Effects of death within 11 years on cognitive performance in old age

Exploring cognitive progression subtypes in the Framingham Heart Study

INTRODUCTION

Alzheimer's disease (AD) is a heterogeneous disorder characterized by complex underlying neuropathology that is not fully understood. This study aimed to identify cognitive progression subtypes and examine their correlation with clinical outcomes.

METHODS

Participants of this study were recruited from the Framingham Heart Study. The Subtype and Stage Inference (SuStaIn) method was used to identify cognitive progression subtypes based on eight cognitive domains.

RESULTS

Three cognitive progression subtypes were identified, including verbal learning (Subtype 1), abstract reasoning (Subtype 2), and visual memory (Subtype 3). These subtypes represent different domains of cognitive decline during the progression of AD. Significant differences in age of onset among the different subtypes were also observed. A higher SuStaIn stage was significantly associated with increased mortality risk.

DISCUSSION

This study provides a characterization of AD heterogeneity in cognitive progression, emphasizing the importance of developing personalized approaches for risk stratification and intervention.

Highlights

We used the Subtype and Stage Inference (SuStaIn) method to identify three cognitive progression subtypes.Different subtypes have significant variations in age of onset.Higher stages of progression are associated with increased mortality risk.

Is simple reaction time or choice reaction time an indicator of all-cause mortality or CVD mortality?

OBJECTIVES

Simple reaction time (SRT) and choice reaction time (CRT) have been shown to be good indicators for quantitatively assessing the level of human cognitive impairment, but these parameters have also been linked to the risk of human death. This study aimed to quantitatively assess the independent predictive value of SRT or CRT for all-cause mortality or cardiovascular disease (CVD) mortality by conducting a meta-analysis of prospective studies.

STUDY DESIGN

The study design of this study is a prospective cohort study.

METHODS

We conducted a meta-analysis by combining hazard ratios (HRs) and 95% confidence intervals (95% CIs) of SRT or CRT with all-cause mortality or CVD mortality in healthy community residents aged 18 and over. Heterogeneity was evaluated by using Q statistics and Cochrane's I² statistics.

RESULTS

A total of seven prospective studies that examined all-cause mortality and CVD mortality were included. The pooled HR of all-cause mortality in SRT was 1.099 (1.065-1.134, I² = 11.9%), and an increased risk of CVD mortality was associated with lower SRT (HR = 1.186, 95% CI = 1.137-1.236; I² = 52.4%). Similarly, the pooled HR of all-cause mortality in CRT was 1.140 (95% CI = 1.085-1.197, I² = 33.7%). However, lower CRT was not statistically associated with an increased risk of CVD mortality.

CONCLUSION

SRT may be a predictor of all-cause-mortality and CVD mortality, and CRT is significantly associated with an increased risk of all-cause mortality.

Understanding the relationship between cognition and death: a within cohort examination of cognitive measures and mortality

Despite several studies demonstrating an independent and inverse association between cognition and mortality, the nature of this association still remains unclear. To examine the association of cognition and mortality after accounting for sociodemographic, health and lifestyle factors and to explore both test and population characteristics influencing this relationship. In a population based cohort of 8585 men and women aged 48-92 years, who had cognitive assessments in 2006-2011 and were followed up till 2016 for mortality, we examined the relationship between individual cognitive tests as well as a global cognition score to compare their ability in predicting mortality and whether these differed by population characteristics. Risk of death was estimated using Cox proportional hazard regression models including sociodemographic, lifestyle and health variables, and self-reported comorbidities, as covariates in the models. Poor cognitive performance (bottom quartile of combined cognition score) was associated with higher risk of mortality, Hazard Ratio = 1.32 (95% Confidence Interval 1.09, 1.60); individual cognitive tests varied in their mortality associations and also performed differently in middle-age and older age groups. Poor cognitive performance is independently associated with higher mortality. This association is observed for global cognition and for specific cognitive abilities. Associations vary depending on the cognitive test (and domain) as well as population characteristics, namely age and education.

Performance on Specific Cognitive Domains and Cause of Death: A Prospective Population-Based Study in Non-Demented Older Adults (NEDICES)

Evidence regarding the relationship between performance on specific cognitive domains and cause of death is scarce. We assessed whether specific cognitive domains predicted mortality and the presence of any association with specific causes of death in a population-dwelling sample of non-demented older adults. In this population-based, prospective study (NEDICES), 2,390 non-demented subjects ≥65 years completed a brief neuropsychological battery. Cox's proportional hazards models, adjusted by sociodemographic and comorbidity factors, global cognitive performance, educational level, and premorbid intelligence were used to assess the risk of death. Participants were followed for a median of 9.2 years (range 0.01-10.7), after which the death certificates of those who died were examined. 880 (36.8%) of 2,390 participants died over a median follow-up of 5.5 years (range 0.01-10.5). Using adjusted Cox regression models, we found that hazard ratios for mortality in participants within the lowest tertiles (worse performance) were 1.31 (speed of cognitive processing, p = 0.03); 1.22 (semantic fluency, p = 0.04), 1.32 (delayed free recall, p = 0.003), and 1.23 (delayed logical memory, p = 0.03). Poor performance on delayed recall and speed of cognitive processing tests were associated with dementia and cerebrovascular disease mortality, respectively. Further, poor performance on semantic fluency was associated with decreased cancer mortality. In this study of community dwelling non-demented older adults, worse neuropsychological performance was associated with increased risk of mortality. Performance on specific cognitive domains were related to different causes of death. Of particular note there appears to be an inverse association between poor semantic fluency and cancer mortality.

Effect of successful aging on mortality in older individuals: The PALA study

The definition of successful aging and identification of predictors have been extensively reviewed, less attention however, has been given to the role of this condition on mortality.

Physical activity and physical functioning in Swedish and Iranian 75-year-olds - a comparison

BACKGROUND AND PURPOSE

The pattern of population aging is highly complex and contextually based. Cross-national comparisons are helpful to explore related factors. Two cross-sectional studies designed to compare physical activity level, physical functioning and certain health related factors in 75-year-old women and men in Sweden and Iran.

MATERIALS AND METHODS

Cohorts of 637 Swedish and 851 Iranian 75-year-olds were investigated with the same methods regarding physical activity level, physical functioning and health related factors.

RESULTS

There were differences in physical activity level (p<0.001), self-reported physical functioning (p<0.001) objective physical functioning (p<0.001), health status (p<0.001) and most socio-demographic aspects between the two countries. Here the Swedish cohort had the advantage. There was no difference between the countries regarding prevalence of vertigo or falls. The only variables where the Iranian cohort had advantage over the Swedes were grip strength and smoking habits. There were larger gender differences in walking habits, self-selected walking speed, timed chair stand, and one-leg stance in Iran, and in grip strength in Sweden, all to the disadvantage of women.

CONCLUSIONS

Iranian 75-years-olds had a lower physical activity level, a worse lower extremity physical function but a better grip strength, a worse physical health status, but smoked less than their Swedish counterparts. Despite this, there were no differences regarding vertigo or falls. In most aspects, the magnitude of gender differences was about the same and in disadvantage of women, although there were larger differences in Iran in some lower extremity functions.

Terminal pathologies affect rates of decline to different extents and age accelerates the effects of terminal pathology on cognitive decline

OBJECTIVES

To test whether different terminal pathologies are associated with different rates of age-related decline in fluid and crystallized mental abilities and whether pathology-associated declines are accelerated by age.

METHODS

During a 20-year longitudinal study, 6203 participants were quadrennially assessed on the Heim's (Heim, A 1970) The AH4 series of intelligence tests Slough, U.K.: NEP) AH4-1 and AH4-2 tests of fluid intelligence and on the Raven's (Raven, J. C. 1965) The Mill Hill Vocabulary Scale London: H.K. Lewis) Mill Hill A and B tests of recognition and production vocabulary. Dates and proximate causes of death were logged for 2499 participants. Multilevel modelling compared rates of decline after effects of sex, demographics, and practice were taken into consideration.

RESULTS

Rates of cognitive decline markedly differed across pathologies, being most rapid for dementias and infections, slower for malignancies, and most prolonged for cardiovascular conditions. Pathologies were associated with faster declines in older individuals.

DISCUSSION

After sex, age, and demographics have also been considered, different terminal pathologies are associated with markedly different rates of decline. Age accelerates pathology-related decline. This raises the further question as to whether any, or how much of, age-related cognitive decline is brought about by other causes than an increasing burden of pathologies.

Aging and the shape of cognitive change before death: terminal decline or terminal drop?

OBJECTIVES

Relative to typical age-related cognitive decrements, the terms "terminal decline" and "terminal drop" refer to the phenomenon of increased cognitive decline in proximity to death. Given that these terms are not necessarily synonymous, we examined the important theoretical distinction between the two alternative trajectories or shapes of changes they imply.

METHODS

We used 12-year (5-wave) data from the Victoria Longitudinal Study to directly test whether pre-death cognitive decrements follow a terminal decline (generally gradual) or a terminal drop (more abrupt) shape. Pre-death trajectories of cognitive decline for n=265 decedents (Mage = 72.67 years, SD = 6.44) were examined separately for 5 key cognitive constructs (verbal speed, working memory, episodic memory, semantic memory, and crystallized ability).

RESULTS

Several classes of linear mixed models evaluated whether cognitive decline increased per additional year closer to death. Findings indicated that the shape of pre-death cognitive change was predominantly characterized by decline that is steeper as compared with typical aging-related change, but still best described as slow and steady decline, especially as compared with precipitous drop.

DISCUSSION

The present findings suggest that terminal decline and terminal drop trajectories may not be mutually exclusive but could rather reflect distinct developmental trajectories within the same individual.

Executive function (capacity for behavioral self-regulation) and decline predicted mortality in a longitudinal study in Southern Colorado

OBJECTIVE

To assess the relationship between mortality and impairment and decline in a specific executive cognitive function, the capacity for behavioral self-regulation.

STUDY DESIGN AND SETTING

This study examined the association between mortality and baseline and 22-month decline in the capacity for behavioral self-regulation, as measured by the Behavioral Dyscontrol Scale, among 1,293 participants of the San Luis Valley Health and Aging Study (SLVHAS), a population-based longitudinal study. The Behavioral Dyscontrol Scale and a measure of overall mental status, the Mini-Mental State Examination, were administered at baseline and follow-up interviews. Cox regression was used to examine baseline and decline in capacity for behavioral self-regulation as possible predictors of mortality.

RESULTS

Baseline Behavioral Dyscontrol Scale score was predictive of mortality, independent of demographics and comorbidity count (hazard ratio [HR]=1.07; 95% confidence interval [CI]: 1.04, 1.09). It remained a significant predictor with further adjustment for Mini-Mental State Examination score. Decline in this specific executive cognitive function was associated with mortality after adjustment for covariates and baseline cognitive scores (HR=1.09; 95% CI: 1.04, 1.13).

CONCLUSION

Thus, both baseline capacity for behavioral self-regulation and its decline over time predicted mortality in the SLVHAS cohort. These associations may partly be attributed to maintaining the ability for self-care. Understanding how specific forms of impairment contribute to mortality may help identify patients who could benefit from early intervention.

Cognition and mortality from the major causes of death: the Health and Lifestyle Survey

OBJECTIVE

To investigate the influence of reaction time and cognition on the risk of death from cause-specific mortality and to examine whether any association found remains after adjustment for available socioeconomic, lifestyle, and health factors.

METHODS

Participants were from the UK Health and Lifestyle Survey. The sample consisted of 6424 community dwelling individuals aged between 18 and 97 years at baseline (1984/1985). Sociodemographic, lifestyle, health, and physiological information was collected alongside cognitive testing which included simple (SRT) and choice (CRT) reaction time, a short-term memory test, and a test of visual-spatial reasoning. Participants have been followed for 21 years for cause-specific mortality.

RESULTS

Slower and more variable reaction times and poorer cognitive performance were associated with a higher risk of death from cardiovascular disease, stroke, and respiratory disease after controlling for age and sex. Slight attenuation was noted after adjustments for all covariates. However, only CRT mean remained significantly associated with death from respiratory disease. No associations were found for coronary heart disease, lung cancer, and all nonlung cancers. Significant cognition-mortality associations were mostly obtained in those aged over 60 years. The possibility of reverse causality was partly excluded by reanalysing the data after omitting individuals who died within 5 years of cognitive testing.

CONCLUSIONS

Slower and more variable reaction times and poorer cognitive performance were related to an increased risk of mortality from cardiovascular disease, stroke, and respiratory disease. The possibility of reverse causality requires further testing.

Does cognition predict mortality in midlife? Results from the Whitehall II cohort study

The authors examined the association of 'g' (general intelligence) factor and five specific cognitive measures assessed in 1997-1999 with mortality till 2006 (mean follow-up of 8 years) in the middle-aged Whitehall II cohort study. In age- and sex-adjusted analysis, a decrease in 1 S.D. in memory (hazard ratio (HR), 1.19; 95% confidence interval (CI): 1.02, 1.39) and in Alice Heim 4-I (AH4-I) (HR, 1.16; 95% CI: 1.01, 1.35) was found to be associated with higher mortality. The association with 'g' factor, phonemic and semantic fluency did not reach significance at p<0.05. No association was found with vocabulary. Out of education, health behaviours and health measures, it was health behaviours that explained the greater part of the association between cognition and mortality, ranging from 21% for memory to 70% for semantic fluency. All the covariates taken together explained only 26% of the association with memory and between 33 and 90% for the other cognitive measures. This study suggests that 'g' type composite measure of cognition might not be enough to understand the associations between cognition and health.

A comparison of parametric models for the investigation of the shape of cognitive change in the older population

BACKGROUND

Cognitive decline is a major threat to well being in later life. Change scores and regression based models have often been used for its investigation. Most methods used to describe cognitive decline assume individuals lose their cognitive abilities at a constant rate with time. The investigation of the parametric curve that best describes the process has been prevented by restrictions imposed by study design limitations and methodological considerations. We propose a comparison of parametric shapes that could be considered to describe the process of cognitive decline in late life. Attrition plays a key role in the generation of missing observations in longitudinal studies of older persons. As ignoring missing observations will produce biased results and previous studies point to the important effect of the last observed cognitive score on the probability of dropout, we propose modelling both mechanisms jointly to account for these two considerations in the model likelihood.

METHODS

Data from four interview waves of a population based longitudinal study of the older population, the Cambridge City over 75 Cohort Study were used. Within a selection model process, latent growth models combined with a logistic regression model for the missing data mechanism were fitted. To illustrate advantages of the model proposed, a sensitivity analysis of the missing data assumptions was conducted.

RESULTS

Results showed that a quadratic curve describes cognitive decline best. Significant heterogeneity between individuals about mean curve parameters was identified. At all interviews, MMSE scores before dropout were significantly lower than those who remained in the study. Individuals with good functional ability were found to be less likely to dropout, as were women and younger persons in later stages of the study.

CONCLUSION

The combination of a latent growth model with a model for the missing data has permitted to make use of all available data and quantify the effect of significant predictors of dropout on the dropout and observational processes. Cognitive decline over time in older persons is often modelled as a linear process, though we have presented other parametric curves that may be considered.

Estimating age change in list recall in asset and health dynamics of the oldest-old: the effects of attrition bias and missing data treatment

Average change in list recall was evaluated as a function of missing data treatment (Study 1) and dropout status (Study 2) over ages 70 to 105 in Asset and Health Dynamics of the Oldest-Old data. In Study 1 the authors compared results of full-information maximum likelihood (FIML) and the multiple imputation (MI) missing-data treatments with and without independent predictors of missingness. Results showed declines in all treatments, but declines were larger for FIML and MI treatments when predictors were included in the treatment of missing data, indicating that attrition bias was reduced. In Study 2, models that included dropout status had better fits and reduced random variance compared with models without dropout status. The authors conclude that change estimates are most accurate when independent predictors of missingness are included in the treatment of missing data with either MI or FIML and when dropout effects are modeled.

Distinguishing Preterminal and Terminal Cognitive Decline

This paper reviews different methodological approaches taken to examine terminal decline in cognitive function, and presents new findings from the Bronx Aging Study (BAS). Numerous approaches have been taken to assess mortality effects on cognition: comparing survivors and decedents level and rate of change in cognition, and identifying individual differences in cognition associated with time-to-death. However, few studies have actually modeled within-person change in cognition as a function of time-to-death. Using linear mixed models with a change point, intraindividual change in episodic memory was modeled as a function of both age and time-to-death. A dramatic increase in the rate of decline was identified at 8.4 years prior to death, providing clear evidence of a terminal-decline phase that is much longer than previously estimated. These results emphasize the importance of modeling the time course and effects of terminal cognitive decline for understanding cognitive change in aging adults.

The Relationship Between Cognition and Mortality in Patients with Stroke, Coronary Heart Disease, or Cancer

Numerous studies have reported an association between cognitive impairment and an increased risk for mortality. Most results are from large epidemiological studies and control for medical conditions that may relate to cognitive decline, as well as an increased mortality risk. The aim of this review was to evaluate the association between cognitive performance and mortality within patient samples of stroke, cancer, or coronary heart disease. After reviewing the PubMed literature for articles on stroke, cancer, and cardiovascular related illnesses, 47 longitudinal studies were identified that met the cognition/mortality search criteria. In general, the results demonstrated that within the clinical groups studied, cognitive performance and cognitive impairment both predict mortality, although results were less consistent for coronary heart disease. This study adds further support for the ubiquity of the association of cognitive performance with health outcomes and mortality. Optimizing health has implications for both cognitive performance and longevity.

Understanding Terminal Decline in Cognition and Risk of Death

There is new empirical evidence that the effects of impending death on cognition have been miscalculated because of neglect of the incidence of dropout and of practice gains during longitudinal studies. When these are taken into consideration, amounts and rates of cognitive declines preceding death and dropout are seen to be almost identical, and participants aged 49 to 93 years who neither dropout nor die show little or no decline during a 20-year longitudinal study. Practice effects are theoretically informative. Positive gains are greater for young and more intelligent participants and at all levels of intelligence and durations of practice; declines in scores of 10% or more between successive quadrennial test sessions are risk factors for mortality. Higher baseline intelligence test scores are also associated with reduced risk of mortality, even when demographics and socioeconomic advantage have been taken into consideration.

Longitudinal Cognition-Survival Relations in Old and Very Old Age

We use a statistical model that combines longitudinal and survival analyses to estimate the influence of level and change in cognition on age at death in old and very old individuals. Data are from the Berlin Aging Study, in which an initial sample of 516 elderly individuals with an age range of 70 to 103 years was assessed up to 11 times across a period of up to 13 years. Four cognitive ability domains were assessed by two variables each: perceptual speed (Digit Letter and Identical Pictures), episodic memory (Paired Associates and Memory for Text), fluency (Categories and Word Beginnings), and verbal knowledge (Vocabulary and Spot-a-Word). Longitudinal models on cognition controlled for dementia diagnosis and retest effects, while survival models on age at death controlled for age, sex, socioeconomic status, sensory and motor performance, and broad personality characteristics. Results indicate: (1) Individual differences in the level of and in the linear change in performance are present for all cognitive variables; (2) when analyzed independently of cognitive performance, all covariates, except broad personality factors, predict survival; (3) when cognitive performance is accounted for, age, sex, and motor performance do predict survival, while socioeconomic status and broad personality factors do not, and sensory performance does only at times; (4) when cognitive variables are analyzed independently of each other, both level and change in speed and fluency, as well as level in memory and knowledge predict survival; (5) when all cognitive variables are analyzed simultaneously using a two-stage procedure, none of them is significantly associated to survival. In agreement with others, our findings suggest that survival is related to cognitive development in old and very old age in a relatively global, rather than ability-specific, manner.

Aging and Late-Life Terminal Decline in Perceptual Speed

Individual changes in perceptual speed were modeled as a conditional function of age and time-to-death. Alternative time-structured models were evaluated in a Swedish population-based, age-homogeneous sample (Gothenburg H70; N = 764) of individuals assessed at ages 70, 75, 79, 85, 88, 90, 92, 95, 97, and 99. Modeling time as proximity to death accounted better for the heterogeneity of individual changes than an age-based time structure. Time-to-death was a significant predictor of individual differences in rates of change in the age-based model but age did not significantly predict individual differences in rates of change in the model structured by proximity to death. In both the age-based and death-based time-structured models, accelerated changes prior to time of death were observed and provide support for the terminal-decline hypothesis. Identification of health-related factors and other sources of causal heterogeneity of aging-related change can make productive use of alternative time specifications that emphasize congruency between within-person change processes and aggregate population change.

Change in object naming ability during adulthood

Using longitudinal data on the Boston Naming Test ( Kaplan, Goodglass, & Weintraub, 1983) collected over 20 years from healthy individuals aged 30 to 94, we examined change in lexical retrieval with age, gender, education, and their interactions. We compared results between random-effects longitudinal and traditional cross-sectional models. Random-effects modeling revealed significant linear and quadratic change in lexical retrieval with age; it also showed a Gender x Education interaction, indicating poorest performance for women with less education. Cross-sectional analyses produced greater estimates of change with age than did longitudinal analyses.

Change in cognitive capabilities in the oldest old: the effects of proximity to death in genetically related individuals over a 6-year period

Change in cognitive abilities was assessed over a 6-year period in a sample of monozygotic and same-sex dizygotic twin pairs (N = 507 individuals), aged 80 and older (mean age = 83.3 years: SD = 3.1). who remained nondemented over the course of the study. Latent growth models (LGMs) show that chronological age and time to death are consistent predictors of decline in measures of memory, reasoning, speed, and verbal abilities. Multivariate LGM analysis resulted in weak and often negative correlations among rates of change between individuals within twin pairs, indicating greater differential change within twin pairs than occurs on average across twin pairs. These findings highlight several challenges for estimating genetic sources of variance in the context of compromised health and mortality-related change.

Adult age differences in multiple cognitive functions: differentiation, dedifferentiation, or process-specific change?

Adult age differences in covariance structures of latent variables of vocabulary, list recall, speed, working memory, and text recall, were analyzed to test hypotheses of structural changes with age. There were baseline data from 613 men and women aged 30-97, data from a second wave of testing from 322 people, and complete longitudinal data from 289 people. There were age differences in the size but not configuration of factor loadings cross-sectionally but not longitudinally. There were no changes in factor standard deviations or covariances. Findings did not support models of dedifferentiation with age.

Response selection and execution in patients with Parkinson's disease

Different studies report diverse, sometimes conflicting findings, regarding the ability of Parkinson's disease (PD) patients to benefit from advanced cuing in choice reaction time (RT). Thus, conclusions about the changed state of underlying processes such as set formation, motor programming and motor initiation are not certain. In the present study, visual choice RT testing that utilized brief (100 ms) color signals (red/blue), was followed by auditory choice reaction time (CRT) testing with brief (100 ms) low/high pitch sound stimuli. Response consisted of either index or middle finger flexion. The signals were then combined so that the color stimuli cued the sound stimuli with an 800-ms interstimuli interval. Cuing validity was reduced from 100% during training to 76% during final testing. In addition, the same sound stimuli were presented randomly, without visual cuing, in which case response should have been suppressed. Tested subjects include 19 moderate PD patients, 21 elderly controls and 20 young controls. The patients did not differ from the controls in error rate but were slower to respond, except under 100% congruent cuing, indicating that their extended RT in CRT results from slowed stimulus-response linking and not from impaired motor initiation/execution. In the final condition patients showed no perseverance and demonstrated normal speed of set shifting in incongruent trials.