman, BG. De 15-WoordenTests A en B (een voorlopige handleiding). Groningen: Afdeling neuropsychologie AZG (intern publication), 1986. Google Scholar
Wilson, BA, Cockburn, J, Baddeley, A. The Rivermead behavioral memory test. Reading, UK: Thames Valley Test Co., Suffolk, England. Gaylord, MI: National Rehabilitation Services, 1985.Google Scholar
Rey, A. L'examen psychologique dans les cas d'encéphalopathie traumatique. Arch Psychologie 1941;28: 286–340. Google Scholar
Wechsler, D. The measurement of adult intelligence. Baltimore: Williams & Wilkins, 1970. Google Scholar
Van den Bosch, RJ, Rombouts, RP, Asma, MJ. What determines continuous performance task performance? Schizophr Bull 1996;22: 643–651.CrossRefGoogle ScholarPubMed
Stroop, JR. Studies of interference in serial verbal reactions. J Exp Psychol 1935;18: 643–662. CrossRefGoogle Scholar
Reitan, RM. Validity of the trailmaking test as an indicator of organic braindamage. Percept Motor Skills 1958;8: 271–276. CrossRefGoogle Scholar
Heaton, RK. Wisconsin card sorting test manual. Odessa, WI: Psychological Assessment Resources, 1981. Google Scholar
Shallice, T. Specific impairments of planning. Phil Trans R Soc Lond 1982;298: 199–209. CrossRefGoogle ScholarPubMed
Braff, DL. Impaired speed of information processing in non medicated schizotypical patients. Schizophr Bull 1981;7: 499–508.CrossRefGoogle Scholar
Braff, DL, Sacuzzo, DP. Iformation processing deficit in paranoid schizophrenia: a two-factor deficit. Am J Psychiatry 1981;138: 1051–1056.Google Scholar
Braff, DL, Sacuzzo, DP. Effect of antipsychotic medication on speed of information processing in schizophrenic patients. Am J Psychiatry 1982;139: 1127–1130.Google ScholarPubMed
Sweitzer, RKR, Lee, M. Use of speed accuracy trade-off to charactarize information processing in schizophrenics and normals. Psychopathology 1992;25: 29–40.CrossRefGoogle Scholar
Weiss, KM. Clinical assessment of attention in schizophrenia. Psychiatr Res 1996;29: 147–154. CrossRefGoogle Scholar
Riley, EM, McGovern, D, Mockler, Det al. Neuropsychological functioning in first-episode psychosis- evidence of specific deficits. Schizophr Res 2000;43: 47–55.CrossRefGoogle ScholarPubMed
Krabbendam, L, Marcelis, M, Delespaul, P, Jolles, J, van Os, J. Single or multiple familial cognitive risk factors in schizophrenia? Am J Med Gen 2001;105: 183–188. CrossRefGoogle ScholarPubMed