Myths of neuropsychology: intelligence, neurometabolism, and cognitive ability.
Recently, Dodrill (1999) revised a previously described "Myth of neuropsychology" (1997) to state: "Just as below average performances on neuropsychological tests are found when intelligence is below average, to that same degree above average performances on neuropsychological tests are expected when intellectual abilities are above average." This study addresses the relationship between intellectual and neuropsychological performance in the context of Magnetic Resonance Spectroscopy (MRS) measurements of the neurometabolite N-acetylaspartate (NAA). When subjects were stratified by Full Scale IQ (Average, High Average, Superior) they differed significantly in terms of total neuropsychological performance [F(2,47) = 17.63; p <.001] and the neuronal marker NAA [F(2,47) = 3.25; p <.05]. Regression analysis across groups demonstrated that FSIQ and NAA were independently related to Total z-score [F(1,47) = 29.43; p <.0001] and accounted for over half the variance (r(2) of model =.56). The concurrent relationship of FSIQ and NAA to total neuropsychological performance suggests that the relationship between measures sensitive to intellectual ability and neuropsychological performance is real, and does not reflect arbitrary psychometric or scaling properties of the WAIS-III.
Clinical and Magnetic Resonance Research Center, Department of Psychology, University of New Mexico, Albuquerque 87131, USA. rjung@lizard.unm.edu
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Jung
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Yeo
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Chiulli
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Sibbitt
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Brooks
D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D007360:Intelligence; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011594:Psychometrics; D014888:Wechsler Scales
D001224:Aspartic Acid; C000179:N-acetylaspartate