Adult life-span patterns in WAIS-R Block Design performance: Cross-sectional versus longitudinal age gradients and relations to demographic factors

Reliable change indices for 16 neuropsychological tests at six different time points

INTRODUCTION

Neuropsychological assessment often involves repeated testing in order to assess a cognitive change or conduct a longitudinal follow-up study of a patient. To assess whether the change between assessments is relevant or not, longitudinal reference data are needed. The aim of this study is to provide reference data to enable interpretation of score changes between assessments for 16 commonly used tests, at six different time intervals between successive assessments, using five reliable change indices.

METHODS

The study is part of the Normacog project, in which 388 healthy participants recruited in Spain (aged 18-84 years) were assessed on two occasions. A baseline assessment was carried out, and then followed up at 1 month (n=67), 3 months (n=64), 6 months (n=59), 9 months (n=60), 12 months (n=68), or 24 months (n=70). Longitudinal data were analyzed, and reliable change indices were calculated.

RESULTS

A significant improvement was observed between assessment scores for all time points, especially in memory-related variables. Reference data are provided using the following indices: discrepancy scores expressed in percentiles, standard deviation index (SDI), reliable change index (RCI), RCI+practice effect (RCI+PE), and standardized regression-based formulae.

CONCLUSIONS

This study provides data to analyze whether or not a cognitive change can be considered reliable. The results support the use of these reliable change indices to avoid biases related to successive assessments. This study will lay the foundations for the implementation of these tools in clinical practice, and will be a reference for the creation of reliable change indices.

Study on the age-period-cohort effects of cognitive abilities among older Chinese adults based on the cognitive reserve hypothesis

BACKGROUND

Cognitive abilities serves as a critical indicator of healthy aging. As China progresses into a stage of advanced population aging, there has been a significant increase in the number of elderly individuals experiencing age-related cognitive decline. Despite this demographic shift, there is a paucity of longitudinal research examining cognitive abilities among older Chinese adults over extended time periods. This study aims to investigate changes in cognitive abilities and explore group differences among older Chinese adults aged 65 to 110 years, employing a multidimensional temporal approach that encompasses age, period, and birth cohort effects.

METHODS

This study utilizes data from eight waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), spanning from 1998 to 2018. The dataset comprises 94,116 observations from 36,157 unique participants. Cognitive abilities are assessed using Mini-Mental State Examination (MMSE) scores as a proxy measure. To address the issue of perfect collinearity in the temporal dimension, the study employs the Hierarchical Age-Period-Cohort Cross-Classified Random Effects Model (HAPC-CCREM). This model allows for the examination of age effects, period effects, and cohort effects on cognitive abilities among older Chinese adults. In the model specification, age is treated as a fixed effect, while period and birth cohort are incorporated as random effects. Drawing upon the cognitive reserve hypothesis, the study investigates significant factors influencing cognitive abilities in this population.

RESULTS

At the fixed-effect level, demographic factors, health behaviors, self-rated health, subjective well-being, and childhood adversity significantly influence cognitive abilities among older Chinese adults. The age effects are significant, with cognitive abilities exhibiting an inverted U-shaped curve across the lifespan. At the random-effect level, period effects are significant, revealing a gradual annual increase in overall cognitive levels among older Chinese adults since 2008. Cohort effects are also significant, demonstrating an increasing trend in overall cognitive levels for the earlier-born cohorts in the first six groups. Conversely, later-born cohorts in the latter five groups show a declining trend in overall cognitive levels. Notably, period effects significantly enhance cohort effects.

CONCLUSIONS

The cognitive reserve hypothesis supports the significance of the majority of identified influencing factors. Cognitive abilities demonstrate an accelerating decline with increasing age, following an evolutionary trajectory consistent with physiological principles among older Chinese adults. Since 2008, cognitive abilities have shown a monotonic increasing trend annually, further validating the Flynn effect in this population. The cognitive abilities of the six earlier-born cohorts exhibit an increasing trend, supporting the compression of morbidity hypothesis. Conversely, the cognitive abilities of the five later-born cohorts show a declining trend, supporting the expansion of morbidity hypothesis. These findings collectively contribute to our understanding of cognitive aging patterns and their underlying mechanisms among older Chinese adults.

Revealing Cultural Dynamics in WAIS-IV Performance: a Comparative Analysis of Age Cohorts in Taiwanese and U.S. Populations

OBJECTIVE

This study examined the relationship between culture and cognitive abilities by comparing WAIS-IV subtests, index scores, and Full-Scale Intelligence Quotient (FSIQ) scores across various age groups in the Taiwanese and U.S. populations.

METHOD

The Taiwanese and U.S. versions of WAIS-IV are comprehensively compared, examining subtest items, psychometrics, and sample characteristics. Scaled scores are compared by extracting raw scores with a scaled score of 10 from each subtest scale in the Taiwanese version and applying U.S. age norms to acquire U.S. scaled scores.

RESULTS

Despite the mean FSIQ score closely aligning with the U.S. sample, notable discrepancies are evident in the Taiwanese Verbal Comprehension Index (VCI) score, potentially influenced by cultural fairness of the tests. Significant variations are observed among age cohorts in the Taiwanese sample, with younger individuals excelling in Processing Speed Index, Working Memory Index, Perceptual Reasoning Index, and FSIQ, while maintaining comparable VCI scores to their U.S. counterparts. Conversely, older cohorts demonstrate lower performance across various domains, except for visuospatial reasoning and organizational skills, compared to their U.S. counterparts. These subtest variations robustly correlate with educational disparities between the Taiwanese and U.S. samples.

CONCLUSIONS

Despite the similarity in factor structures between the Taiwanese and U.S. versions of WAIS-IV, this study reveals cultural bias in both verbal and non-verbal subtests. The study highlights the intricate interplay among cognitive processing styles, cultural influences, and educational factors contributing to performance disparities.

Adaptive measurement of cognitive function based on multidimensional item response theory

INTRODUCTION

Up to 20% of older adults in the United States have mild cognitive impairment (MCI), and about one-third of people with MCI are predicted to transition to Alzheimer's disease (AD) within 5 years. Standard cognitive assessments are long and require a trained technician to administer. We developed the first computerized adaptive test (CAT) based on multidimensional item response theory (MIRT) to more precisely, rapidly, and repeatedly assesses cognitive abilities across the adult lifespan. We present results for a prototype CAT (pCAT-COG) for assessment of global cognitive function.

METHODS

We sampled items across five cognitive domains central to neuropsychological testing (episodic memory [EM], semantic memory/language [SM], working memory [WM], executive function/flexible thinking, and processing speed [PS]). The item bank consists of 54 items, with 9 items of varying difficulty drawn from six different cognitive tasks. Each of the 54 items has 3 response trials, yielding an ordinal score (0-3 trials correct). We also include three long-term memory items not designed for adaptive administration, for a total bank of 57 items. Calibration data were collected in-person and online, calibrated using a bifactor MIRT model, and pCAT-COG scores validated against a technician-administered neuropsychological battery.

RESULTS

The bifactor MIRT model improved fit over a unidimensional IRT model (p < 0.0001). The global pCAT-COG scores were inversely correlated with age (r = -0.44, p < 0.0001). Simulated adaptive administration of 11 items maintained a correlation of r = 0.94 with the total item bank scores. Significant differences between mild and no cognitive impairment (NCI) were found (effect size of 1.08 SD units). The pCAT-COG correlated with clinician-based global measure (r = 0.64).

DISCUSSION

MIRT-based CAT is feasible and valid for the assessment of global cognitive impairment, laying the foundation for the development of a full CAT-COG that will draw from a much larger item bank with both global and domain specific measures of cognitive impairment.

Highlights

As Americans age, numbers at risk for developing cognitive impairment are increasing.Aging-related declines in cognition begins decades prior to the onset of obvious cognitive impairment.Traditional assessment is burdensome and requires trained clinicians.We developed an adaptive testing framework using multidimensional item response theory.It is comparable to lengthier in-person assessments that require trained psychometrists.

Executive functioning in early and middle age adult patients operated for epidural hematoma: A comparative study

Epidural Hematoma (EDH) is a common condition of traumatic brain injury. It has a good prognosis if prompt surgical intervention is conducted. There is a dearth of studies on neuropsychological assessment of executive functioning exclusively in post-operative EDH patients. Moreover, age as a variable in determining executive functions in patients post-head injury, has been studied mostly in the older adults. This cross-sectional case-control study assessed Executive Functions (EF) in 62 post-surgery patients with EDH and compared 57 healthy controls (HC) using standardized assessment tools of sustained attention, speed, working memory, fluency, set-shifting, perseveration, planning, and response inhibition. Further, executive functions in two phases of adulthood, viz. Early Adulthood (20-39 years) and Middle Adulthood (40-60 years) were compared in the EDH group (E-EDH and M-EDH) and HC (E-HC and M-HC). A two-way Analysis of Variance (ANOVA) and correlational analysis was conducted. Results showed a trend where the M-EDH group performed significantly poorer on executive function tests (viz a viz., time taken, errors, and correct responses), followed by E-EDH, M-HC, and E-HC. The main effect of age was found significant on Digit Symbol, Color Trail 1, N-Back 2, Animal Naming, and Stroop Effect (p < 0.01 level) while N-Back 1, WCST-PE, and Tower of London (p < 0.05 level). The findings have significant clinical and therapeutic implications. In addition, it gives guidance regarding planning specific neuropsychological tests and rehabilitation targeting specific areas of executive functions decline due to age in EDH post-surgery patients.

Looking Ahead: Advancing Measurement and Analysis of the Block Design Test Using Technology and Artificial Intelligence

The block design test (BDT) has been used for over a century in research and clinical contexts as a measure of spatial cognition, both as a singular ability and as part of more comprehensive intelligence assessment. Traditionally, the BDT has been scored using methods that do not reflect the full potential of individual differences that could be measured by the test. Recent advancements in technology, including eye-tracking, embedded sensor systems, and artificial intelligence, have provided new opportunities to measure and analyze data from the BDT. In this methodological review, we outline the information that BDT can assess, review several recent advancements in measurement and analytic methods, discuss potential future uses of these methods, and advocate for further research using these methods.

Association between physical activity, body composition, and cognitive performance among female office workers

Regular physical activity can potentially prevent cognitive decline. While most studies focused on the general decline of the elderly and child and adolescent population, aging is a gradual process and cognitive decline can commence in middle age. Other than the middle-aged working population, gender-specific nuances are another overlooked area regarding the relationship between physical activity and cognitive performance. Therefore, this study examines the associations and benefits of maintaining regular physical activity habits with cognitive function and body composition in middle-aged female office workers. The results show that middle-aged females exhibited age-related declines in working memory, while no significant age-related changes are observed in reaction time and executive function. However, the regular exercise group demonstrates the ability to maintain their cognitive performance across age, unlike the sedentary group, who experiences declines in reaction time and executive function with age. Our findings highlight the significant impact of age on specific cognitive functions in middle-aged females and the positive influence of regular exercise on cognitive performance. Furthermore, this study demonstrates the potential of "the Brain Gym" App for efficient cognitive function assessment. The findings underscore the importance of regular exercise for cognitive well-being in middle-aged females and provide valuable insights into the relationship between body composition and cognitive function.

The Impact of School Closures during COVID-19 Lockdown on Visual-Motor Integration and Block Design Performance: A Comparison of Two Cohorts of Preschool Children

The COVID-19 outbreak has led to the closure of educational institutions, which may prevent children from attaining skills essential for learning, such as visual-motor integration (VMI) and visuospatial constructional ability (often reflected with the Block Design Test, BDT). This study compares VMI and BDT performance between a pre-pandemic cohort (children who attended preschool in late 2019) and a post-pandemic cohort (those physically attending preschool for the first time at the end of 2021). Participants were children attending government preschools with similar syllabi catered for low-income families. The pre-pandemic cohort was part of an earlier study (n = 202 for VMI and n = 220 for BDT) before lockdowns commenced in March 2020. The post-pandemic cohort comprised 197 children who completed the Beery-VMI and 93 children who completed the BDT. Compared to the pre-pandemic cohort, the post-pandemic cohort had significantly lower mean Beery-VMI scores (t(397) = 3.054, p = 0.002) and was 3.162-times more likely to have a below average Beery-VMI score (OR = 3.162 (95% CI 1.349, 7.411)). The post-pandemic cohort also had significantly lower BDT scores than the pre-pandemic cohort (t(311) = -5.866, p < 0.001). In conclusion, children with disrupted conventional preschool education due to the COVID-19 lockdowns were more likely to have below-average VMI and lower BDT scores.

A massive dataset of the NeuroCognitive Performance Test, a web-based cognitive assessment

We present a dataset of approximately 5.5 million subtest scores from over 750,000 adults who completed the NeuroCognitive Performance Test (NCPT; Lumos Labs, Inc.), a validated, self-administered cognitive test accessed via web browser. The dataset includes assessment scores from eight test batteries consisting of 5-11 subtests that collectively span several cognitive domains including working memory, visual attention, and abstract reasoning. In addition to the raw scores and normative data from each subtest, the dataset includes basic demographic information from each participant (age, gender, and educational background). The scale and diversity of the dataset provides an unprecedented opportunity for researchers to investigate population-level variability in cognitive abilities and their relation to demographic factors. To facilitate reuse of this dataset by other researchers, we provide a Python module that supports several common preprocessing steps.

Practice Effects in Mild Cognitive Impairment Increase Reversion Rates and Delay Detection of New Impairments

Objective

Cognitive practice effects (PEs) can delay detection of progression from cognitively unimpaired to mild cognitive impairment (MCI). They also reduce diagnostic accuracy as suggested by biomarker positivity data. Even among those who decline, PEs can mask steeper declines by inflating cognitive scores. Within MCI samples, PEs may increase reversion rates and thus impede detection of further impairment. Within an MCI sample at baseline, we evaluated how PEs impact prevalence, reversion rates, and dementia progression after 1 year.

Methods

We examined 329 baseline Alzheimer's Disease Neuroimaging Initiative MCI participants (mean age = 73.1; SD = 7.4). We identified test-naïve participants who were demographically matched to returnees at their 1-year follow-up. Since the only major difference between groups was that one completed testing once and the other twice, comparison of scores in each group yielded PEs. PEs were subtracted from each test to yield PE-adjusted scores. Biomarkers included cerebrospinal fluid phosphorylated tau and amyloid beta. Cox proportional models predicted time until first dementia diagnosis using PE-unadjusted and PE-adjusted diagnoses.

Results

Accounting for PEs increased MCI prevalence at follow-up by 9.2% (272 vs. 249 MCI), and reduced reversion to normal by 28.8% (57 vs. 80 reverters). PEs also increased stability of single-domain MCI by 12.0% (164 vs. 147). Compared to PE-unadjusted diagnoses, use of PE-adjusted follow-up diagnoses led to a twofold increase in hazard ratios for incident dementia. We classified individuals as false reverters if they reverted to cognitively unimpaired status based on PE-unadjusted scores, but remained classified as MCI cases after accounting for PEs. When amyloid and tau positivity were examined together, 72.2% of these false reverters were positive for at least one biomarker.

Interpretation

Even when PEs are small, they can meaningfully change whether some individuals with MCI retain the diagnosis at a 1-year follow-up. Accounting for PEs resulted in increased MCI prevalence and altered stability/reversion rates. This improved diagnostic accuracy also increased the dementia-predicting ability of MCI diagnoses.

Cognitive practice effects delay diagnosis of MCI: Implications for clinical trials

INTRODUCTION

Practice effects (PEs) on cognitive tests obscure decline, thereby delaying detection of mild cognitive impairment (MCI). Importantly, PEs may be present even when there are performance declines, if scores would have been even lower without prior test exposure. We assessed how accounting for PEs using a replacement-participants method impacts incident MCI diagnosis.

METHODS

Of 889 baseline cognitively normal (CN) Alzheimer's Disease Neuroimaging Initiative (ADNI) participants, 722 returned 1 year later (mean age = 74.9 ± 6.8 at baseline). The scores of test-naïve demographically matched "replacement" participants who took tests for the first time were compared to returnee scores at follow-up. PEs-calculated as the difference between returnee follow-up scores and replacement participants scores-were subtracted from follow-up scores of returnees. PE-adjusted cognitive scores were then used to determine if individuals were below the impairment threshold for MCI. Cerebrospinal fluid amyloid beta, phosphorylated tau, and total tau were used for criterion validation. In addition, based on screening and recruitment numbers from a clinical trial of amyloid-positive individuals, we estimated the effect of earlier detection of MCI by accounting for cognitive PEs on a hypothetical clinical trial in which the key outcome was progression to MCI.

RESULTS

In the ADNI sample, PE-adjusted scores increased MCI incidence by 19% (P < .001), increased proportion of amyloid-positive MCI cases (+12%), and reduced proportion of amyloid-positive CNs (-5%; P's < .04). Additional calculations showed that the earlier detection and increased MCI incidence would also substantially reduce necessary sample size and study duration for a clinical trial of progression to MCI. Cost savings were estimated at ≈$5.41 million.

DISCUSSION

Detecting MCI as early as possible is of obvious importance. Accounting for cognitive PEs with the replacement-participants method leads to earlier detection of MCI, improved diagnostic accuracy, and can lead to multi-million-dollar cost reductions for clinical trials.

Cognitive performance in idiopathic intracranial hypertension and relevance of intracranial pressure

Cognitive impairments have been reported in idiopathic intracranial hypertension; however, evidence supporting these deficits is scarce and contributing factors have not been defined. Using a case-control prospective study, we identified multiple domains of deficiency in a cohort of 66 female adult idiopathic intracranial hypertension patients. We identified significantly impaired attention networks (executive function) and sustained attention compared to a body mass index and age matched control group of 25 healthy female participants. We aimed to investigate how cognitive function changed over time and demonstrated that deficits were not permanent. Participants exhibited improvement in several domains including executive function, sustained attention and verbal short-term memory over 12-month follow-up. Improved cognition over time was associated with reduction in intracranial pressure but not body weight. We then evaluated cognition before and after a lumbar puncture with acute reduction in intracranial pressure and noted significant improvement in sustained attention to response task performance. The impact of comorbidities (headache, depression, adiposity and obstructive sleep apnoea) was also explored. We observed that body mass index and the obesity associated cytokine interleukin-6 (serum and cerebrospinal fluid) were not associated with cognitive performance. Headache severity during cognitive testing, co-morbid depression and markers of obstructive sleep apnoea were adversely associated with cognitive performance. Dysregulation of the cortisol generating enzyme 11β hydroxysteroid dehydrogenase type 1 has been observed in idiopathic intracranial hypertension. Elevated cortisol has been associated with impaired cognition. Here, we utilized liquid chromatography-tandem mass spectrometry for multi-steroid profiling in serum and cerebrospinal fluid in idiopathic intracranial hypertension patients. We noted that reduction in the serum cortisol:cortisone ratio in those undergoing bariatric surgery at 12 months was associated with improving verbal working memory. The clinical relevance of cognitive deficits was noted in their significant association with impaired reliability to perform visual field tests, the cornerstone of monitoring vision in idiopathic intracranial hypertension. Our findings propose that cognitive impairment should be accepted as a clinical manifestation of idiopathic intracranial hypertension and impairs the ability to perform visual field testing reliably. Importantly, cognitive deficits can improve over time and with reduction of intracranial pressure. Treating comorbid depression, obstructive sleep apnoea and headache could improve cognitive performance in idiopathic intracranial hypertension.

Sex-specific effects of polygenic risk for schizophrenia on lifespan cognitive functioning in healthy individuals

Polygenic risk for schizophrenia has been associated with lower cognitive ability and age-related cognitive change in healthy individuals. Despite well-established neuropsychological sex differences in schizophrenia patients, genetic studies on sex differences in schizophrenia in relation to cognitive phenotypes are scarce. Here, we investigated whether the effect of a polygenic risk score (PRS) for schizophrenia on childhood, midlife, and late-life cognitive function in healthy individuals is modified by sex, and if PRS is linked to accelerated cognitive decline. Using a longitudinal data set from healthy individuals aged 25-100 years (N = 1459) spanning a 25-year period, we found that PRS was associated with lower cognitive ability (episodic memory, semantic memory, visuospatial ability), but not with accelerated cognitive decline. A significant interaction effect between sex and PRS was seen on cognitive task performance, and sex-stratified analyses showed that the effect of PRS was male-specific. In a sub-sample, we observed a male-specific effect of the PRS on school performance at age 12 (N = 496). Our findings of sex-specific effects of schizophrenia genetics on cognitive functioning across the lifespan indicate that the effects of underlying disease genetics on cognitive functioning is dependent on biological processes that differ between the sexes.

Normative Study of the Block Design Test for Adults Aged 55 Years and Older in Korean Aging Population

OBJECTIVE

The Block Design Test (BDT) is known to be an effective measure in diagnosing age-related cognitive decline of visuospatial function. The goal of this study is to investigate the effects of age, education years, and gender on the performance of the BDT and to provide normative data in Korean community-dwelling participants who are 55 to 90 years old.

METHODS

The participants were 432 non-demented adults aging from 55 to 90 years old. The BDT was administered to participants according to its manual. Multiple linear regressions and analyses of variance were conducted, including age, gender, and educations were used as covariates.

RESULTS

Age, educational years, and gender were found to be significantly associated with performance on the BDT. As age increased, BDT performance decreased. Educational years were associated with BDT performance. Men showed higher performance (29.9±10.3) compare to women (26.1±8.7). The BDT is influenced by age, educational years, and gender.

CONCLUSION

Unlike the previous study, the current study shows that gender has a significant influence in visuospatial ability in the old population. Present normative data will be useful for clinicians in evaluating aging participants with cognitive impairment.

Functional Neural Correlates of the WAIS-IV Block Design Test in Older Adult with Mild Cognitive Impairment and Alzheimer's Disease

The Wechsler Adult intelligence scale-Revised (WAIS-R) Block design test (BDT) is a neuropsychological test widely used to assess cognitive declines in aging population. Previous studies suggest parietal lobe is the key region to influence the performance on the BDT; yet, it has not been clearly identified. The aim of the current study, therefore, is to identify the functional neural correlates of the BDT in older adults with mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia patients. The current study includes 213 cognitively impaired mid to old-aged community dwelling Korean. All participants underwent comprehensive clinical and neuropsychological assessments and 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) scans. Performance on the BDT was assessed using the WAIS-IV Korean version. Voxel-wise analyses were used to investigate the correlation between regional cerebral glucose metabolism and BDT performance. The same analyses were conducted on the subgroups categorized by clinical severity based on the Clinical Dementia Rating (CDR). Significant positive correlations between performance on the BDT and regional cerebral glucose metabolism were found bilaterally in the inferior parietal lobules, right thalamus and right middle frontal gyrus. Our results suggest that performance on the BDT in MCI and AD patients functionally relies on the brain regions known to be associated with motor and executive functions in addition to visuospatial function.

Biological and environmental predictors of heterogeneity in neurocognitive ageing: Evidence from Betula and other longitudinal studies

Individual differences in cognitive performance increase with advancing age, reflecting marked cognitive changes in some individuals along with little or no change in others. Genetic and lifestyle factors are assumed to influence cognitive performance in ageing by affecting the magnitude and extent of age-related brain changes (i.e., brain maintenance or atrophy), as well as the ability to recruit compensatory processes. The purpose of this review is to present findings from the Betula study and other longitudinal studies, with a focus on clarifying the role of key biological and environmental factors assumed to underlie individual differences in brain and cognitive ageing. We discuss the vital importance of sampling, analytic methods, consideration of non-ignorable dropout, and related issues for valid conclusions on factors that influence healthy neurocognitive ageing.

Cognitive Practice Effects Delay Diagnosis; Implications for Clinical Trials

OBJECTIVE

Practice effects on cognitive tests obscure decline, thereby delaying detection of mild cognitive impairment (MCI). This reduces opportunities for slowing Alzheimer's disease progression and can hinder clinical trials. Using a novel method, we assessed the ability of practice-effect-adjusted diagnoses to detect MCI earlier, and tested the validity of these diagnoses based on AD biomarkers.

METHODS

Of 889 Alzheimer's Disease Neuroimaging Initiative participants who were cognitively normal (CN) at baseline, 722 returned at 1-year-follow-up (mean age=74.9±6.8). Practice effects were calculated by comparing returnee scores at follow-up to demographically-matched individuals who had only taken the tests once, with an additional adjustment for attrition effects. Practice effects for each test were subtracted from follow-up scores. The lower scores put additional individuals below the impairment threshold for MCI. CSF amyloid-beta, phosphorylated tau, and total tau were measured at baseline and used for criterion validation.

RESULTS

Practice-effect-adjusted scores increased MCI incidence by 26% (p<.001). Adjustment increased proportions of amyloid-positive MCI cases (+20%) and reduced proportions of amyloid-positive CNs (-6%) (ps<.007). With the increased MCI base rate, adjustment for practice effects would reduce the sample size needed for detecting significant drug treatment effects by an average of 21%, which we demonstrate would result in multi-million-dollar savings in a clinical trial.

INTERPRETATION

Adjusting for practice effects on cognitive testing leads to earlier detection of MCI. When MCI is an outcome, this reduces recruitment needed for clinical trials, study duration, staff and participant burden, and can dramatically lower costs. Importantly, biomarker evidence also indicates improved diagnostic accuracy.

Education and Cognitive Functioning Across the Life Span

Cognitive abilities are important predictors of educational and occupational performance, socioeconomic attainment, health, and longevity. Declines in cognitive abilities are linked to impairments in older adults' everyday functions, but people differ from one another in their rates of cognitive decline over the course of adulthood and old age. Hence, identifying factors that protect against compromised late-life cognition is of great societal interest. The number of years of formal education completed by individuals is positively correlated with their cognitive function throughout adulthood and predicts lower risk of dementia late in life. These observations have led to the propositions that prolonging education might (a) affect cognitive ability and (b) attenuate aging-associated declines in cognition. We evaluate these propositions by reviewing the literature on educational attainment and cognitive aging, including recent analyses of data harmonized across multiple longitudinal cohort studies and related meta-analyses. In line with the first proposition, the evidence indicates that educational attainment has positive effects on cognitive function. We also find evidence that cognitive abilities are associated with selection into longer durations of education and that there are common factors (e.g., parental socioeconomic resources) that affect both educational attainment and cognitive development. There is likely reciprocal interplay among these factors, and among cognitive abilities, during development. Education-cognitive ability associations are apparent across the entire adult life span and across the full range of education levels, including (to some degree) tertiary education. However, contrary to the second proposition, we find that associations between education and aging-associated cognitive declines are negligible and that a threshold model of dementia can account for the association between educational attainment and late-life dementia risk. We conclude that educational attainment exerts its influences on late-life cognitive function primarily by contributing to individual differences in cognitive skills that emerge in early adulthood but persist into older age. We also note that the widespread absence of educational influences on rates of cognitive decline puts constraints on theoretical notions of cognitive aging, such as the concepts of cognitive reserve and brain maintenance. Improving the conditions that shape development during the first decades of life carries great potential for improving cognitive ability in early adulthood and for reducing public-health burdens related to cognitive aging and dementia.

Effects of polygenic risk for Alzheimer's disease on rate of cognitive decline in normal aging

Most people's cognitive abilities decline with age, with significant and partly genetically driven, individual differences in rate of change. Although APOE ɛ4 and genetic scores for late-onset Alzheimer's disease (LOAD) have been related to cognitive decline during preclinical stages of dementia, there is limited knowledge concerning genetic factors implied in normal cognitive aging. In the present study, we examined three potential genetic predictors of age-related cognitive decline as follows: (1) the APOE ɛ4 allele, (2) a polygenic score for general cognitive ability (PGS-cog), and (3) a polygenic risk score for late-onset AD (PRS-LOAD). We examined up to six time points of cognitive measurements in the longitudinal population-based Betula study, covering a 25-year follow-up period. Only participants that remained alive and non-demented until the most recent dementia screening (1-3 years after the last test occasion) were included (n = 1087). Individual differences in rate of cognitive change (composite score) were predicted by the PRS-LOAD and APOE ɛ4, but not by PGS-cog. To control for the possibility that the results reflected a preclinical state of Alzheimer's disease in some participants, we re-ran the analyses excluding cognitive data from the last test occasion to model cognitive change up-until a minimum of 6 years before potential onset of clinical Alzheimers. Strikingly, the association of PRS-LOAD, but not APOE ɛ4, with cognitive change remained. The results indicate that PRS-LOAD predicts individual difference in rate of cognitive decline in normal aging, but it remains to be determined to what extent this reflects preclinical Alzheimer's disease brain pathophysiology and subsequent risk to develop the disease.

Greater lifestyle engagement is associated with better age-adjusted cognitive abilities

Previous evidence suggests that modifiable lifestyle factors, such as engagement in leisure activities, might slow the age-related decline of cognitive functions. Less is known, however, about which aspects of lifestyle might be particularly beneficial to healthy cognitive ageing, and whether they are associated with distinct cognitive domains (e.g. fluid and crystallized abilities) differentially. We investigated these questions in the cross-sectional Cambridge Centre for Ageing and Neuroscience (Cam-CAN) data (N = 708, age 18-88), using data-driven exploratory structural equation modelling, confirmatory factor analyses, and age-residualized measures of cognitive differences across the lifespan. Specifically, we assessed the relative associations of the following five lifestyle factors on age-related differences of fluid and crystallized age-adjusted abilities: education/SES, physical health, mental health, social engagement, and intellectual engagement. We found that higher education, better physical and mental health, more social engagement and a greater degree of intellectual engagement were each individually correlated with better fluid and crystallized cognitive age-adjusted abilities. A joint path model of all lifestyle factors on crystallized and fluid abilities, which allowed a simultaneous assessment of the lifestyle domains, showed that physical health, social and intellectual engagement and education/SES explained unique, complementary variance, but mental health did not make significant contributions above and beyond the other four lifestyle factors and age. The total variance explained for fluid abilities was 14% and 16% for crystallized abilities. Our results are compatible with the hypothesis that intellectually and physically challenging as well as socially engaging activities are associated with better crystallized and fluid performance across the lifespan.

Demographically-adjusted norms for the WAIS-R Block Design and Arithmetic subtests: Results from the Neuropsychological Norms for the US-Mexico Border Region in Spanish (NP-NUMBRS) project

OBJECTIVE

Wechsler Adult Intelligence Scale (WAIS) Block Design and Arithmetic subtests are frequently used as measures of visuospatial construction and verbal working memory, respectively. As part of a larger test adaptation and norming effort for this population, we generated and investigated demographically-adjusted interpretive norms for WAIS-R Block Design and Arithmetic in Spanish-speaking adults living in the US-Mexico border region.

METHOD

Participants included 183 community-dwelling adults ages 20-55 (education range: 0-20 years; 58% women) from the NeuroPsychological-Norms for the US-Mexico Border Region in Spanish (NP-NUMBRS) Project. They completed the WAIS-R Block Design and Arithmetic subtests in Spanish. Demographically-adjusted T-scores were calculated for these subtests using fractional polynomial equations adjusting for linear and non-linear effects of age, education (continuous), and sex. We compared our rates of impairment (i.e. T < 40) against rates calculated using published English-speaking WAIS-R standardization sample norms adjusted for age, education, and sex.

RESULTS

Education was positively associated with performance on Block Design and Arithmetic subtests, and men outperformed women on both subtests. The present Spanish-speaker norms for these subtests yielded expected rates of "impairment" (i.e. 15-16% impaired, a 1 SD cutoff), while existing norms for English-speakers underestimated impairment (i.e. 5-6% impaired) when applied to our Spanish-speaking sample.

CONCLUSIONS

Regional normative data will improve interpretation of test performance on Block Design and Arithmetic subtests for Spanish-speakers living in the US-Mexico border region and may aid in bolstering the overall analysis of neuropsychological profile patterns in this population. Cross-validation with Spanish-speakers in other regions and/or with other national origins is needed.

Cognitive Aging and Dementia: A Life Span Perspective

This article summarizes empirical findings and theoretical concepts in cognitive aging and late-life dementia research. Major emphases are placed on (1) person-to-person heterogeneity in trajectories of cognitive change over time, (2) how trajectories of child cognitive development determine peak levels of adult cognitive function from which aging-related cognitive declines occur, and (3) how lifelong trajectories of cognitive function relate to the timing of severe cognitive impairments characteristic of dementia. I consider conceptual issues surrounding categorical vs. dimensional models of late-life dementia, and how current diagnostic approaches affect inferences in the empirical study of disease progression. The incomplete current understanding of the biological foundations of aging-related cognitive declines and the continuous nature of many biomarkers commonly used in dementia diagnosis and classification together pose both opportunities and challenges in the current research landscape. Research moving forward will benefit from accurately measuring and analyzing continuous variation in longitudinal trajectories of cognitive function.

Aging-related changes in fluid intelligence, muscle and adipose mass, and sex-specific immunologic mediation: A longitudinal UK Biobank study

BACKGROUND

Obesity in midlife and early late-life is associated with worse normal cognitive aging. Dual-energy X-ray absorptiometry (DEXA) suggests that visceral adipose mass (VAM) plays a predominant role, whereas non-visceral adipose mass (NVAM) and lean muscle mass (LMM) have shown conflicting relationships. It is unknown how longitudinal, cognitive changes in age-sensitive domains like fluid intelligence (FI) correspond to VAM, NVAM, and LMM in women and men. Furthermore, changes over time in blood leukocyte sub-populations may partially or fully account for sex-specific associations.

METHODS

Data on 4431 late middle-aged, cognitively unimpaired adults (mean = 64.5 y) was obtained from the UK Biobank prospective cohort across 22 centers. FI scores, blood leukocyte counts, and covariates (age, social class, education) were measured at three 2-year intervals over 6 years. DEXA collection overlapped with these intervals. Sex-stratified growth curves, structural equations, and Preacher-Hayes mediation were used to estimate direct and indirect effects. β-weights were standardized.

RESULTS

More LMM predicted gains in FI scores among women (β = 0.130, p < .001) and men (β = 0.089, p < .001). Conversely, more VAM and NVAM independently predicted FI decline equally among sexes (e.g., NVAM: women: β = -0.082, p < .001; men: β = -0.076, p < .001). Among women, FI associations were fully mediated by higher eosinophil counts via VAM (λ = 30.8%, p = .028) and lower lymphocyte counts via LMM (λ = 69.2%, p = .021). Among men, FI associations were partially mediated by lower basophils counts via LMM (λ = 4.5%, p = .042) and higher counts via VAM (λ = 50%, p = .037).

CONCLUSION

The proportion of LMM and VAM equally influenced male FI changes over 6 years, whereas higher LMM among women appeared to more strongly influence. FI changes. Leukocyte counts strongly mediated VAM- and LMM-related FI changes in a sex-specific manner, but not for NVAM. For clinical translation, exercise studies in older adults may benefit from assessing sex-specific values of DEXA-based tissue mass, FI, and leukocyte sub-populations to gauge potential cognitive benefits of less VAM and more LMM.

Altered Resting-State Functional Connectivity in Wernicke's Encephalopathy With Vestibular Impairment

Objectives: To reveal the neural basis of Wernicke's encephalopathy (WE) with impaired vestibulo-ocular reflex (VOR), we evaluated resting-state functional connectivity (rs-fc) in the vestibular processing brain regions. Methods: Rs-fc between the vestibular regions and the rest of the brain were compared with neurotological features including the head-impulse tests (vHIT) and caloric responses in patients with WE (n = 5, mean age 53.4 ± 10 years) and healthy controls (n = 20, mean age 55.0 ± 9.2 years). Rs-fc analyses employed a region of interest (ROI)-based approach using regions selected a priori that participate in vestibular processing including the cerebellar vermis, insula, parietal operculum, and calcarine cortex. Results: The main neurologic findings for patients with WE were mental changes; gait ataxia; spontaneous and gaze-evoked nystagmus (GEN); and bilaterally positive HIT for the horizontal canals. Video HIT documented bilateral horizontal canal dysfunction with decreased gain and corrective saccades. Caloric irrigation and rotation chair testing revealed prominent bilateral horizontal canal paresis. Patients with WE also had decreased spatial memory, which substantially recovered after treatments. Functional connections at the predefined seed regions, including the insular cortex and parietal operculum, were attenuated in the WE group compared to healthy controls. Conclusions: WE is related to impaired VOR and visuospatial dysfunction, and fMRI documented changes in the rs-fc of multisensory vestibular processing regions including the insula, parietal operculum, and superior temporal gyrus, which participate in integration of vestibular perception.

Cognition in adults with Williams syndrome-A 20-year follow-up study

Background

Williams syndrome (WBS) is a genetic multisystem disorder. The main symptom is borderline (intelligence quotient, IQ 70–79) or abnormally low intelligence (IQ < 70). According to earlier studies young individuals with WBS demonstrate generally a slightly higher verbal IQ (VIQ) compared to performance/nonverbal IQ (PIQ). WBS was recognized as a distinct entity already about 60 years ago, but still cognition in adults with WBS is poorly known.

Methods

We followed 25 adults (age at baseline 19–68, median 38) with genetically confirmed WBS for about 20 years. The study subjects underwent medical and neuropsychological assessments at the baseline and at the end of follow‐up.

Results

The mean VIQ remained quite stable from early adulthood up to 40 years of age after which it declined. The mean PIQ kept on improving from early adulthood until 50 years of age after which it gradually declined. At the end of the study, all study subjects had at least two longstanding health problems out of which hypertension, psychiatric disorder, and scoliosis or kyphosis occurred most frequently. At end of the study, two patients suffered from vascular dementia. Seven patients died during the follow‐up.

Conclusions

In adults with WBS, the course of cognition is uneven across the cognitive profile. Their verbal functions both develop and deteriorate earlier than performance/nonverbal functions. Frequent somatic co‐morbidities may increase risk to shortened life span.

Change in Cognitive Performance From Midlife Into Old Age: Findings from the Midlife in the United States (MIDUS) Study

OBJECTIVES

A substantial body of research has documented age-related declines in cognitive abilities among adults over 60, yet there is much less known about changes in cognitive abilities during midlife. The goal was to examine longitudinal changes in multiple cognitive domains from early midlife through old age in a large national sample, the Midlife in the United States (MIDUS) study.

METHODS

The Brief Test of Adult Cognition by Telephone (BTACT) was administered on two occasions (MIDUS 2, MIDUS 3), an average of 9 years apart. At MIDUS 3, those with the cognitive assessment (N=2518) ranged in age from 42 to 92 years (M=64.30; SD=11.20) and had a mean education of 14.68 years (SD=2.63). The BTACT includes assessment of key aging-sensitive cognitive domains: immediate and delayed free recall, number series, category fluency, backward digit span, processing speed, and reaction time for attention switching and inhibitory control, which comprise two factors: episodic memory and executive functioning.

RESULTS

As predicted, all cognitive subtests and factors showed very small but significant declines over 9 years, with differences in the timing and extent of change. Processing speed showed the earliest and steepest decrements. Those with higher educational attainment scored better on all tests except reaction time. Men had better executive functioning and women performed better on episodic memory.

CONCLUSIONS

Examining cognitive changes in midlife provides opportunities for early detection of cognitive impairments and possibilities for preventative interventions. (JINS, 2018, 24, 805-820).

Genetic and Environmental Influences on Verbal Fluency in Middle Age: A Longitudinal Twin Study

Mounting evidence suggests that measures of phonemic fluency and semantic fluency are differentially associated with other cognitive and health phenotypes, but few studies have examined their shared and unique variance, especially using genetically-informative designs. In this study, 1464 middle-aged twins completed six fluency subtests at up to two time-points (mean age 56 and 62 years). Confirmatory factor analyses supported a two-factor solution: a General Fluency latent factor explained variation in all six subtests and a Semantic-Specific factor accounted for additional variance in semantic subtests. Both factors were explained primarily by genetic influences at both waves (a2 = 0.57-0.76). There was considerable stability of individual differences over 6 years (r = .90 for General Fluency, r = .81 for Semantic-Specific), especially for genetic influences (rg = .94 and 1.0, respectively). These results suggest that semantic fluency can be viewed as a combination of general and semantic-specific variance, but phonemic fluency is captured entirely by the general factor.

Education Does Not Affect Cognitive Decline in Aging: A Bayesian Assessment of the Association Between Education and Change in Cognitive Performance

Education is positively associated with level of cognitive function but the association between education and rate of cognitive decline remains unresolved, partly for methodological reasons. In this article, we address this issue using linear mixed models and Bayesian hypothesis testing, using data from the Betula cohort-sequential longitudinal study. Our results support the null hypothesis that education does not alter the rate of cognitive decline for visuospatial ability, semantic knowledge, and episodic memory. We propose that education is only a relevant variable for understanding cognitive performance in older age because of the association between performance and education that is formed in early development.

Underdiagnosis of mild cognitive impairment: A consequence of ignoring practice effects

INTRODUCTION

Longitudinal testing is necessary to accurately measure cognitive change. However, repeated testing is susceptible to practice effects, which may obscure true cognitive decline and delay detection of mild cognitive impairment (MCI).

METHODS

We retested 995 late-middle-aged men in a ∼6-year follow-up of the Vietnam Era Twin Study of Aging. In addition, 170 age-matched replacements were tested for the first time at study wave 2. Group differences were used to calculate practice effects after controlling for attrition effects. MCI diagnoses were generated from practice-adjusted scores.

RESULTS

There were significant practice effects on most cognitive domains. Conversion to MCI doubled after correcting for practice effects, from 4.5% to 9%. Importantly, practice effects were present although there were declines in uncorrected scores.

DISCUSSION

Accounting for practice effects is critical to early detection of MCI. Declines, when lower than expected, can still indicate practice effects. Replacement participants are needed for accurately assessing disease progression.

Continuity of cognitive change across adulthood

Although cross-sectional (between-person) comparisons consistently reveal age-related cognitive declines beginning in early adulthood, significant declines in longitudinal (within-person) comparisons are often not apparent until age 60 or later. The latter results have led to inferences that cognitive change does not begin until late middle age. However, because mean change reflects a mixture of maturational and experiential influences whose contributions could vary with age, it is important to examine other properties of change before reaching conclusions about the relation of age to cognitive change. The present study was designed to examine measures of the stability, variability, and reliability of change, as well as correlations of changes in memory with changes in speed in 2,330 adults between 18 and 80 years of age. Despite substantial power to detect small effects, the absence of significant age differences in these properties suggests that cognitive change represents a qualitatively similar phenomenon across a large range of adulthood.

Mechanisms behind distracted driving behavior: The role of age and executive function in the engagement of distracted driving

Performing secondary tasks, such as texting while driving, is associated with an increased risk of motor vehicle collisions (MVCs). While cognitive processes, such as executive function, are involved in driving, little is known about the relationship between executive control and willingness to engage in distracted driving. This study investigated the relationship between age, behavioral manifestations of executive function, and self-reported distracted driving behaviors. Executive difficulty (assessed with the BRIEF-A) as well as demographics (age and gender) was considered as possible predictors of engagement in distracted driving behaviors. Fifty-nine young, middle, and older adults self-reported executive difficulty and weekly engagement in distracted driving behaviors. Results revealed that while partially accounted for by age, global executive difficulty was uniquely related to engagement in distracted driving behaviors. Older age was associated with fewer weekly self-reported distracted driving behaviors while higher self-reported executive difficulty was associated with more frequent weekly engagement in distracted behavior. No significant differences were found between young and middle-aged adults on distracted driving behaviors. Findings conclude that distracted driving is a ubiquitous phenomenon evident in drivers of all ages. Possible mechanisms underlying distracted driving behavior could potentially be related to deficits in executive function.

Social Network Size and Cognitive Functioning in Middle-Aged Adults: Cross-Sectional and Longitudinal Associations

The objective of the present study was to examine relations between social network size and three cognitive abilities (episodic memory, semantic memory, visuospatial ability) in middle-aged adults. We analyzed cross-sectional data on social network size and cognitive functioning that were available for 804 participants aged 40–60 years. In addition, we examined 5- and 10-year follow-up measurements of cognitive functioning that were available for 604 and 255 participants, respectively. Cross-sectional analyses revealed a positive association between social network size and each of the three cognitive abilities. Baseline network size was positively related to 5-year changes in semantic memory, and to 10-year changes in semantic as well as episodic memory, but was unrelated to changes in visuospatial performance. A minor portion of the sample (n = 131) had 10-year follow-up data on network size. Cross-lagged panel correlations revealed that baseline network size was associated with follow-up measurement in cognitive functioning (episodic memory, semantic memory), whereas baseline cognitive performance was unrelated to future network size. Together, the results demonstrate a small but positive relation between network size and declarative memory abilities, in line with models proposing a cognitive reserve built up by factors such as the increased cognitive stimulation associated with a more extensive social network.

How Much Does WAIS-IV Perceptual Reasoning Decline Across the 20 to 90-Year Lifespan When Processing Speed is Controlled?

The most prominent pattern of cognitive change over the lifespan centers on the difference between patterns of maintained abilities on tests of crystallized knowledge and patterns of steady decline on tests of problem solving and processing speed. Whereas the maintained-vulnerable dichotomy is well established in the literature, questions remain about cognitive decline in problem solving when processing speed is controlled. This relationship has been examined in cross-sectional studies that typically used non-clinical tests with non-representative samples of adults. This study extended these findings to the most popular clinical test, the Wechsler Adult Intelligence Scale -4th ed. (WAIS-IV), using its carefully stratified sample as the source of data (ages 20-90 for Indexes, ages 16-90 for Perceptual Reasoning subtests). Multivariate Analysis of Covariance (MANCOVA) revealed that 70-80% of the variance in declining reasoning ability was shared with the speed factor. This was true (a) on the index and subtest level and (b) regardless of the type of problem-solving task employed. Such robust findings have important clinical and research implications for neuropsychologists, who most frequently use the Wechsler scales as part of their assessment battery.

Comparing individual differences in inconsistency and plasticity as predictors of cognitive function in older adults

INTRODUCTION

Recent theorizing differentiates key constraints on cognition, including one's current range of processing efficiency (i.e., flexibility or inconsistency) as well as the capacity to expand flexibility over time (i.e., plasticity). The present study uses intensive assessment of response time data to examine the interplay between markers of intraindividual variability (inconsistency) and gains across biweekly retest sessions (plasticity) in relation to age-related cognitive function.

METHOD

Participants included 304 adults (aged 64 to 92 years: M = 74.02, SD = 5.95) from Project MIND, a longitudinal burst design study assessing performance across micro and macro intervals (response latency trials, weekly bursts, annual retests). For two reaction time (RT) measures (choice RT and one-back choice RT), baseline measures of RT inconsistency (intraindividual standard deviation, ISD, across trials at the first testing session) and plasticity (within-person performance gains in average RT across the 5 biweekly burst sessions) were computed and were then employed in linear mixed models as predictors of individual differences in cognitive function and longitudinal (6-year) rates of cognitive change.

RESULTS

Independent of chronological age and years of education, higher RT inconsistency was associated uniformly with poorer cognitive function at baseline and with increased cognitive decline for measures of episodic memory and crystallized verbal ability. In contrast, predictive associations for plasticity were more modest for baseline cognitive function and were absent for 6-year cognitive change.

CONCLUSIONS

These findings underscore the potential utility of response times for articulating inconsistency and plasticity as dynamic predictors of cognitive function in older adults.

Age Differences and Educational Attainment Across the Life Span on Three Generations of Wechsler Adult Scales

Patterns of maintenance of ability across the life span have been documented on tests of knowledge ( Gc), as have patterns of steady decline on measures of reasoning ( Gf/Gv), working memory ( Gsm), and speed ( Gs). Whether these patterns occur at the same rate for adults from different educational backgrounds has been debated. In addition, age-related research is needed to study global IQs, especially in view of the increased reliance on IQ in capital punishment court cases. In this study, large representative samples of adults tested during the standardizations of three versions of the Wechsler Adult Intelligence Scale (WAIS) served as subjects: WAIS-R ( N = 1,480, ages 20-74), WAIS-III ( N = 2,093, ages 20-90), and WAIS-IV ( N = 1,800, ages 20-90). Based on regression analysis, patterns of aging on Full Scale IQ (FSIQ) and the four abilities (a) were essentially the same for males versus females and (b) characterized all levels of education across three generations of Wechsler’s adult scales.

Predictors of Retest Effects in a Longitudinal Study of Cognitive Aging in a Diverse Community-Based Sample

Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, literacy, and dementia risk factors including apolipoprotein E ε4 status, baseline cognitive performance, and cardiovascular risk. We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. The mean retest effect for general cognitive performance was 0.60 standard deviations (95% confidence interval [0.46, 0.74]), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance (many of whom met criteria for dementia based on a study algorithm), consistent with regression to the mean. Retest did not differ by other characteristics. Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research.

Visuospatial characteristics of an elderly Chinese population: results from the WAIS-R block design test

Visuospatial deficits have long been recognized as a potential predictor of dementia, with visuospatial ability decline having been found to accelerate in later stages of dementia. We, therefore, believe that the visuospatial performance of patients with mild cognitive impairment (MCI) and dementia (Dem) might change with varying visuospatial task difficulties. This study administered the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Block Design Test (BDT) to determine whether visuospatial ability can help discriminate between MCI patients from Dem patients and normal controls (NC). Results showed that the BDT could contribute to the discrimination between MCI and Dem. Specifically, simple BDT task scores could best distinguish MCI from Dem patients, while difficult BDT task scores could contribute to discriminating between MCI and NC. Given the potential clinical value of the BDT in the diagnosis of Dem and MCI, normative data stratified by age and education for the Chinese elderly population are presented for use in research and clinical settings.

Age-related differences in multiple task monitoring

Coordinating multiple tasks with narrow deadlines is particularly challenging for older adults because of age related decline in cognitive control functions. We tested the hypothesis that multiple task performance reflects age- and gender-related differences in executive functioning and spatial ability. Young and older adults completed a multitasking session with four monitoring tasks as well as separate tasks measuring executive functioning and spatial ability. For both age groups, men exceeded women in multitasking, measured as monitoring accuracy. Individual differences in executive functioning and spatial ability were independent predictors of young adults' monitoring accuracy, but only spatial ability was related to sex differences. For older adults, age and executive functioning, but not spatial ability, predicted multitasking performance. These results suggest that executive functions contribute to multiple task performance across the adult life span and that reliance on spatial skills for coordinating deadlines is modulated by age.

Aging Cognition Unconfounded by Prior Test Experience

OBJECTIVE

Investigate time-related age differences in cognitive functioning without influences of prior test experience.

METHODS

Cognitive scores were compared in different individuals from the same birth years who were tested in different years, when they were at different ages. These types of quasi-longitudinal comparisons were carried out on data from three large projects: the Seattle Longitudinal Study [Schaie, K. W. (2013). Developmental influences on adult intelligence: The Seattle Longitudinal Study (2nd ed.). New York, NY: Oxford University Press], the Betula Project [Ronnlund, M., & Nilsson, L-G. (2008). The magnitude, generality, and determinants of Flynn effects on forms of declarative memory and visuospatial ability: Time-sequential analyses of data from a Swedish cohort study. Intelligence, 36, 192-209], and the Virginia Cognitive Aging Project (this study).

RESULTS

In each data set, the results revealed that the estimates of cognitive change with no prior test experience closely resembled the estimates of age relations based on cross-sectional comparisons. Furthermore, longitudinal comparisons revealed positive changes at young ages that gradually became more negative with increased age, whereas all of the estimates of change without prior test experience were negative except those for measures of vocabulary.

DISCUSSION

The current results suggest that retest effects can distort the mean age trends in longitudinal comparisons that are not adjusted for experience. Furthermore, the findings can be considered robust because the patterns were similar across three data sets involving different samples of participants and cognitive tests, and across different methods of controlling experience effects in the new data set.

Why are there different age relations in cross-sectional and longitudinal comparisons of cognitive functioning?

A major challenge for researchers interested in investigating relations between aging and cognitive functioning is distinguishing influences of aging from other determinants of cognitive performance. For example, cross-sectional comparisons may be distorted because people of different ages were born and grew up in different time periods, and longitudinal comparisons may be distorted because performance on a second occasion is influenced by the experience of performing the tests on the first occasion. One way in which these different types of influences might be investigated is with research designs involving comparisons of people of different ages from the same birth cohorts who are all tested for the first time in different years. Results from several recent studies using these types of designs suggest that the age trends in some cognitive abilities more closely resemble those from cross-sectional comparisons than those from longitudinal comparisons. These findings imply that a major reason for different age trends in longitudinal and cross-sectional comparisons of cognitive functioning is that the prior experience with the tests inflates scores on the second occasion in longitudinal studies.

The robust reliability of neuropsychological measures: meta-analyses of test-retest correlations

Test-retest reliability is an important psychometric property relevant to assessment instruments typically used in neuropsychological assessment. This review presents a quantitative summary of test-retest reliability coefficients for a variety of widely used neuropsychological measures. In general, the meta-analytic test-retest reliabilities of the test scores ranged from adequate to high (i.e., r=.7 and higher). Furthermore, the reliability values were largely robust across factors such as age, clinical diagnosis, and the use of alternate forms. The values for some of the memory and executive functioning scores were lower (i.e., less than r=.7). Some of the possible reasons for these lower values include ceiling effects, practice effects, and across time variability in cognitive abilities measured by those tests. In general, neuropsychologists who use these measures in their assessments can be encouraged by the magnitude of the majority of the meta-analytic test-retest correlations obtained.

Effects of perceived long-term stress on subjective and objective aspects of memory and cognitive functioning in a middle-aged population-based sample

The longitudinal effects of perceived stress on measures of memory and two other cognitive functions (word fluency, visuospatial ability) in a middle-aged sample (40-60 years, M age = 47.1 years, SD = 6.1 years; n = 192) were examined. A group describing themselves as stressed in general at baseline, and at follow-up measurement 5 and 10 years later (n = 96) was compared with a matched (age, sex) low-stress group (n = 96). The results revealed more depressive symptoms over time in the high-stress group. With regard to memory, a dissociation between subjective and objective measures was observed. Specifically, participants in the high-stress group rated their memory as worse over time as compared with controls, and reported a higher frequency of occurrence of everyday memory failures, effects partly independent of depressive symptoms. However, the groups did not differ in terms of objective episodic memory performance, word fluency or block design performance, with stable levels of performance over time regardless of perceived stress. The lack of effects of stress on cognitive performance is discussed in the light of factors such as stress level, age of the participants, and other individual difference factors.