Relationships between factors of intelligence and brain volume

ArticleinPersonality and Individual Differences 29(6):1095-1122 · December 2000with 83 Reads
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Abstract
The recent explosion of studies aimed at determining the biological basis of intelligence has revealed that cognitive ability has a strong biological substrate. This study expands on this literature by examining the relation between cognitive ability and MRI-measured brain volume and head size in a sample of adult male siblings recruited from the London, Ontario community in Canada. It was found that brain volume correlated with IQ at 0.35 (P<0.01), thus replicating the results of past studies. Corrections for restriction of range and attenuation in both this and past studies suggest that the population value of the brain volume-IQ correlation is closer to 0.50. Head size variables, with one exception, also showed the expected positive correlations with IQ. The results of a vector analysis on factor scores indicated that the more highly g-loaded a test was the more highly it correlated with brain volume (r=0.59, P<0.01). The sum of the data suggested that although brain volume (and to a lesser extent, head size) is predictive of g, fluid ability, and memory, it does not predict crystallized ability. Unexpectedly, the higher the spatial imaging loading of a test, the less its correlation with brain volume (vector correlation=−0.84, P<0.001).

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    Purpose: Dietary nucleotides are thought to be conditionally essential nutrients in infancy. However, studies have reported inconsistent findings regarding the association between nucleotide supplementation and infant physical growth. We conducted this meta-analysis to examine the efficacy of nucleotide supplementation of infant formula in promoting early infant growth. Methods: Randomized controlled trials that evaluated the association between nucleotide supplementation and infant growth through June 2017 were included. Study quality was assessed using the Cochrane Collaboration's Risk of Bias tool. Standardized mean differences (SMD) with 95% confidence intervals (CIs) were calculated. Heterogeneity was assessed using Q and I2tests. Results: Nucleotide supplementation significantly increased the rate of weight gain (SMD 0.26; 95% CI 0.06-0.47), but had no effect on weight (SMD - 0.16; 95% CI - 0.55-0.23), weight Z score (SMD, - 0.42; 95% CI - 1.64-0.81), length (SMD 0.01; 95% CI - 0.18-0.21) and length Z score (SMD 0.15; 95% CI - 0.10-0.40). Occipitofrontal head circumference (OFC) at 7-8 weeks (SMD 0.30; 95% CI 0.10-0.50) and the rate of OFC gain (SMD 0.34; 95% CI 0.09-0.58) were significantly improved with nucleotide supplementation, whereas, 16- and 20-week OFC values did not differ. Conclusions: Our meta-analysis indicated that nucleotide supplementation can increase the rate of weight gain, OFC and rate of OFC gain; however, we cannot conclude that it affects weight, weight Z score, length or length Z score. Large-scale randomized controlled trials of long-term nucleotide supplementation are needed to reach definitive conclusions.
  • Chapter
    De persoonlijkheid van mensen speelt een cruciale rol in hun functioneren en hun psychisch en lichamelijk welzijn. Dat maakt het onderwerp relevant voor elke (aanstaande) professional die met mensen werkt. In zeven hoofdstukken krijgt de lezer inzicht in allerlei aspecten van de persoonlijkheid. Daarbij wordt antwoord gegeven op vragen als: 'Wat is persoonlijkheid en waar wordt deze door bepaald?', 'Welke persoonlijkheidseigenschappen kunnen we onderscheiden?' en 'Hoe hangen deze eigenschappen samen met bijvoorbeeld de culturele achtergrond van mensen, hun sociale relaties, hun intelligentie en hun prestaties op de werkvloer?' Ook wordt aandacht besteed aan het meten van persoonlijkheid en intelligentie. Ten slotte wordt ingegaan op de wijze waarop, in begeleiding en therapie, aandacht besteed kan worden aan problemen en stoornissen die samenhangen met de persoonlijkheid. De vele opdrachten, voorbeelden en casussen maken het mogelijk om de opgedane theoretische kennis in de praktijk toe te passen. Op de website bij het boek, www.persoonlijkheidspsychologie.nl, zijn oefenopdrachten te vinden, links naar informatieve filmpjes en extra materiaal. Inleiding in de persoonlijkheidspsychologie is bestemd voor bachelor- en masteropleidingen in de sociale sector, zoals (toegepaste) psychologie, maatschappelijk werk en dienstverlening, sociaal pedagogische hulpverlening en pedagogiek.
  • Article
    Full-text available
    Across taxonomic subfamilies, variations in intelligence ( G ) are sometimes related to brain size. However, within species, brain size plays a smaller role in explaining variations in general intelligence ( g ), and the cause-and-effect relationship may be opposite to what appears intuitive. Instead, individual differences in intelligence may reflect variations in domain-general processes that are only superficially related to brain size.
  • Article
    Full-text available
    A substantial amount of empirical research has estimated the association between brain volume and intelligence. The most recent meta-analysis (Pietschnig, Penke, Wicherts, Zeiler, & Voracek, 2015) reported a correlation of .24 between brain volume and intelligence – notably lower than previous meta-analytic estimates. This headline meta-analytic result was based on a mixture of samples (healthy and clinical) and sample correlations not corrected for range restriction. Additionally, the role of IQ assessment quality was not considered. Finally, evidential value of the literature was not formally evaluated. Based on the results of our meta-analysis of the Pietschnig et al.'s sample data, the corrected correlation between brain volume and intelligence in healthy adult samples was r = .31 (k = 32; N = 1758). Furthermore, the quality of intelligence measurement was found to moderate the effect between brain volume and intelligence (b = .08, p = .028). Investigations that used ‘fair’, ‘good’, and ‘excellent’ measures of intelligence yielded corrected brain volume and intelligence correlations of .23 (k = 9; N = 547), .32 (k = 10; N = 646), and .39 (k = 13; N = 565), respectively. The Henmi/Copas adjusted confidence intervals, the p-uniform results, and the p-curve results failed to suggest evidence of publication bias and/or p-hacking. The results were interpreted to suggest that the association between in vivo brain volume and intelligence is arguably best characterised as r ≈ .40. Researchers are encouraged to consider intelligence measurement quality in future meta-analyses, based on the guidelines provided in this investigation.
  • Chapter
    A recent line of research in economics and psychology hypothesizes that differences in national average intelligence, proxied by IQ tests, are important drivers of national economic outcomes. Cross-country regressions, while showing a robust IQ-growth relationship, cannot fully test this hypothesis. Thus, recent work explores the micro-foundations of the IQ-productivity relationship. The well-identified psychological relationship between IQ and patience implies higher savings rates and higher folk theorem-driven institutional quality in high average IQ countries. Experiments indicate that intelligence predicts greater pro-social behavior in public goods and prisoner’s dilemma games, supporting the hypothesis that high national average IQ causes higher institutional quality. High average IQ countries also have higher savings intensity by a variety of measures. Other possible IQ-productivity channels are discussed, as are possible environmental causes of differences in national average IQ.
  • Chapter
    Since its publication in 1984, Jackson’s Multidimensional Aptitude Battery (MAB) has been used quite extensively in a variety of programs of research. In this chapter, the MAB and its psychometric properties are first described, followed by sections illustrating different types of research that the MAB has been used in. As will be seen, the MAB has allowed considerable advances to be made in investigations of such topics as relationships between intelligence and speed of information-processing; behavioral genetic studies of cognitive abilities; the identification of biological correlates of human intelligence; a study of both the phenotypic and the genetic relationship between intelligence and dimensions of personality; and a study of environmental factors that contribute to the differential personality development of twins and non-twin siblings. It is not claimed that none of these investigations could have been conducted without the MAB, however the existence of the MAB has certainly contributed to the ability of researchers to obtain valid estimates of broad dimensions of intelligence from large samples of people much more quickly and easily than would be the case if they had had to employ an individually-administered IQ test such as the Wecshler or Binet.
  • Chapter
    Full-text available
    Intelligentie Het aantal eigenschappen waarop mensen van elkaar verschillen is groot. In dit boek staan tot nu toe vooral persoonlijkheidseigenschappen als extra versie, neuroticisme en dergelijke centraal die een persoon uniek maken. Mensen ver-schillen uiteraard ook op andere eigenschappen. Zo is de een goed in sport en de ander meer vaardig in kunstzinnige uitingen als muziek of schilderen. We weten ook dat sommigen intelligenter zijn dan anderen, beter spreken in het openbaar, beter kunnen rekenen of sneller een probleem kunnen oplossen waarmee ze plots worden geconfronteerd. In dit hoofdstuk staan we stil bij de vraag of de verschillen in intellectuele eigen-schappen verband houden met persoonlijkheidseigenschappen. Er zal eerst stil worden gestaan bij de vraag wat intelligentie is en waarom dit in een boek over persoonlijkheid aan de orde komt. Daarna wordt intelligentie in een historisch perspectief gedefinieerd, om uiteindelijk te komen tot een beschrijving van de huidige visie op intelligentie. Vervolgens wordt aandacht besteed aan de biolo-gische basis van intelligentie, wordt beschreven op welke wijze intelligentie kan worden onderzocht in psychologisch onderzoek en wordt een overzicht gegeven van de meest gebruikte intelligentietests in Nederland. Ten slotte wordt nog specifiek ingezoomd op de intelligentie van een aantal specifieke groepen. 6.1 Wat is intelligentie? Intelligentie is een concept waar heel veel verschillende betekenissen aan worden gegeven. In het dagelijks leven gaan veel mensen ervan uit dat het onderscheid maakt tussen slimme en minder slimme mensen en veronder stellen we dat intelligente mensen beter kunnen leren en meer succes zullen hebben in het uitoefenen van hun beroep. Ook vinden we dat sommige diersoorten intelligent gedrag kunnen vertonen. Zo gebruiken mensapen als bonobo's stokjes als instrument bij het eten van termieten uit een termietenheuvel, en vinden we huisdieren soms slim als zij een balletje in de struiken weten terug te vinden. In televisieseries worden dieren als honden, paarden of dolfijnen als intelli-gente helden afgebeeld. In 1955 wordt de term artificiële intelligentie voor het eerst gebruikt om aan te geven dat ook machines intelligent gedrag kunnen vertonen. Doorgaans worden daar natuurlijk computers mee bedoeld, maar de laatste jaren worden ook relatief eenvoudige huishoudelijke apparaten uitgerust met een chip en functioneren ze in alledaagse communicatie intelligent. Maar
  • Article
    The findings from several authors confirm that undernutrition at an early age affects brain growth and intellectual quotient. Most part of students with the lowest scholastic achievement scores present suboptimal head circumference (anthropometric indicator of past nutrition and brain development) and brain size. On the other hand, intellectual quotient measured through intelligence tests (Weschler-R, or the Raven Progressives Matrices Test) has been described positively and significantly correlated with brain size measured by magnetic resonance imaging (MRI); in this respect, intellectual ability has been recognized as one of the best predictors of scholastic achievement. Considering that education is the change lever for the improvement of the quality of life and that the absolute numbers of undernourished children have been increasing in the world, is of major relevance to analyse the long-term effects of undernutrition at an early age. The investigations related to the interrelationships between nutritional status, brain development, intelligence and scholastic achievement are of greatest importance, since nutritional problems affect the lowest socioeconomic stratum with negative consequences manifested in school-age, in higher levels of school dropout, learning problems and a low percentage of students enrolling into higher education. This limits the development of people by which a clear economic benefit to increase adult productivity for government policies might be successful preventing childhood malnutrition.
  • Article
    Full-text available
    The structure and function of the human brain is closely related to cognitive processes of the mind and physiological processes of the body, suggesting that an intricate relationship exists between cognitive health, body health, and underlying neural architecture. In the current study, morphometric differences in cortical and subcortical gray matter regions, white matter integrity, and resting-state functional connectivity was assessed to determine what combinations of neural variables best explain an interconnected behavioral relationship between body mass index (BMI), general intelligence, and specific measures of executive function. Data for 82 subjects were obtained from the Nathan Kline Institute Rockland Sample. Behavioral results indicated a negative relationship between BMI and intelligence, which exhibited mediation by an inhibitory measure of executive function. Neural analyses further revealed generally contrasting associations of BMI, intelligence, and executive function with cortical morphometric regions important for inhibitory control and directed attention. Moreover, BMI related to morphometric alterations in components of a frontolimbic network, namely reduced thickness in the anterior cingulate cortex and ventromedial prefrontal cortex, whereas intelligence and inhibitory control primarily related to increased thickness and volume in parietal regions, as well as significantly increased across-network connectivity of visual and default mode resting-state networks. These results propose that medial prefrontal structure and interconnected frontolimbic and frontoparietal networks are important to consider in the relationship between BMI, intelligence, and executive function.
  • Article
    Positive associations between human intelligence and brain size have been suspected for more than 150 years. Nowadays, modern non-invasive measures of in vivo brain volume (Magnetic Resonance Imaging) make it possible to reliably assess associations with IQ. By means of a systematic review of published studies and unpublished results obtained by personal communications with researchers, we identified 88 studies examining effect sizes of 148 healthy and clinical mixed-sex samples (> 8,000 individuals). Our results showed significant positive associations of brain volume and IQ (r=.24, R(2)=.06) that generalize over age (children vs. adults), IQ domain (full-scale, performance, and verbal IQ), and sex. Application of a number of methods for detection of publication bias indicates that strong and positive correlation coefficients have been reported frequently in the literature whilst small and non-significant associations appear to have been often omitted from reports. We show that the strength of the positive association of brain volume and IQ has been overestimated in the literature, but remains robust even when accounting for different types of dissemination bias, although reported effects have been declining over time. While it is tempting to interpret this association in the context of human cognitive evolution and species differences in brain size and cognitive ability, we show that it is not warranted to interpret brain size as an isomorphic proxy of human intelligence differences.
  • Article
    The relationship between IQ and fertility was examined at the state level within the USA. As predicted, SAT-derived state IQ scores were negatively correlated with three different indicators of state fertility rates. The IQ-fertility relationship remained relatively unchanged when demographic and educational characteristics of the states were controlled for. Limitations and possible causal hypotheses are discussed.
  • Article
    In Section 1, I introduce three views that explain human cognitive development from different standpoints: Marcus’s neo-nativism, standard neuroconstructivism, and neo-neuroconstructivism. In Section 2, I assess Marcus’s attempt to reconcile nativism with developmental flexibility. In Section 3, I argue that in structurally reconfiguring nativism, Marcus ends up transforming it into an unrecognizable form, and I claim that his view (neo-nativism) could be accommodated within the more general framework provided by standard neuroconstructivism. In Section 4, I focus on recent empirical findings in neuropsychology and cultural/social neuroscience, and propose a friendly revision to standard neuroconstructivism, thus developing the neo-neuroconstructivist view. I conclude the article in Section 5 by analysing the implications of the results discussed in Section 4 for both neo-nativism and standard neuroconstructivism. 1 Introduction 2 Marcus’s Neo-nativism 3 Is Marcus’s Neo-nativism Really a Form of Nativism? 4 Neo-neuroconstructivism and Dynamic Enskillment 5 Conclusion
  • Article
    In 1992, Reed and Jensen [Intelligence 16 (1992) 259–272] reported a positive correlation (.26; p=.002; .37 after correcting for restricted intelligence range) between a brain nerve conduction velocity (NCV) and intelligence level in 147 normal male students. In the first follow-up of their study, we report on a study using similar NCV methodologies, but testing both male and female students and using more extensive measures of cognitive abilities. One-hundred eighty-six males and 201 females, aged 18–25 years, were tested in three different NCV conditions and with nine cognitive tests, including Raven Progressive Matrices as used by Reed and Jensen. None of the 27 independent correlations in either the males or in the females are significant at Bonferroni-corrected probability levels, but 25 of 27 correlations in males and 20 of 27 correlations in females have positive signs. The exact binomial probabilities for these results are 5.6×10−6 and .002, respectively. We discuss possible reasons for the differences between the results of Reed and Jensen and our results. We also find that males have four percent faster NCVs than females with each of the three test conditions, probably due to their faster increase of white matter in the brain during adolescence.
  • Article
    Although the black and white populations in the United States differ, on average, by about one standard deviation (equivalent to 15 IQ points) on current IQ tests, they differ by various amounts on different tests. The present study examines the nature of the highly variable black–white difference across diverse tests and indicates the major systematic source of this between-population variation, namely, Spearman's g. Charles Spearman originally suggested in 1927 that the varying magnitude of the mean difference between black and white populations on a variety of mental tests is directly related to the size of the test's loading on g, the general factor common to all complex tests of mental ability. Eleven large-scale studies, each comprising anywhere from 6 to 13 diverse tests, show a significant and substantial correlation between tests' g loadings and the mean black–white difference (expressed in standard score units) on the various tests. Hence, in accord with Spearman's hypothesis, the average black–white difference on diverse mental tests may be interpreted as chiefly a difference in g, rather than as a difference in the more specific sources of test score variance associated with any particular informational content, scholastic knowledge, specific acquired skill, or type of test. The results of recent chronometric studies of relatively simple cognitive tasks suggest that the g factor is related, at least in part, to the speed and efficiency of certain basic information-processing capacities. The consistent relationship of these processing variables to g and to Spearman's hypothesis suggests the hypothesis that the differences between black and white populations in the rate of information processing may account for a part of the average black–white difference on standard IQ tests and their educational and occupational correlates.
  • Magnetic resonance brain images in schizophrenic and normal subjects: In¯uence of diagnosis and education Head circumference, biparietal diameter and brain growth in fetal and postnatal life
    • M K Demyer
    • R L Gilmor
    • H C Hendrie
    • W E Demyer
    • G T Augustyn
    • R K Jackson
    • J Dobbing
    • J Sands
    DeMyer, M. K., Gilmor, R. L., Hendrie, H. C., DeMyer, W. E., Augustyn, G. T., & Jackson, R. K. (1988). Magnetic resonance brain images in schizophrenic and normal subjects: In¯uence of diagnosis and education. Schizophrenia Bulletin, 14, 21±32. Dobbing, J., & Sands, J. (1978). Head circumference, biparietal diameter and brain growth in fetal and postnatal life. Early Human Development, 2, 81±87.
  • Intelligence and brain structure in normal individuals Occipitofrontal head circumference Ð an accurate measure of intracranial volume
    • N C Andreasen
    • M Flaum
    • V Swayze Ii
    • O Leary
    • D S Alliger
    • R Cohen
    • G Ehrhardt
    • J Yuh
    • ±134 J C Wickett
    Andreasen, N. C., Flaum, M., Swayze II, V., O'Leary, D. S., Alliger, R., Cohen, G., Ehrhardt, J., & Yuh, W. T. C. (1993). Intelligence and brain structure in normal individuals. American Journal of Psychiatry, 150, 130±134. J.C. Wickett et al. / Personality and Individual Di€erences 29 (2000) 1095±1122 Bray, P. F., Shields, W. D., Wolcott, G. J., & Madsen, J. A. (1969). Occipitofrontal head circumference Ð an accurate measure of intracranial volume. Journal of Pediatrics, 75, 303±305. Castellanos, F. X., Giedd, J. N., Eckburg, P., Marsh, W. L., Vaituzis, A. C., Kaysen, D., Hamburger, S. D., & Rapoport, J. L. (1994). Quantitative morphology of the caudate nucleus in attention de®cit hyperactivity disorder. American Journal of Psychiatry, 151, 1791±1796.
  • Handbook for the individual or group culture-fair intelligence test: scale 2
    • R B Cattell
    • A K S Cattell
    Cattell, R. B., & Cattell, A. K. S. (1973). Handbook for the individual or group culture-fair intelligence test: scale 2. Champaign, IL: IPAT.
  • Brain size and cognitive ability: Correlations with age, sex, social class, and race The association between intelligence level and brain volume measures: A negative ®nding
    • J P Rushton
    • C D Ankney
    Rushton, J. P., & Ankney, C. D. (1996). Brain size and cognitive ability: Correlations with age, sex, social class, and race. Psychonomic Bulletin and Review, 3, 21±36. Teasdale, T. W., & Pakkenberg, B. (1988). The association between intelligence level and brain volume measures: A negative ®nding. Scandinavian Journal of Psychology, 29, 123±125.
  • Cerebral ventricle dimensions as risk factors for schizophrenia and a€ective psychosis: An epidemiological approach to analysis The advantage of being broad minded: Brain diameter and neuropsychological test performance in elderly war veterans
    • P B Jones
    • I Harvey
    • S W Lewis
    • B K Toone
    • J Van Os
    • M Williams
    • R M Murray
    • ±1011 Jorm
    • A F Creasey
    • H Broe
    • G A Sulway
    • M R Kos
    • S C Dent
    Jones, P. B., Harvey, I., Lewis, S. W., Toone, B. K., Van Os, J., Williams, M., & Murray, R. M. (1994). Cerebral ventricle dimensions as risk factors for schizophrenia and a€ective psychosis: An epidemiological approach to analysis. Psychological Medicine, 24, 995±1011. Jorm, A. F., Creasey, H., Broe, G. A., Sulway, M. R., Kos, S. C., & Dent, O. F. (1997). The advantage of being broad minded: Brain diameter and neuropsychological test performance in elderly war veterans. Personality and Individual Di€erences, 23, 371±377.
  • Der Zahlen±Verbindungs-Test (ZVT)
    • W D Oswald
    • E Roth
    Oswald, W. D., & Roth, E. (1978). Der Zahlen±Verbindungs-Test (ZVT). Gottingen, Germany: Hogrefe.
  • Physiological correlates of human intelligence. Unpublished master's thesis
    • J C Wickett
    Wickett, J. C. (1992). Physiological correlates of human intelligence. Unpublished master's thesis, University of Western Ontario.
  • Neuropsychology test procedures
    • D Kimura
    Kimura, D. (1986). Neuropsychology test procedures. London, ON: DK Consultants.
  • Article
    New data are presented comparing the functioning of brain damaged children and their matched controls on comprehensive measures of adaptive functioning. These data build toward the development of practically useful children's neuropsychological assessment batteries. Some comparative data are also presented on impaired groups of special interest: children defined as suffering minimal brain dysfunction, epileptics, and mentally retarded individuals. Data on some recent developments in the field are summarized with implications for further development of neuropsychological assessment procedures, and for the solution of as yet unsolved clinical problems. Clinically useful descriptive information about the nature of the tests and batteries reported in the various chapters and scores for various normal and impaired groups on these variables are included. As a special feature of this volume, the authors have included clinical examples at the end of many of the chapters in order to illustrate application of research results; the gulf between research findings and clinical application often is immense. The purpose in giving case examples is to add some richness to the research findings and to help bridge the gap between research and clinical application.
  • Article
    Using data from magnetic resonance imaging (MRI), autopsy, endocranial measurements, and other techniques, we show that (1) brain size is correlated with cognitive ability about .44 using MRI; (2) brain size varies by age, sex, social class, and race; and (3) cognitive ability varies by age, sex, social class, and race. Brain size and cognitive ability show a curvilinear relation with age, increasing to young adulthood and then decreasing; increasing from women to men; increasing with socioeconomic status; and increasing from Africans to Europeans to Asians. Although only further research can determine if such correlations represent cause and effect, it is clear that the direction of the brain-size/cognitive-ability relationships described by Paul Broca (1824-1880), Francis Galton (1822-1911), and other nineteenth-century visionaries is true, and that the null hypothesis of no relation, strongly advocated over the last half century, is false.
  • Article
    The current paper corrects some previously published results (Egan, Chiswick, Santosh, Naidu, Rimmington & Best, Personality and Individual Differences, 17, 357–367, 1994), and suggests that the range-corrected correlation between total brain volume and Full-Scale IQ, controlling for height and weight, is 0.48. not 0.66. This result replicates correlations of similar sizes found by researchers from four different research teams. The high correlation between CSF volume and IQ measures in this study is discussed in reference to the method of estimating CSF volume. It is suggested that an automated method may have provided an indirect measure of brain surface area. Finally, by simulating the range of possible partial correlations between brain volume and intelligence controlling for height and weight, it is argued that the correlation between brain volume and measures of IQ is only modestly affected by correction for body size. As such, brain volume/IQ coefficients should only be corrected for body size if data from the specific study warrants such a procedure.
  • Article
    The study aimed to find out if brain width and anteroposterior (AP) diameter are related to neuropsychological test performance. Computerized tomography (CT) scans and neuropsychological testing were carried out on 201 elderly veterans of World War II, half of whom were former prisoners of war (POWs). Brain width and AP diameter were measured at the level of the third ventricle. Brain width was related to performance on tests of verbal ability and to education, but AP diameter was unrelated to any of the tests. These results held whether or not demented Ss were excluded, and whether or not the effect of body size was partialled out. The former POWs did not differ on brain width or any of the neuropsychological tests, but they had a shorter mean AP diameter. This difference may be due to selective survival under conditions of starvation. An unexpected finding was that extraversion was related to brain width independent of verbal ability. The relationship of brain width to verbal ability and education may be relevant to hypotheses that education and brain size are protective for dementia.
  • Article
    Magnetic resonance imaging (MRI) and neuropsychological tests were administered to 68 patients with schizophrenia and 68 healthy controls. MRIs were analyzed with a partially automated segmentation method that quantifies the volume of each cerebral hemisphere and its cerebrospinal fluid (CSF). Whereas patients had higher ventricular-brain ratio (VBR), ventricular CSF (vCSF) volume was equivalent to controls. Brain volume was lower. Cognitive function did not correlate with VBR or vCSF volume in either group, but cognitive function did correlate with brain volume. Divided as deficit (DF) and nondeficit (NDF), only DF patients had lower brain volume than controls. Whereas NDF patients showed little correlation between anatomy and cognitive function, there were more correlations between brain volume and cognition in DF patients. Changes in DF/NDF subtype with time and treatment reduced the significance of these findings. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
  • Article
    In this chapter, 4 approaches to the investigation of biological correlates of intelligence are described covering (1) anatomical or structural head size and brain volume estimates, (2) psychophysiological event-related potentials, (3) nerve conduction velocity, and (4) cerebral glucose metabolic rates. The goals of this chapter are threefold. First, to illustrate that a number of anatomical and physiological correlates of intelligence have been identified and replicated sufficiently often to be considered reliably established. A second goal, was to show that not all measures that have been claimed to be biological correlates of intelligence have met with similar replicability or consistency of results. The third goal was to stress the need for the further development of theories regarding the functional significance of biological correlates of intelligence and for future research into this area to be more theoretically driven. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
  • Article
    In an attempt to examine the relationship between neural speed, as indicated by nerve conduction velocity (NCV) along the median nerve of the arm, and intelligence, four relevant studies have been carried out: two finding the relationship and two not finding evidence of such a relationship. In an attempt to replicate the two studies (Vernon & Mori, 1992) finding this relationship, 38 healthy, right-handed females, aged 20 to 30 years, completed the Multidimensional Aptitude Battery (Jackson, 1984), a series of reaction-time tasks and were submitted to the same NCV procedures as in Vernon and Mori (1992). Contrary to prediction, NCV did not correlate with intelligence or reaction time. A reanalysis of Vernon and Mori (1992), however, showed evidence for a possible sex difference in relation to NCV and intelligence, with a pronounced correlation between these variables being found in males but a much smaller correlation being found in females.
  • Article
    One hundred and thirteen high school students were randomly assigned to one of two groups that were administered an intelligence test (the Multidimensional Aptitude Battery) under either timed or untimed conditions. Subsequently, all subjects were given a battery of 8 reaction time tests. Multiple regression analyses showed that combinations of RTs were approximately equally good predictors of IQ scores in both groups. Zero-order correlations between each RT test and IQ scores were also approximately equal for timed and untimed Verbal and Full-Scale scores but correlations with Performance scores were higher in the timed condition. The extent to which the different RT tests correlated with timed scores was quite highly related to the tests' loadings on a general speed factor but these loadings were not related to the tests' correlations with untimed scores. Rather, the relative complexity of the RT tests had a stronger influence on their correlations with IQ scores in the untimed condition. It is concluded that timed and untimed intelligence tests impose different information-processing demands on subjects but that the speed with which subjects can cope with these demands is equally important in both conditions.
  • Der Zahlen±Verbindungs-Test (ZVT) Handanweisung (Manual)
    • W D Oswald
    • E Roth
    Oswald, W. D., & Roth, E. (1987). Der Zahlen±Verbindungs-Test (ZVT) Handanweisung (Manual). Gottingen, Germany: Hogrefe.
  • Article
    Although brain volumes calculated from magnetic resonance (MR) imaging have been found to correlate with IQ, the relationship between MR-derived brain volume and other mental processes has not been examined. Fifty normal-ability adults had their brain volume calculated using MR scanning, along with tasks measuring IQ, memory, and information-processing speed, and an auditory evoked potential (AEP) task. All MR scans were corrected for artefacts arising from inhomogenous coil response. Of the three AEP components measured, only P3 latency and amplitude were associated with measures of mental ability. Out of the 50 adults tested, 40 had usable MR records. Corrected for height and weight, total brain volume was associated with Full-Scale IQ (r = 0.32, P < 0.025); when this correlation was corrected for restricted range, the correlation increased to 0.66. Although there was no systematic pattern of associations between brain volume and individual measures of memory or information-processing speed for the bivariate correlations, adjusted R2s from exploratory multiple regression suggested that while information-processing speed shared 7% of test variance with brain volume, memory might account for 22%, and the complete test battery might account for as much as 32%. Our study therefore suggests a partial dissociation between mechanisms underlying intelligence, in that brain volume is associated with mental ability and memory, but not especially with information-processing speed.
  • Article
    The differential effects of inbreeding on 11 subtests of the WISC, in a Japanese (Hiroshima) population, are related to the factor structure of the tests. The degree of inbreeding depression on mental abilities is most strongly correlated with the subtests' loadings on the General factor, g, which is common to all of the subtests. Loadings on the Verbal factor are also positively correlated with inbreeding depression. The (non-verbal) Performance factor, however, is slightly enhanced by inbreeding. One possible inference from these findings is that at least the General factor shows genetic dominance, which is theoretically consistent with natural selection for g in the course of human evolution. It is also noted that the factor structure of the WISC in the Japanese population is highly similar to that of the U.S. standardization sample.
  • Article
    Two studies (with sample sizes of 85 and 88) are reported that investigated relationships among measures of intelligence, speed of information processing, and peripheral nerve conduction velocity (NCV). In both studies, NCV was significantly correlated with IQ scores (rs = .42 and .48) and with reaction times (RTs; rs = −.28 and −.18): Thus, faster NCV was associated with higher IQ scores and faster speed of processing. In both studies, NCV and RTs contributed significantly, in combination, to the prediction of fullscale IQ (shrunken multiple Rs = .53 and .57), but the expected pattern of causal relationships between the variables was not borne out. The results are interpreted in terms of a “neural efficiency” model of intelligence, which has recieved support from other studies of physiological correlates of human intelligence.
  • Article
    Scores on 17 diverse tests of cognitive abilities obtained from 82 pairs of monozygotic (MZ) and 61 pairs of dizygotic (DZ) twins were correlated with head size. A general factor, or psychometric g, was extracted from the tests, and g factor scores were found to be correlated with head size variables not only within individuals, but within twin pairs and between twin pairs. The size of the various tests' g loadings predicts the degree to which the tests are correlated with head size. This finding adds one more biological variable—head size and, by inference, brain size—to the list of other biological variables reported in the literature as showing a significant relation to psychometric g, the general factor common to all cognitive tests. Also, the varying magnitude of the mean difference between groups of white and black children on the 17 tests is related to the tests' loadings on g, on spatial ability, and the tests' correlations with head size.
  • Article
    Hemispheric size asymmetry differences as assessed from MRIs of 39 healthy college students were correlated with prorated WAIS-R Verbal IQ minus Performance IQ and Vocabulary minus Block Design scores within subjects. In men, a relatively larger left hemisphere predicted better verbal than nonverbal ability, whereas in women a larger left hemisphere predicted relatively better nonverbal than verbal ability. The results were interpreted as providing evidence for sex differences in brain organization.
  • Article
    Young men and women who had made self-inspections of direction of testicular-or breast-size asymmetry, were evaluated on a battery of cognitive tests. Tests were categorized as Masculine (generally performed better by men), Feminine (better by women), or Neutral (favouring neither). Men and women with larger right sides performed relatively better on Masculine tasks, whereas those with larger left sides performed relatively better on Feminine tasks. The findings are interpreted to mean that gonadal/somatic asymmetry may be a marker of early development of certain sexually dimorphic neural systems, whether or not it directly reflects brain hemispheric asymmetry. The data suggest a significant biological contribution to intellectual pattern.
  • Article
    Volumetric measures of the brain and ventricles were derived from CT films and related to intellectual variables from the Wechsler Adult Intelligence Scale (WAIS). Subjects were patients referred for neurological examination for headache or somatic complaints, sometimes accompanied by anxiety or dysphoric affect (N = 41), for whom a comprehensive neurological work-up revealed no evidence of abnormality. The asymmetry of hemispheric volume (left minus right over total, times 100) was correlated (r = .57, p < .001) with Verbal IQ minus Performance IQ within subjects. No relationship was observed between total brain or hemispheric volumes and IQ scores. Brain and ventricular volumes were larger for the left hemisphere than the right.
  • Article
    The curves for biparietal diameter, head circumference and brain weight with increasing age have different shapes, and these differences have been explained. Interconversion procedures are suggested. One important consequence of changing growth velocities relates to assessing prognosis for catch-up following adversity. On the assumption that catch-up of brain growth must occur within the period of the brain weight growth spurt, the interpretation of head circumference charts is discussed.
  • Article
    A new paper-and-pencil test of spatial visualization was constructed from the figures used in the chronometric study of Shepard and Metzler (1971). In large samples, the new test displayed substantial internal consistency (Kuder-Richardson 20 = .88), a test-retest reliability (.83), and consistent sex differences over the entire range of ages investigated. Correlations with other measures indicated strong association with tests of spatial visualization and virtually no association with tests of verbal ability.
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    A sample of 50 DSM-III-diagnosed schizophrenics (mean age, 34 years) intentionally biased to contain a relatively high proportion of persistently unemployed persons was compared with a sample of 87 normal volunteers on three computed tomographic measures. These were lateral ventricle-brain ratio, regional brain computed tomographic density values, and brain slice area. Images were made with the same computed tomographic scanner and identical scan parameters. Computed tomographic data were assessed blindly using a computer-linked image array processor and electronic planimeter. Ventricle-brain ratios were significantly higher in schizophrenics, with 28% of the patient sample exceeding 2 SDs of the control mean. Brain area measures were not associated with an enlarged ventricle-brain ratio. Contrary to our prediction, ventricular enlargement was unassociated with most negative symptom ratings, but was correlated with the absence of positive symptoms. A history of abnormal delivery and the presence of left-handedness were significant predictors of an enlarged ventricle-brain ratio on multiple regression analysis. Schizophrenics had a significantly smaller brain slice area compared with normal controls, a finding not attributable to height differences between groups. Brain slice area was inversely correlated with computed tomographic brain density across all subjects. After correction of computed tomographic density values for area using a linear regression model, no significant regional density differences were detectable between normal controls and schizophrenics. Within normal controls there was a significant relationship between social class and brain slice area, but not ventricle-brain ratio.
  • Article
    Ratings of pre-morbid intelligence level, derived from the hospital charts of 26 chronic schizophrenics, were correlated with the post-mortem brain volume measures of cortex, white matter, central grey matter, and ventricles. Contrary to hypothesis, no significant correlations were found.
  • Article
    Volumetric measures of the brain and ventricles were derived from CT films and related to intellectual variables from the Wechsler Adult Intelligence Scale (WAIS). Subjects were patients referred for neurological examination for headache or somatic complaints, sometimes accompanied by anxiety or dysphoric affect (N = 41), for whom a comprehensive neurological work-up revealed no evidence of abnormality. The asymmetry of hemispheric volume (left minus right over total, times 100) was correlated (r = .57, p less than .001) with Verbal IQ minus Performance IQ within subjects. No relationship was observed between total brain or hemispheric volumes and IQ scores. Brain and ventricular volumes were larger for the left hemisphere than the right.
  • Article
    Brain weight at the time of autopsy was compared with the occipito-frontal head circumference (OFC) in 251 newborns and infants. Over the range of occipito-frontal circumference studied (24-44 cm), linear correlation best described the relationship between OFC and brain weight. These data would support the reliability of the OFC as a measurement of brain growth during early infancy.
  • Article
    A case-control study was undertaken of volumetric computerized tomographic scan measures in 216 consecutive admissions for functional psychosis and 67 healthy community controls. Odds ratio analysis demonstrated significant linear trends in the association between increasing lateral and third ventricle volumes, and both RDC schizophrenia (N = 121) and schizo-affective disorder (N = 41); cases were consistently associated with larger volumes than controls. There was an association between larger third, but not lateral, ventricle size in affective psychoses (N = 54). These associations were statistically independent of intracranial volume, sex, social class and ethnicity, factors which were significantly associated with ventricular measures in the controls. There was no evidence of a threshold corresponding to the notion of normal versus enlarged ventricles. Within the schizophrenia group, there were no large or significant associations between ventricle dimensions and age at onset, duration of illness or pre-morbid social functioning. Neither obstetric complications nor a family history of schizophrenia or other psychiatric illness was associated with large ventricles in these cases.
  • Article
    Because the caudate nuclei receive inputs from cortical regions implicated in executive functioning and attentional tasks, caudate and total brain volumes were examined in boys with attention deficit hyperactivity disorder (ADHD) and normal comparison subjects. To gain developmental perspective, a wide age range was sampled for both groups. The brains of 50 male ADHD patients (aged 6-19) and 48 matched comparison subjects were scanned by magnetic resonance imaging (MRI). Volumetric measures of the head and body of the caudate nucleus were obtained from T1-weighted coronal images. Interrater reliabilities (intraclass correlations) were 0.89 or greater. The normal pattern of slight but significantly greater right caudate volume across all ages was not seen in ADHD. Mean right caudate volume was slightly but significantly smaller in the ADHD patients than in the comparison subjects, while there was no significant difference for the left. Together these facts accounted for the highly significant lack of normal asymmetry in caudate volume in the ADHD boys. Total brain volume was 5% smaller in the ADHD boys, and this was not accounted for by age, height, weight, or IQ. Smaller brain volume in ADHD did not account for the caudate volume or symmetry differences. For the normal boys, caudate volume decreased substantially (13%) and significantly with age, while in ADHD there was no age-related change. Along with previous MRI findings of low volumes in corpus callosum regions, these results support developmental abnormalities of frontal-striatal circuits in ADHD.
  • Article
    Twenty-six patients with RDC bipolar disorder were compared with a previously reported group of 48 RDC schizophrenics and 34 healthy controls, using volumetric MRI measurements of cerebral, cortical and sulcal volumes. The bipolar group appeared no different from the controls, and both of these groups had significantly larger cerebral and cortical volumes than the schizophrenics. Our previous report of a significantly reduced cortical volume in the schizophrenic group, with a corresponding increase in the volume of sulcal fluid is, therefore, not a generalized feature of psychotic illness but may be more specific to schizophrenia.
  • Article
    Full-text available
    This study was designed to evaluate the relation between intelligence and a variety of measures of brain structure. Magnetic resonance imaging scans were used to measure the volume of the intracranial cavity, cerebral hemispheres, lateral ventricles, temporal lobes, hippocampus, caudate, and cerebellum, as well as the overall volume of gray matter, white matter, and CSF, in 67 healthy, normal volunteers. Intelligence was measured with the Wechsler Adult Intelligence Scale--Revised. Full-scale IQ was found to be significantly correlated with intracranial, cerebral, temporal lobe, hippocampal, and cerebellar volume but not with caudate and lateral ventricle volume. There were also significant correlations of full-scale, verbal, and performance IQ with overall gray matter volume but not with white matter or CSF volume. Gender differences were noted in the pattern and number of correlations between the volume of the brain and its subregions and full-scale, verbal, and performance IQ. The results suggest that the size of some cerebral structures may account for a significant, but modest, proportion of the variance in human intelligence.
  • Article
    Normal brain development during childhood is a complex and dynamic process for which detailed scientific information is lacking. MRI techniques, combined with methods for advanced image analysis, offer the potential to begin to construct a quantitative map of normal paediatric brain development in vivo. In this study we utilize volumetric analysis of high resolution brain images obtained from MRI to describe cerebral development and morphology in 85 normal children and adolescents ranging in age from 5 to 17 years. The results show that total cerebral volume is 10% larger in boys compared with girls. However, both boys and girls show little change in total cerebral volume after the age of 5 years. Increased cortical grey matter is the primary contributor to larger brain volume in boys, thus supporting the hypothesis that gender associated differences in brain size are related to differences in cortical neuronal density. Prominent, age-related changes in grey matter, white matter and CSF volumes are evident during childhood and appear to reflect ongoing maturation and remodelling of the CNS. Both boys and girls show a similar pattern of cerebral asymmetry; a rightward prominence of cortical and subcortical grey matter and a leftward prominence of CSF is observed. IQ is positively correlated with total cerebral volume in children, in particular, with the volume of cortical grey matter in the prefrontal region of the brain. Subcortical grey matter also contributes to the variance in IQ, although to a lesser extent than cortical grey volume. Quantitative knowledge of the developing human brain will play an increasingly greater role in improving sensitivity and specificity in the interpretation of brain abnormalities in patients within the clinical environment, as well as in groups of children with suspected brain dysfunction in the research setting.
  • Article
    Modern stereological methods provide precise and reliable estimates of the number of neurons in specific regions of the brain. We decided to estimate the total number of neocortical neurons in the normal human brain and to analyze it with respect to the major macro- and microscopical structural components, to study the internal relationships of these components, and to quantitate the influence of important physiological variables on brain structure. The 94 brains reported represent a consecutive collection of brains from the general Danish population. The average numbers of neocortical neurons were 19 billion in female brains and 23 billion in male brains, a 16% difference. In our study, which covered the age range from 20 years to 90 years, approximately 10% of all neocortical neurons are lost over the life span in both sexes. Sex and age were the main determinants of the total number of neurons in the human neocortex, whereas body size, per se, had no influence on neuron number. Some of the data presented have been analyzed by using new mathematical designs. An equation predicting the total neocortical neuron number in any individual in which sex and age are known is provided.