Typical intellectual engagement and cognition in the ninth decade of life: The Lothian Birth Cohort 1921

Investment traits-the tendency to seek out and engage in cognitive activity-might affect intellectual growth across the life span, specifically the development from fluid to crystallized intelligence. Here we explore how childhood IQ at age 11 years, IQ at age 79, and the investment trait Typical Intellectual Engagement (TIE) at age 81 affect the mean level and change in verbal fluency scores, used as an indicator of crystallized intelligence, across the ages 79, 83, and 87 in the Lothian Birth Cohort 1921 (maximum N = 569; Deary, Whiteman, Starr, Whalley, & Fox, 2004). A first latent growth model showed significant variance in the mean level of verbal fluency and significant decline in verbal fluency from age 79 to age 87. The rate of change was invariant across study participants in the Lothian Birth Cohort 1921. A second model found that IQ at age 11 significantly predicted IQ at age 79 (β = .66; p < .001), which in turn predicted verbal fluency and TIE in the ninth decade of life with standardized path parameters of .46 and .15 (p < .001), respectively. TIE had a significant association with verbal fluency (β = .14, p = .002); together, IQ at age 11 and 79 and TIE accounted for 25.5% of the variance in verbal fluency. A final model identified the TIE subfactor of intellectual curiosity as a significant mediator of the effect of IQ on verbal fluency; the TIE subfactors abstract thinking, reading, and problem solving showed no significant associations. In summary, TIE-in particular, intellectual curiosity-significantly mediated the effects of IQ on crystallized intelligence in old age. Because there was no significant between-subjects variance in verbal fluency trajectories in the current study, neither TIE nor IQ were associated with individual differences in cognitive decline. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Vision and intelligence at age 83 in the Lothian Birth Cohort 1921

The extent to which visual function, measured as near and distant visual acuity and contrast sensitivity, is correlated with concurrently measured cognitive function and prior intellectual ability was investigated in a narrow age range group known as the Lothian Birth Cohort of 1921 (LBC1921). Participants were aged ~ 83 years at the time of testing (N = 321). A well-fitting structural equation model highlighted a significant contribution of a latent visual trait to a general fluid intelligence factor in old age, independent of the contribution from childhood intelligence. Additionally, childhood intelligence made a significant contribution to the general visual factor in old age. However, the model fitted equally well when the fluid intelligence factor is assumed to be a cause of the visual function latent trait, in which case childhood intelligence does not significantly influence vision in old age. We discuss these results with respect to four possible mechanisms by which vision and cognition can come to be correlated over the lifecourse.     

Recycling,evolution and the structure of human personality

Lower childhood cognitive ability may be a risk factor for greater cognitive decline in late life and progression to dementia. To assess variation in age-related cognitive change, it is helpful to have valid measures of cognitive ability from early life. Here, we examine the relation between childhood intelligence and cognitive change in later life in two samples, one born in 1921 and the other in 1936. All participants completed the same test of mental ability (one of the Moray House Test series) at age about 11 years, and were re-examined on Raven’s Progressive Matrices at age 77 (1921-born) or age 64 (1936-born). Where possible, the 1921 sample was re-tested at the age of about 80 years old and the 1936 sample re-tested at about 66 years. After taking into account various covariates, including sex, education and occupation, childhood intelligence was a significant predictor of cognitive change in later life. Results were in the direction that participants with lower childhood mental ability experienced relatively greater cognitive decline, whereas those of higher childhood mental ability showed improved performance. This result suggests that higher premorbid cognitive ability is protective of decline in later life.     

Reverse causation in activity-cognitive ability associations: the Lothian Birth Cohort 1936

Active lifestyles might protect cognitive abilities; however, studies rarely consider the reverse causal direction. Activity-cognition associations might reflect stable intelligence differences rather than a protective effect of activity. The Lothian Birth Cohort 1936 (n = 1091) completed cognitive tests aged 70, having taken an intelligence test aged 11. Activity (assessed by participation in 15 activities that produced a socio-intellectual activity factor, and by physical activity) was positively associated with cognition (r = .08 to .32, p ≤ .05). When age-11 IQ and adult social class were controlled, only physical activity remained significantly associated with general cognitive ability and processing speed.     

Intergenerational class mobility in Britain: A comparative look across three generations in the Lothian Birth Cohort 1936

The Lothian Birth Cohort 1936 sample is in a uniquely good position to provide relevant data on social class mobility patterns over most of the last century. These participants, with known ultimate social class attainment, took a validated mental test in the Scottish Mental Survey of 1947 and were followed up at approximately age 70. Then, besides their own age 11 mental ability data and educational and occupational attainment, they reported educational and occupational data on their parents and offspring. We constructed structural equation models of participant and offspring social class attainment and odds of social class movement, and compared results with those from the similarly recruited and assessed Lothian Birth Cohort 1921. In the 1936 cohort, relative transmission of social class from one generation to the next decreased, while relative transmission of educational attainment increased. In addition, effects of childhood IQ and educational attainment on social class decreased, apparently due to relative decrease in overall upward mobility and absolute increase in overall education level.     

The association between cognitive ability across the lifespan and health literacy in old age: The Lothian Birth Cohort 1936

Three hundred and four participants in the Lothian Birth Cohort 1936 study took a validated IQ-type test at age 11 years and a battery of cognitive tests at age 70 years. Three tests of health literacy were completed at age 72 years; the Rapid Estimate of Adult Literacy in Medicine (REALM), the Test of Functional Health Literacy in Adults (S-TOFHLA), and the Newest Vital Sign (NVS). Participants who had a lower childhood IQ exhibited poorer performance on all three tests of health literacy taken in older adulthood. Relative cognitive change from age 11 to 70 and education were also important factors influencing performance on health literacy tasks, independent of childhood cognitive ability. It is important to understand the determinants of low health literacy in order to support individuals in managing their own health.     

Personality traits in old age: measurement and rank-order stability and some mean-level change

Lothian Birth Cohorts, 1936 and 1921 were used to study the longitudinal comparability of Five-Factor Model (McCrae & John, 1992) personality traits from ages 69 to 72 years and from ages 81 to 87 years, and cross-cohort comparability between ages 69 and 81 years. Personality was measured using the 50-item International Personality Item Pool (Goldberg, 1999). Satisfactory measurement invariance was established across time and cohorts. High rank-order stability was observed in both cohorts. Almost no mean-level change was observed in the younger cohort, whereas Extraversion, Agreeableness, Conscientiousness, and Intellect declined significantly in the older cohort. The older cohort scored higher on Agreeableness and Conscientiousness. In these cohorts, individual differences in personality traits continued to be stable even in very old age, mean-level changes accelerated.     

Placing inspection time, reaction time, and perceptual speed in the broader context of cognitive ability: The VPR model in the Lothian Birth Cohort 1936

The idea that information processing speed is related to cognitive ability has a long history. Much evidence has been amassed in its support, with respect to both individual differences in general intelligence and developmental trajectories. Two so-called elementary cognitive tasks, reaction time and inspection time, have been used to compile this evidence, but most studies have used either one or the other. Relations between speed and fluid intelligence have tended to be stronger than those between speed and crystallized intelligence, but studies testing this have confounded verbal abilities with crystallized intelligence and spatial/perceptual abilities with fluid intelligence. Questions have also been raised regarding whether speed contributes directly to general intelligence or to more specific cognitive abilities to which general intelligence also contributes. We used 18 ability and speed measures in the Lothian Birth Cohort 1936, assessed at approximately age 70, to construct alternative versions of the Verbal-Perceptual-Image Rotation (Johnson & Bouchard, 2005a) model of cognitive ability to test different hypotheses regarding these issues. Though differences in the extents to which our models fit the data were relatively small, they suggested that reaction and inspection time tasks were comparable indicators of information processing speed with respect to general intelligence, that verbal and spatial abilities were similarly related to information processing speed, and that spatial, verbal, and perceptual speed abilities were more directly related to information processing speed than was general intelligence. We discuss the theoretical implications of these results.     

A pilot study of urinary peptides as biomarkers for intelligence in old age

Intelligence is an important indicator of physical, mental and social well-being. In old age, intelligence is also associated with a higher quality of life and better health. Heritability studies have shown that there are strong genetic influences, yet unknown, on intelligence, including in old age. Other approaches may be useful to investigate the biological foundations of intelligence differences. Proteomics is a proven technique in revealing biomarkers for certain illnesses. In this pilot study, forty individuals were selected as the cognitive extremes from over 750 people in the Lothian Birth Cohort 1936 (age ~ 72 years) based on their high and low intelligence scores, as measured by a general cognitive ability factor. Urine samples were used as a stable, reliable and abundant source of proteins. Using capillary electrophoresis coupled to mass spectrometry (CE-MS) technology, the proteome of the high and low intelligence groups was determined. Data were calibrated and matched against the human urinary database, to enable comparative assessment. At a nominal significance level (P < 0.05), there were several candidate proteins for association with intelligence, including a zinc finger protein (ZNF653) that has been associated with cognitive deficits, and complement C3 and collagen fragments that have been associated with Alzheimer's disease. Results are preliminary, do not survive multiple testing correction, and require validation. This pilot study shows the potential of this novel proteomics approach, and its applicability to understanding the biological foundations of intelligence differences.     

The impact of childhood intelligence on later life: following up the Scottish mental surveys of 1932 and 1947

The Scottish Mental Surveys of 1932 and 1947 collected valid IQ-type test scores for almost everyone born in 1921 and 1936 and attending school on June 1, 1932 (N=89,498) and June 4, 1947 (N=70,805). These surveys are described. This research, using the surveys' data, examined (a) the stability of intelligence differences across the life span, (b) the determinants of cognitive change from childhood to old age, and (c) the impact of childhood intelligence on survival and health in old age. Surviving participants of the Scottish Mental Surveys were tested, and the surveys' data were linked with public and health records. Novel findings on the stability of IQ scores from age 11 to age 80; sex differences in cognitive aging; the dedifferentiation hypothesis of cognitive aging; and the effect of childhood IQ on all-cause and specific mortality, morbidity, and frailty in old age are presented.     

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.     

Do personality scale items function differently in people with high and low IQ?

Intelligence differences might contribute to true differences in personality traits. It is also possible that intelligence might contribute to differences in understanding and interpreting personality items. Previous studies have not distinguished clearly between these possibilities. Before it can be accepted that scale score differences actually reflect personality differences, personality items should show measurement invariance. The authors used item response theory to test measurement invariance in the five-factor model scales of the International Personality Item Pool (IPIP) and NEO-Five-Factor Inventory (NEO-FFI) across two groups of participants from the Lothian Birth Cohort 1936 with relatively low and high cognitive abilities. Each group consisted of 320 individuals, with equal numbers of men and women. The mean IQ difference of the groups was 21 points. It was found that the IPIP and NEO-FFI items were measurement invariant across all five scales, making it possible to conclude that any differences in IPIP and NEO-FFI scores between people with low and high cognitive abilities reflected personality trait differences.     

Childhood cognitive ability,education, and personality traits predict attainment in adult occupational prestige over 17 years

This study explored a longitudinal data set of nearly 5000 adults examining the effects of childhood cognitive ability (measured at age 11), parental social class (measured at birth), and personality on current occupational prestige (all measured at age 50), taking account the effects of education and the previous occupational levels (both measured at age 33). Participants' levels of occupational attainment significantly went up from age 33 to age 50. Correlational analysis showed childhood cognitive ability, parental social class, education and occupation, and personality traits (openness, conscientiousness, extraversion, emotional stability) were all significantly associated with current occupational prestige. The strongest correlates of current occupational levels were educational qualifications, followed by childhood cognitive ability, parental social class, and personality traits. Structural equation modelling showed that for the change of occupation over 17 years, the strongest predictor was education, followed by childhood intelligence. Personality traits (extraversion, conscientiousness, and openness) had modest but significant influence in the upgrading of occupational attainment over the period of time, and parental social status predicted occupational change mediated through education and initial occupational levels. Education and childhood intelligence are more powerful predictors of current occupational prestige than personality factors or family social background. The implications for policy making and equal opportunities for education are discussed.     

Stimulation seeking and intelligence: a prospective longitudinal study

The prediction that high stimulation seeking 3-year-olds would have higher IQs by 11 years old was tested in 1,795 children on whom behavioral measures of stimulation seeking were taken at 3 years, together with cognitive ability at 11 years. High 3-year-old stimulation seekers scored 12 points higher on total IQ at age 11 compared with low stimulation seekers and also had superior scholastic and reading ability. Results replicated across independent samples and were found for all gender and ethnic groups. Effect sizes for the relationship between age 3 stimulation seeking and age 11 IQ ranged from 0.52 to 0.87. Findings appear to be the first to show a prospective link between stimulation seeking and intelligence. It is hypothesized that young stimulation seekers create for themselves an enriched environment that stimulates cognitive development.     

Season of birth and childhood intelligence: Findings from the Aberdeen Children of the 1950s cohort study

Background. In this study, 2 main hypotheses have been put forward to explain the variation in childhood intelligence or school performance by season of birth. In the first hypothesis, it is suggested that it is due to school policy concerning school entry, whereas the second suggests that a seasonally patterned exposure such as temperature, maternal nutrition, or infection during critical periods of brain development have a lasting effect on intelligence. Aims. To determine whether childhood performance on tests of different domains of intelligence is patterned by season of birth and to examine possible mechanisms for any associations. Sample. 12,150 individuals born in Aberdeen, Scotland between 1950 and 1956. Methods. Birth cohort study in which the variation in different domains of childhood intelligence measured at ages 7, 9, and 11 by season of birth were examined. Results. Reading ability at age 9 and arithmetic ability at age 11 varied by season of birth, with lowest scores among those born in autumn or early winter (September–December) and highest scores among those born in later winter or spring (February–April); p = .002 for joint sine‐cosine functions for reading ability at age 9 and p = .05 for sine‐cosine function for arithmetic ability at age 11. The child's perception and understanding of pictorial differences at age 7, verbal reasoning at 11, and English language ability at 11 did not vary by season of birth. Age at starting primary school and age relative to class peers were both associated with the different measurements of childhood intelligence and both attenuated the association between month of birth and reading ability at age 9 and arithmetic ability at age 11 towards the null. Both adjusted and unadjusted differences in reading ability at age 9 and arithmetic ability at age 11 between those born from September to December compared with other times of the year were less than 0.1 of a standard deviation of the test scores. Ambient temperature around the time of conception, during gestation, and around the time of birth did not affect intelligence. Conclusion. Any variation in mean childhood intelligence by season of birth is weak and largely explained by age at school entry and age relative to class peers.     

Relation of birth weight, maternal intelligence and mother–child interactions to cognitive and play competence of Jamaican two-year old children

The present study assessed whether birth weight, maternal child rearing behaviors, and maternal intelligence combine in an additive or in a non-linear interactive fashion to influence cognitive performance in a sample of 24-month old full-term appropriate and low birth weight Jamaican children. Child cognitive performance was measured using the Griffiths Scale and a laboratory based assessment of the amount of time the child utilized different levels of play behavior. Mothers were videotaped while playing with their children under different instructional conditions and videotapes were coded for 8 maternal interaction patterns. Maternal verbal intelligence was assessed using the PPVT. Results supported the operation of both additive co-action as well as non-linear interactive processes. Birth weight, maternal behaviors toward her child and maternal intelligence predicted child cognitive performance. In addition, low birth weight infants were either less sensitive to facilitative aspects of maternal behaviors and/or more sensitive to maternal inhibitory behaviors than were appropriate birth weight infants. Further, child rearing behaviors of more intelligent mothers were a stronger influence on their child's cognitive performance than those of less intelligent mothers, even when there were no differences in the level of behaviors of more or less intelligent mothers.     

成人认知功能的发展与老化：一项控制同辈效应的横断研究

为探索成人认知功能的发展与认知老化轨迹,基于中华成人智力量表常模样本数据,统计控制教育水平和职业构成以部分消除同辈效应,考察智商和智力指数的年龄趋势。结果晶体智力指数(CI)在25~44岁间增加0.69分后缓慢递减,高低差值3.3分;注意记忆指数(AMI)在25~44岁间共减少3.3分,45岁后各组均数以3分左右的速度递减。流体智力指数(FI)和智商的年龄差异模式与AMI类似,幅度缩减。提示中国成人晶体智力在74岁前比较稳定,没有明显老化,流体智力和注意记忆能力可能在45岁开始明显线性老化。     

Stability and change in adult intelligence: 2. Simultaneous analysis of longitudinal means and covariance structures

We analyzed data on psychometric intelligence from the Seattle Longitudinal Study, simultaneously estimating longitudinal factors, their covariance structure, and their mean levels. Data on five Thurstone Primary Mental Abilities subtests were available for 412 adults, ages 22-70 at first test, who were tested three times at 7-year intervals. A previous longitudinal factor analysis had shown high stability of individual differences (covariance stability) in general intelligence for three adult age groups. We extended that model to estimate factor means. All three age groups showed high levels of covariance stability, but differed sharply in their mean profiles. The young group showed increasing levels of general intelligence, the middle-aged group had stable levels of intelligence, and the old group showed salient, approximately linear, decline. The patterns of stability in middle-age, followed by mean decline and high covariance stability in old age, suggest a normative developmental transition from a stability pattern to a decline pattern of general intelligence, with the inflection point occurring somewhere around age 60.     

Ability Emotional Intelligence Predicts Quality of Life beyond Personality,Affectivity, and Cognitive Intelligence

The current study explored the incremental validity of the ability emotional intelligence test to predict suicidal ideation (a subjective indicator of Quality of Life) beyond the ‘Big Five’ personality dimensions, affectivity, and general cognitive ability in a sample of 184 university students (mean age 29.50 years). Hierarchical regression analyses revealed that after controlling for demographic variables, the Big Five personality traits, affectivity, and the cognitive intelligence, the block of ability emotional intelligence scores explained a statistically significant increment of variance in suicidal ideation. It is noteworthy that the predictive power of the ability emotional intelligence appeared to be mostly due to the contribution of its two branch scores–regulation of emotion and understanding of emotion. Findings are discussed with reference to emotional intelligence theory and suicidal behaviors.     

Visual Abilities in Older Adults Explain Age-Differences in Stroop and Fluid Intelligence but Not Face Recognition: Implications for the Vision-Cognition Connection

The associations among age, visual abilities and cognitive abilities were investigated using structural equation modeling. Measures of Visual Acuity, Colour Vision, Contrast Sensitivity, Stroop, Face Recognition and Fluid intelligence (Gf) were administered to a volunteer sample (n = 90) aged 60-87. Visual Acuity was associated with Gf even after controlling for chronological age. Age differences in Stroop were explained entirely by Colour Vision performance. However, neither Visual Acuity nor Colour Vision explained age-differences in Face Recognition. The results show that performance on some neuropsychological tests is influenced by visual ability and challenge the conventional identification of ageing effects on the Stroop task with deficits in frontal executive functioning. Visual abilities do not, however, contribute to age-differences in all cognitive domains suggesting that sensory and cognitive performance declines are not necessarily due to common biological ageing processes.