Cognitive performance and mortality among patients receiving autologous hematopoietic stem cell transplant

OBJECTIVES

Patients undergoing autologous hematopoietic stem cell transplant (HCT) are at risk for death and remain understudied relative to those undergoing allogeneic HCT. Cognitive functioning may be a useful indicator of mortality risk. We examined cognition among patients who underwent autologous HCT and its relationship to mortality.

METHODS

Participants (N = 51; 11 patients deceased) completed tasks of processing speed, working memory, executive-mediated learning, and visual recall using the computerized CogState battery prior to HCT, 30 days post-autologous HCT, and 100 days post-autologous HCT.

RESULTS

Slower processing speed (HR = 3.00) and more errors on an executive-mediated visual learning task (HR = 2.78) prior to HCT were associated with an increased risk of death following HCT. Our sample size limited longitudinal analyses of whether cognitive change predicted survival, however descriptive cognitive data of the deceased versus living patient's performances over time suggested different patterns of performance across groups.

CONCLUSIONS

Pre-HCT cognition may have utility as an indicator of mortality risk following autologous HCT. More research is needed to examine whether cognitive changes after HCT could also predict mortality.

Trajectories of Pain in Very Old Age: The Role of Eudaimonic Wellbeing and Personality

Pain is common in very old age and in the last years prior to death. However, little is known regarding longitudinal trajectories of pain in very old age and at the end of life. Moreover, whereas medical and morbidity-related factors contributing to pain are established, the role of psychosocial factors, such as eudaimonic wellbeing or personality as potential determinants of late-life pain trajectories has so far not been sufficiently investigated. We used data from the LateLine project. The sample consisted of n = 118 very old adults (M = 90.5 years, SD = 2.8 years) who were living alone at baseline and who had died between 2009 and 2021. They took part in up to 16 measurement occasions (M = 5.2, SD = 4.7, range 1–16) within an observational interval of 7 years. Assessment of pain was based on the SF-36 bodily pain subscale. Key indicators of eudaimonic wellbeing (autonomy, environmental mastery, and purpose in life) as well two of the Big Five personality traits (neuroticism and extraversion) were included as predictors. We controlled in all analyses for gender, education, subjective health, and depressive symptoms. Contrasting pain trajectories over chronological age (time since birth) vs. time to death, a time-to-death-related model resulted in a better model fit and accounted for a larger amount of pain variability than the age-related model. Mean-level change in pain, both over age and time to death, was not significant, but there was substantial interindividual variability in intraindividual trajectories. Age-related change in pain was significantly predicted by autonomy and neuroticism, with increasing pain among those who had lower initial autonomy scores and higher initial neuroticism scores. With regard to time-to-death-related trajectories of pain, higher purpose in life as well as lower extraversion at baseline predicted less increase or even steeper decrease in pain with approaching death. Our findings suggest that, despite overall mean-level stability in pain both over age and time to death, there is a substantial proportion of individuals who reveal deterioration in pain over time. Regarding the role of psychosocial predictors, personality traits and eudaimonic wellbeing are related with late-life pain trajectories both over age and time-to-death.

Cognition-Mortality Associations Are More Pronounced When Estimated Jointly in Longitudinal and Time-to-Event Models

With aging populations worldwide, there is growing interest in links between cognitive decline and elevated mortality risk—and, by extension, analytic approaches to further clarify these associations. Toward this end, some researchers have compared cognitive trajectories of survivors vs. decedents while others have examined longitudinal changes in cognition as predictive of mortality risk. A two-stage modeling framework is typically used in this latter approach; however, several recent studies have used joint longitudinal-survival modeling (i.e., estimating longitudinal change in cognition conditionally on mortality risk, and vice versa). Methodological differences inherent to these approaches may influence estimates of cognitive decline and cognition-mortality associations. These effects may vary across cognitive domains insofar as changes in broad fluid and crystallized abilities are differentially sensitive to aging and mortality risk. We compared these analytic approaches as applied to data from a large-sample, repeated-measures study of older adults (N = 5,954; ages 50–87 years at assessment; 4,453 deceased at last census). Cognitive trajectories indicated worse performance in decedents and when estimated jointly with mortality risk, but this was attenuated after adjustment for health-related covariates. Better cognitive performance predicted lower mortality risk, and, importantly, cognition-mortality associations were more pronounced when estimated in joint models. Associations between mortality risk and crystallized abilities only emerged under joint estimation. This may have important implications for cognitive reserve, which posits that knowledge and skills considered well-preserved in later life (i.e., crystallized abilities) may compensate for declines in abilities more prone to neurodegeneration, such as recall memory and problem solving. Joint longitudinal-survival models thus appear to be important (and currently underutilized) for research in cognitive epidemiology.

Decline in Memory, Visuospatial Ability, and Crystalized Cognitive Abilities in Older Adults: Normative Aging or Terminal Decline?

The aim of this study is to explore the pattern of change in multiple measures of cognitive abilities in a sample of oldest-old adults, comparing two different time metrics (chronological age and time to death) and therefore examining both underlying conceptual assumptions (age-related change and terminal decline). Moreover, the association with individual characteristics as sex, education, and dementia diagnosis was also examined. Measures of cognitive status (Mini-Mental State Examination and the Swedish Clock Test) and tests of crystallized (knowledge and synonyms), memory (verbal memory, nonverbal long-term memory, recognition and correspondence, and short-term memory), and visuospatial ability were included. The sample consisted of 671 older Swedish adult participants of the OCTO Twin Study. Linear mixed models with random coefficients were used to analyse change patterns and BIC indexes were used to compare models. Results showed that the time to death model was the best option in analyses of change in all the cognitive measures considered (except for the Information Test). A significant cognitive decline over time was found for all variables. Individuals diagnosed with dementia had lower scores at the study entrance and a faster decline. More educated individuals performed better in all the measures of cognition at study entry than those with poorer education, but no differences were found in the rate of change. Differences were found in age, sex, or time to death at baseline across the different measures. These results support the terminal decline hypothesis when compared to models assuming that cognitive changes are driven by normative aging processes.

I forgot when I lost my grip-strong associations between cognition and grip strength in level of performance and change across time in relation to impending death

An association between level of cognitive function and grip strength is well established, whereas evidence for longitudinal associations of change in the 2 functions is still unclear. We examined associations between cognition and grip strength in levels of performance and in longitudinal change in late life in a population-based sample, aged ≥80 years at baseline, followed until death. The sample consisted of 449 nondemented individuals drawn from the OCTO-Twin Study. A test battery assessing 6 cognitive domains and grip strength was administered at 5 occasions with measurements intervals of 2 years. We fitted time to death bivariate growth curve models, adjusted for age, education, and sex which resulted in associations between grip strength and cognition in both levels of performance (across all cognitive domains) and rates of change (in 4 of 6 domains). These results show that cognition and grip strength change conjointly in later life and that the association between cognition and grip strength is stronger before death than earlier in life.

Guidelines for reporting methodological challenges and evaluating potential bias in dementia research

Clinical and population research on dementia and related neurologic conditions, including Alzheimer's disease, faces several unique methodological challenges. Progress to identify preventive and therapeutic strategies rests on valid and rigorous analytic approaches, but the research literature reflects little consensus on "best practices." We present findings from a large scientific working group on research methods for clinical and population studies of dementia, which identified five categories of methodological challenges as follows: (1) attrition/sample selection, including selective survival; (2) measurement, including uncertainty in diagnostic criteria, measurement error in neuropsychological assessments, and practice or retest effects; (3) specification of longitudinal models when participants are followed for months, years, or even decades; (4) time-varying measurements; and (5) high-dimensional data. We explain why each challenge is important in dementia research and how it could compromise the translation of research findings into effective prevention or care strategies. We advance a checklist of potential sources of bias that should be routinely addressed when reporting dementia research.

A framework for studying mechanisms underlying terminal decline in well-being

Multiple facets of well-being are known to show steep end-of-life deteriorations. However, the underlying mechanisms and pathways are vague. Capitalizing on an earlier review of the existing empirical literature on terminal decline, we present a conceptual/methodological framework that can be used as a tool to structure future inquiry aimed at refining the precision and specificity of the terminal decline concept. Specifically, we propose a model of terminal decline in well-being in which within-person mean levels of, inconsistencies in, or couplings among multiple domains of functioning serve as indicators or sources of well-being. The model, based on time-varying dynamic factor analysis of intensive longitudinal data, provides for concise articulation and testing of central tenets of theories of successful aging, including hypotheses regarding shifts in goals away from some domains and towards others (e.g. secondary control). We conclude by suggesting routes for empirical research.

Gender Differences in Cognitive Performance in Old Age

Objective: To examine gender differences in level and change of cognitive performance in the oldest old while accounting for gender differences in longevity. Method: 574 individuals, aged 80 years and older, from the OCTO Twin Study. Five cognitive domains were administered at five occasions at 2-year intervals. Results: There were no cognitive differences between men and women, with the exception that men showed a steeper rate of decline in semantic memory. This effect was driven by men who had developed dementia and declined at a faster rate than women. Conclusion: Our results support previous findings showing minor to nonexisting gender differences in cognition among nondemented individuals in very old age when taking gender differences in longevity into account.

Education associated with a delayed onset of terminal decline

Background: the terminal decline hypothesis suggests an acceleration in the rate of loss of cognitive function before death. Evidence about the association of educational attainment and the onset of terminal decline is scarce.

Objective: to investigate the association of education with the onset of terminal decline in global cognitive function measured by Mini Mental State Exam (MMSE) scores.

Subjects: deceased participants of the Cambridge City over 75 Cohort Study who were interviewed at about 2, 7, 9, 13, 17 and 21 years after baseline.

Methods: regular and Tobit random change point growth models were fitted to MMSE scores to identify the onset of terminal decline and assess the effect of education on this onset.

Results: people who left school at an older age had a delayed onset of terminal decline. Thus better educated individuals experience a slightly shorter period of faster decline before death.

Conclusion: an important finding emerging from our work is that education does appear to delay the onset of terminal decline, although only by a limited amount.

Trajectories of cognitive decline following dementia onset: what accounts for variation in progression?

BACKGROUND

Delineating the natural history of dementia progression has important clinical implications, including reducing caregiver burden and targeting effective drug trials. We examined whether trajectories of cognitive change differed reliably after diagnosis, and whether diverse predictors of such differences (demographic, psychological, biological, genetic, social) could be identified.

METHODS

Cognitive change was examined for incident dementia cases (mild: n = 156; moderate: n = 77; severe: n = 73) and controls (n = 249) from the Kungsholmen Project, a community-based study of adults 75 years and older.

RESULTS

For those with dementia, total variance attributed to between-person differences in cognitive decline was modest and linked to but a single predictor (history of cardiovascular disease). Although less variance in cognitive decline was observed for the similarly aged controls, numerous significant predictors of these differences were identified.

CONCLUSION

The neurodegenerative process underlying dementia overshadows formerly significant predictors of cognitive change.

Changes in depressive symptoms in the context of disablement processes: role of demographic characteristics, cognitive function, health, and social support

OBJECTIVES

Gerontological research suggests that depressive symptoms show antecedent and consequent relations with late-life disability. Less is known, however, about how depressive symptoms change with the progression of disability-related processes and what factors moderate such changes.

METHODS

We applied multiphase growth models to longitudinal data pooled across 4 Swedish studies of very old age (N = 779, M age = 86 years at disability onset, 64% women) to describe change in depressive symptoms prior to disability onset, at or around disability onset (the measurement wave at which assistance in personal activities of daily living was first recorded), and postdisability onset.

RESULTS

Results indicate that, on average, depressive symptoms slightly increase with approaching disability, increase at onset, and decline in the postdisability phase. Age, study membership, being a woman, and multimorbidity were related to depressive symptoms, but social support emerged as the most powerful predictor of level and change in depressive symptoms.

DISCUSSION

Our findings are consistent with conceptual notions implicating disability-related factors as key contributors to late-life change and suggest that contextual and psychosocial factors play a pivotal role for how well people adapt to late-life challenges.

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.

Toward an integrative science of life-span development and aging

The study of aging demands an integrative life-span developmental framework, involving interdisciplinary collaborations and multiple methodological approaches for understanding how and why individuals change, in both normative and idiosyncratic ways. We highlight and summarize some of the issues encountered when conducting integrative research for understanding aging-related change, including, the integration of results across different levels of analysis; the integration of theory, design, and analysis; and the synthesis of results across studies of aging. We emphasize the necessity of longitudinal designs for understanding development and aging and discuss methodological issues that should be considered for achieving reproducible research on within-person processes. It will be important that current and future studies permit opportunities for quantitative comparison across populations given the extent to which historical shifts and cultural differences influence life-span processes and aging-related outcomes.

Aging, Disablement, and Dying: Using Time-as-Process and Time-as-Resources Metrics to Chart Late-Life Change

Time is a vehicle that can be used to represent aging-related processes and to index the amount of aging-related resources or burdens individuals have accumulated. Using data on cognitive (memory) performance from two Swedish studies of the elderly (OCTO and OCTO-TWIN), we illustrate how time-as-process and time-as-resources/burdens time metrics can be articulated and incorporated within a growth curve modeling framework. Our results highlight the possibilities for representing the contributions of primary, secondary, and tertiary aspects of aging to late-life changes in cognitive and other domains of functioning.

Application of a joint multivariate longitudinal-survival analysis to examine the terminal decline hypothesis in the Swiss Interdisciplinary Longitudinal Study on the Oldest Old

In this work I aim at extending current knowledge on the terminal decline hypothesis by applying a joint multivariate longitudinal-survival analysis to the cognitive data of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old. (In that study, 529 individuals between 79 and 85 years of age at study inception were assessed up to five times on a task of perceptual speed and one of verbal fluency.) I simultaneously estimated a multivariate, multilevel longitudinal model and a Weibull survival model to test whether individual performance and change in speed and fluency predict survival, controlling for retest effects, initial age, gender, overall health, socioeconomic status, and sensory functioning. Results revealed that age and performance level in fluency predicted survival, whereas level in speed and change in both cognitive variables did not. I discuss the relevance of fluency tasks in predicting mortality.

Association between mortality and cognitive change over 7 years in a large representative sample of UK residents

OBJECTIVE

To examine the association between change in reaction time and cognitive performance over 7 years and the risk of death from all causes and some specific causes after controlling for known risk factors.

METHODS

The sample comprised members of the Health and Lifestyle Survey (HALS) of community-dwelling adults in England, Scotland, and Wales. Baseline testing (HALS1), involving 9003 people, took place in 1985 and 1986. Sociodemographic, lifestyle, health, and physiological information was collected. Cognitive functioning was measured using tests of simple and choice reaction time, a short memory test, and a test of visual-spatial reasoning. Follow-up testing (HALS2) took place in 1991 and 1992, when 5352 members of the study were administered the same questionnaires, physiological examinations, and cognitive tests. The sample has been followed for mortality up to June 2005.

RESULTS

After controlling for age, gender, and the relevant baseline cognitive test scores, greater declines between HALS1 and HALS2 on simple reaction time mean and variability, choice reaction time mean and variability, memory and visual-spatial reasoning were associated with significantly increased risks of death from all causes, all cardiovascular diseases (CVDs), coronary heart disease (CHD), stroke, and respiratory disease. These associations were only slightly attenuated after adjusting for occupational social class, educational, smoking, alcohol consumption, physical activity, body mass index, blood pressure, and lung function.

CONCLUSIONS

Decline in performance of reaction times and simple cognitive tasks across a 7-year period was associated with an increased risk of death from all causes, all CVDs, CHD, stroke, and respiratory disease up to 13 years later, even after adjustment for known risk factors.