Is body mass index in old age related to cognitive abilities? The Lothian Birth Cohort 1936 Study

We tested the hypothesis that the previously reported association between a higher body mass index (BMI) and poorer cognition in later adulthood is an artifact of confounding by previous cognitive ability and socioeconomic status. Participants were 1,079 adults aged about 70 years in the Lothian Birth Cohort 1936 Study, on whom there are IQ data from age 11. Cognitive outcome measures included: IQ at age 70 using the same test that was administered at age 11; composite measures of general cognitive ability (g factor), speed of information processing, and memory; and two tests of verbal ability. People classified as overweight or obese in later adulthood had significantly lower scores on tests of childhood IQ, age 70 IQ, g factor, and verbal ability. There was no significant association with processing speed or memory performance. After adjusting for childhood IQ and social class in general linear models, associations with age 70 IQ and g factor were nonsignificant or attenuated. However, throughout the models, there was a persistent (inverse) relationship between BMI and performance on the National Adult Reading Test (NART) and Wechsler Test of Adult Reading (WTAR), which remained significant after full adjustment for all sociodemographic and health covariates (for the NART, p = .025; for the WTAR, p = .011). The findings suggest that the previously reported BMI-cognition associations in later adulthood could be largely accounted for by prior ability and socioeconomic status, and by the possible influence of these factors on the adoption of health behaviors in adulthood.     

IQ stability: the relation between child and young adult intelligence test scores in low-birthweight samples

The stability of IQ from childhood to adulthood in low-birthweight subjects was measured in two independent samples with follow-up intervals of approximately 14 and 9.5 years. In both samples, intelligence was assessed with the WISC at a mean age of 9.5. Twenty-six subjects were retested with the WAIS at a mean age of 23.5, and 78 subjects with the BPP (the Danish Military Draft Board Intelligence Test) at the age of 19.1. Both samples obtained childhood and adult test scores below the expected means. For the Wechsler Verbal, Performance and Full-Scale IQs, the stability quotients were 0.86, 0.86, and 0.89 in the WAIS sample, and the retest correlations for the three IQs with the BPP score were 0.66, 0.65, and 0.74. Thus, the majority of children showed stable patterns of intellectual development from middle childhood to young adulthood.     

Are age-related changes in cognitive function driven by age-related changes in sensory processing?

Although there has been keen interest in the association among measures of sensory function and cognitive function for many years, in general, measures of sensory function have been confined to one or two senses and measures of threshold sensitivity (acuity). In this study, rigorous psychophysical measures of threshold sensitivity, temporal gap detection, temporal order identification, and temporal masking have been obtained, in hearing, vision, and touch. In addition, all subjects completed 15 subtests of the Wechsler Adult Intelligence Scale, 3rd edition (WAIS–III). Data were obtained from 245 adults (18–87 years old) for the WAIS–III and for 40 measures of threshold sensitivity and temporal processing. The focus in this report is on individual differences in performance for the entire data set. Principal-components (PC) factor analysis reduced the 40 psychophysical measures to eight correlated factors, which were reduced further to a single global sensory processing factor. Similarly, PC factor analysis of the 15 WAIS–III scores resulted in three correlated factors that were further reduced to a single global cognitive function factor. Age, global sensory processing, and global cognitive function were all moderately and significantly correlated with one another. However, paired partial correlations, controlling for the third of these three measures, revealed that the moderate correlation between age and global cognitive function went to zero when global sensory processing was controlled for; the other two partial correlations remained intact. Structural models confirmed this result. These analyses suggest that the long-standing observation of age-related changes in cognitive function may be mediated by age-related changes in global sensory processing.     

A Neuropsychological Approach to Intelligence

This paper proposes that current psychometric intelligence tests are limited in evaluating cognitive activity. From a neuropsychological perspective, they fail to measure some fundamental cognitive abilities such as executive functions, memory, and visuospatial abilities. The analysis of the Wechsler Intelligence Scale presented shows that the original rationale for selecting the specific subtests included in the WAIS was unclear. The concept of a g factor in cognition is also analyzed, with the conclusion that the g factor continues to be controversial. The value of intelligence tests in predicting school performance is also criticized. It is proposed that the psychometric concept of general intelligence should be deleted from cognitive and neurological sciences. Finally, it is proposed that, in the future, neuropsychological instruments sensitive to more specific cognitive abilities replace current psychometric intelligence tests.     

智力结构的分化假设

该文探讨了智力结构随能力、年龄等个体差异而变化的可能性。认知分化假设认为,能力水平更高的人有“更多”的智力,其智力结构中g因素的作用随IQ水平的增加而递减。年龄分化假设指出,从童年期到青年早期,g因素在认知能力中的作用随年龄的增加而减小;相反,从青年早期到成年晚期,g因素的作用递增,智力结构中其他因素的数量和重要性则递减。该领域未来的研究应当解决测量和评估工具的问题,扩大被试的能力水平和年龄范围     

The differentiation hypothesis and the Flynn effect

Many studies have shown that IQs have been increasing over the last half century. These increases have come to be known as "the Flynn effect". The "Flynn effect" represents a difference on ability-level between groups of the same age but different cohort. The ability-level differentiation hypothesis represents a difference on the relevance of cognitive factors between groups of high and low ability. Hence, it should be possible to imitate the ability-level differentiation effect by comparing groups of the same age but different cohort. The indifferentiation hypothesis represents no differences on the relevance of cognitive abilities in all age groups within the same cohort. The aim of the present study is to test the relationships between these phenomena. For this purpose we analyzed the American standardisation samples of the WISC, WISC-R and WISC-III. Results support the link between the Flynn effect and the differentiation hypothesis. Also, reported evidence replicate previous findings supporting the indifferentiation hypothesis. Implications for the assessment of the intelligence are discussed.     

Comparative relationships of the Wechsler Adult Intelligence Scale—Revised (WAIS-R) and the Wechsler Adult Intelligence Scale (WAIS) to the Wechsler Memory Scale (WMS)

This study investigated whether the Wechsler Adult Intelligence Scale — Revised (WAIS-R) and Wechsler Adult Intelligence Scale (WAIS) demonstrate similar patterns of relationship with the Wechsler Memory Scale (WMS). Sixty VA patients were administered the WAIS-R and WMS and 60 completed the WAIS and WMS. The groups were comparable in terms of demographic variables. Pearson correlations were computed between the subtest and IQ scores from the intelligence scales and the scores from the WMS for each group. Comparison of the resulting correlations for the WAIS-R group with those of the WAIS subjects demonstrated only four significant differences, indicating that the WAIS-R and WAIS variables covary in a similar manner with the WMS scores. Following factor analysis of the test data for both groups, coefficients of congruence indicated a high degree of similarity between the two factor solutions. Essentially the same relationships emerged between intelligence variables and the WMS regardless of which scale was administered.     

Correlations of measures of personality and of intelligence within and across generations

Members of over 100 families were administered the Wechsler Adult Intelligence Scale (WAIS) as well as various psychometric tests of personality. Individual cognitive and personality measures often were associated. Parent personality scale scores often were associated with offspring WAIS scores and vice versa. Stepwise multiple regressions demonstrated that knowledge of parental personality test scores substantially increased the predictability of offspring WAIS scores.     

Factor analysis of the Wechsler adult intelligence scale-revised (WAIS-R): An examination of the standardization sample

Orthogonal and oblique factor analyses were performed using the Wechsler Adult Intelligence Scale-Revised (WAIS-R) standardization sample (Wechsler, 1981). Using objective criteria, it was decided to retain two factors. Evidence for a strong general intelligence (g) factor was found from both the orthogonal and oblique rotations. Whereas the verbal IQ provided an acceptable estimate of the Verbal Comprehension factor, a purer measure was found in the form of a Verbal Comprehension Deviation Quotient containing only the Information, Vocabulary, Comprehension, and Similarities subtests. The performance IQ was found to be an inadequate measure of the Perceptual Organization factor. A Perceptual Organization Deviation Quotient, containing only the Block Design and Object Assembly subtests, was recommended as an effective alternative. Analysis of the variance components for each subtest at every age level revealed that a substantial proportion of subtests at a wide range of age levels evidence either high or intermediate levels of specific variance. These results are discussed in terms of interpreting individual subtest scores and patterns. Each of the study's major findings are compared with prior work done with the Wechsler Adult Intelligence Scale (WAIS) (Wechsler, 1955).     

Thought Disorder on the WAIS-R Relative to the Rorschach: Assessing Identity-Disordered Adolescents

Clinical researchers have noted that compared with other diagnostic groups, adults with Borderline Personality Disorder tend to demonstrate relatively more thought disorder on unstructured projective tests (e.g., Rorschach) than on structured objective tests of cognitive performance (e.g., Wechsler Adult Intelligence Scale; WAIS). Using archival data, our study found evidence that adolescents with Identity Disorder tend to exhibit this same phenomenon. The records of 62 adolescent inpatients who had been administered the WAIS or WAIS-R and the Rorschach were examined. Of the 62 cases, 25 were diagnosed with Identity Disorder, 14 with Conduct Disorder (Group Type), 15 with Oppositional Defiant Disorder, and 8 with Schizophreniform Disorder. For each participant, the WAIS or WAIS-R and the Rorschach were scored according to the Thought Disorder Index (TDI; Johnston & Holzman). Adolescents with Identity Disorder revealed a significantly larger discrepancy between TDI scores on the WAIS or WAIS-R and TDI scores on the Rorschach than did adolescents with other diagnoses. The findings suggested that the discrepancy between the degree of thought disorder on structured versus unstructured psychological tests (i.e., differential decompensation) is related to diagnosis.     

Apolipoprotein e gene variability and cognitive functions at age 79: a follow-up of the Scottish mental survey of 1932

Apolipoprotein E (APOE) genotype is a possible influence on nonpathological cognitive aging. The authors studied 462 community-dwelling, 79-year-old people born in 1921, whose childhood IQ had been assessed in the Scottish Mental Survey of 1932 (Scottish Council for Research in Education, 1933). Adjusting for sex, childhood IQ, and self-reported illnesses, the authors found that those with an APOE e4 allele had significantly lower Wechsler Logical Memory (D. Wechsler, 1987) scores than those without an e4 allele. Those people with APOE s2/e3 genotypes had significantly higher Wechsler Logical Memory scores than e3/s3, who were significantly higher than e3/e4. Neither nonverbal reasoning nor verbal fluency were affected. In this sample, APOE genotype contributed to verbal memory in old age.     

The ABCs of depression: integrating affective, biological, and cognitive models to explain the emergence of the gender difference in depression

In adulthood, twice as many women as men are depressed, a pattern that holds in most nations. In childhood, girls are no more depressed than boys, but more girls than boys are depressed by ages 13 to 15. Although many influences on this emergent gender difference in depression have been proposed, a truly integrated, developmental model is lacking. The authors propose a model that integrates affective (emotional reactivity), biological (genetic vulnerability, pubertal hormones, pubertal timing and development) and cognitive (cognitive style, objectified body consciousness, rumination) factors as vulnerabilities to depression that, in interaction with negative life events, heighten girls' rates of depression beginning in adolescence and account for the gender difference in depression.     

Rising verbal intelligence scores: implications for research and clinical practice

Evidence suggests that scores on various intelligence tests have been rising at a fast rate. To find out whether performance on the Wechsler Adult Intelligence Scale (WAIS) Vocabulary subtest has also been rising, the authors searched major psychology journals for investigations involving healthy younger and older adult participants and collected the reported WAIS Vocabulary scores. The meta-analysis shows that WAIS Vocabulary scores have been rising at the rate of 0.117/year (corresponding to 1.52 IQ points/decade) for younger adults and 0.367/year (corresponding to 4.79 IQ points/decade) for older adults.     

Dramatic Increase in Heritability of Cognitive Development From Early to Middle Childhood: An 8-Year Longitudinal Study of 8,700 Pairs of Twins

ABSTRACT— The generalist genes hypothesis implies that general cognitive ability ( g ) is an essential target for understanding how genetic polymorphisms influence the development of the human brain. Using 8,791 twin pairs from the Twins Early Development Study, we examine genetic stability and change in the etiology of g assessed by diverse measures during the critical transition from early to middle childhood. The heritability of a latent g factor in early childhood is 23%, whereas shared environment accounts for 74% of the variance. In contrast, in middle childhood, heritability of a latent g factor is 62%, and shared environment accounts for 33%. Despite increasing importance of genetic influences and declining influence of shared environment, similar genetic and shared environmental factors affect g from early to middle childhood, as indicated by a cross-age genetic correlation of .57 and a shared environmental correlation of .65. These findings set constraints on how genetic and environmental variation affects the developing brain.     

Stanford-Binet and WAIS IQ differences and their implications for adults with intellectual disability (aka mental retardation)

Stanford-Binet and Wechsler Adult Intelligence Scale (WAIS) IQs were compared for a group of 74 adults with intellectual disability (ID). In every case, WAIS Full Scale IQ was higher than the Stanford-Binet Composite IQ, with a mean difference of 16.7 points. These differences did not appear to be due to the lower minimum possible score for the Stanford-Binet. Additional comparisons with other measures suggested that the WAIS might systematically underestimate severity of intellectual impairment. Implications of these findings are discussed regarding determination of disability status, estimating prevalence of ID, assessing dementia and aging-related cognitive declines, and diagnosis of ID in forensic cases involving a possible death penalty.     

Intellectual functioning in adults with ADHD: a meta-analytic examination of full scale IQ differences between adults with and without ADHD

Although attention has been given to the intellectual functioning of children with attention-deficit/hyperactivity disorder (ADHD) relative to their non-ADHD peers, few studies have examined intellectual functioning in adults with ADHD. The purpose of the current investigation was to examine differences in intellectual ability between adults with and without ADHD via a meta-analytic review. Of the 33 studies meeting inclusion criteria, primary analyses focused on 18 studies representing 1,031 adults with ADHD and 928 non-ADHD, nonclinical comparison adults and containing Wechsler Adult Intelligence Scale (WAIS; D. Wechsler, 1955, 1981, 1994) Full Scale IQ scores or estimates. A significant effect was found such that adults with ADHD scored lower than non-ADHD adults on WAIS intelligence tests. However, this difference was small and not clinically meaningful. The presence of several moderators reflecting characteristics of the ADHD samples and study methodology suggested that only a subset of adults with ADHD (e.g., those with comorbid disorders) may experience lower general intellectual ability relative to non-ADHD comparison adults. Implications of the findings for clinical and research settings are presented as well as suggestions for improving methodology and reporting in future research.     

The structure of cognitive abilities in youths with manic symptoms: a factorial invariance study

This study compared the structure of cognitive ability (specifically, verbal/crystallized [Gc] and visual-spatial ability [Gv]), as measured in the Wechsler Intelligence Scale for Children, in youth with manic symptoms with a nationally representative group of similarly aged youth. Multigroup confirmatory factor analysis found the majority of the estimated parameters were invariant between the groups, although there was a difference in the intercepts for the Similarities subtest and difference in unique variances for the Picture Completion, Comprehension, and Picture Arrangement subtests. Thus, although there are many neurological changes associated with manic symptoms, the structure of verbal/crystallized and visual-spatial abilities appear relatively robust and invariant. As Gc and Gv are the primary domains on all the Wechsler Intelligence Scales for Children, results also indicate that clinical interpretation of the Wechsler scales may be appropriate to measure cognitive performance in youths with manic symptoms.     

Further analyses of the effects of practice,dropout, sex,socio-economic advantage,and recruitment cohort differences during the University of Manchester longitudinal study of cognitive change in old age

A sample of 4,314 volunteers who, when first recruited, were aged from 41 to 93 years were quadrennially tested from 2 to 4 occasions during the next 4 to 20 years on the Cattell Culture Fair intelligence test, 2 tests of information-processing speed, the Wechsler Adult Intelligence Scale (WAIS) vocabulary test, and 3 memory tests. After significant effects of practice, sex, demographics, socio-economic advantage, and recruitment cohort had been identified and considered, performance on all tests declined with age. These age-related declines accelerated for the Cattell and WAIS, 2 tests of information speed, and 2 of the memory tests. For all tests individuals' trajectories of age-related change diverged with increasing age but, unexpectedly, were not affected by demographic factors. Practice gains from an initial experience of the cognitive tests remained undiminished as the interval before the second experience increased from 4 to 8 + years.     

Properties of the diffuse thalamocortical system, human intelligence and differentiated vs integrated modes of learning

In complementary reports Robinson (1982a, b) describes how the transmission characteristics or time constants of thalamic and cortical neuron populations of the diffuse thalamocortical system (DTS) can be evaluated in human subjects. Equating these constants with the Pavlovian property of ‘strength’ it was predicted that they should relate to Extraversion and Neuroticism scores on the Eysenck Personality Questionnaire (EPQ). This prediction was confirmed and the results provide direct support for the theories of Pavlov and Eysenck. The present report describes additional results which confirm predictions relating the DTS constants to performance on the Wechsler Adult Intelligence Scale (WAIS) and on the Embedded Figures Test (EFT). An important finding was that a measure of deviation from intermediate and ‘balanced’ values of the DTS constants loads to the extent of -0.80 on the WAIS ‘memory’ or ‘attention/ concentration’ factor. More generally, the results provide further support for Pavlov's conception of brain-behaviour relationships and suggest that the DTS plays a fundamental role in determining a broad spectrum of human psychological differences including some associated with the concepts of intelligence and cognitive style. These IQ and cognitive style differences are explained as the immediate and longer-term consequences, respectively, of differences in the distribution of background cortical activity mediated by the DTS.     

The effects of haloperidol on thought disorder and IQ in schizophrenia

The impact of haloperidol treatment on the Wechsler Adult Intelligence Scale (WAIS) and the Thought Disorder Index was investigated in a group of 19 patients with schizophrenia tested both before and after 26 days of treatment with haloperidol. Thought disorder scores declined significantly over the course of treatment and fewer patients demonstrated severe forms of thought disorder at the end of the trial. WAIS performance improved significantly but the magnitude of change was consistent with the literature on expected practice effects. Thought disorder scores were negatively correlated with IQ at baseline, but not at Day 26. The results suggest a partial dissociation of thought disorder and other cognitive functions in schizophrenia.