The terminal drop hypothesis: fact or artifact?

Predictors of Mortality in 433 Nonagenarians Inside the Mugello Study: A 10 Years Follow-Up Study

OBJECTIVE

to identify the predictors of mortality in a cohort of nonagenarians inside the "Mugello study" after 10 years follow-up.

METHODS

Information on sociodemographic data, cognitive and functional status, lifestyle, medical history, and drug use was collected from 433 non-selected participants aged 90-99 years, living in the Mugello area (Italy). Participants were followed over 10 years and their dates of death were retrieved from the municipal registers. Cox regression analysis was used to determine significant potential prognostic factors.

RESULTS

The mortality rate was 96.5%. Cox proportional hazards analysis showed that a lower cognitive status was significantly associated with higher mortality as well as a poorer functional status, a higher comorbidity, and a higher number of drugs consumption.

DISCUSSION

Impaired cognitive function, loss of functional independence, higher comorbidity, and higher drugs intake were the stronger predictors of mortality.

Proportion of cognitive loss attributable to terminal decline

OBJECTIVE

To estimate the proportion of late-life cognitive loss attributable to impending death.

METHODS

Older persons (n = 1,071) in a longitudinal cohort study without dementia at enrollment underwent annual cognitive assessments (mean 10.6 years, SD 4.6, range 4-24) prior to death. We estimated the onset of terminal acceleration in cognitive decline and rates of decline before and after this point in change point models that allowed calculation of the percent of cognitive loss attributable to terminal decline. Outcomes were composite measures of global and specific cognitive functions. We also estimated dementia and mild cognitive impairment (MCI) incidence before and during the terminal period.

RESULTS

A mean of 3.7 years before death (95% credible interval [CI] -3.8 to -3.5), the rate of global cognitive decline accelerated to -0.313 unit per year (95% CI -0.337 to -0.290), a more than 7-fold increase indicative of terminal decline. The mean global cognitive score dropped 0.377 unit (SD 0.516) assuming no terminal decline and 1.192 units (SD 1.080) with terminal decline. As a result, 71% (95% bootstrapped CI 0.70, 0.73) of overall global cognitive loss was terminal. In subsequent analyses, terminal decline accounted for 70% of episodic memory loss, 65% of semantic memory loss, 57% of working memory loss, 52% of perceptual speed loss, and 53% of visuospatial loss. MCI incidence in the preterminal and terminal periods was similar, but dementia incidence was more than 6-fold higher in the terminal period than preterminal.

CONCLUSION

Most late-life cognitive loss is driven by terminal decline.

When does cognitive decline begin? A systematic review of change point studies on accelerated decline in cognitive and neurological outcomes preceding mild cognitive impairment, dementia, and death

Older adults who ultimately develop dementia experience accelerated cognitive decline long before diagnosis. A similar acceleration in cognitive decline occurs in the years before death as well. To evaluate preclinical and terminal cognitive decline, past researchers have incorporated change points in their analyses of longitudinal data, identifying point estimates of how many years prior to diagnosis or death that decline begins to accelerate. The current systematic review aimed to summarize the published literature on preclinical and terminal change points in relation to mild cognitive impairment (MCI), dementia, and death, identifying the order in which cognitive and neurological outcomes decline and factors that modify the onset and rate of decline. A systematic search protocol yielded 35 studies, describing 16 longitudinal cohorts, modeling change points for cognitive and neurological outcomes preceding MCI, dementia, or death. Change points for cognitive abilities ranged from 3-7 years prior to MCI diagnosis, 1-11 years prior to dementia diagnosis, and 3-15 years before death. No sequence of decline was observed preceding MCI or death, but the following sequence was tentatively accepted for Alzheimer's disease: verbal memory, visuospatial ability, executive functions and fluency, and last, verbal IQ. Some of the modifiers of the onset and rate of decline examined by previous researchers included gender, education, genetics, neuropathology, and personality. Change point analyses evidence accelerated decline preceding MCI, dementia, and death, but moderators of the onset and rate of decline remain ambiguous due to between-study modeling differences, and coordinated analyses may improve comparability across future studies. (PsycINFO Database Record

Systolic Blood Pressure Trajectory, Frailty, and All-Cause Mortality >80 Years of Age: Cohort Study Using Electronic Health Records

BACKGROUND

Clinical trials show benefit from lowering systolic blood pressure (SBP) in people ≥80 years of age, but nonrandomized epidemiological studies suggest lower SBP may be associated with higher mortality. This study aimed to evaluate associations of SBP with all-cause mortality by frailty category >80 years of age and to evaluate SBP trajectories before death.

METHODS

A population-based cohort study was conducted using electronic health records of 144 403 participants ≥80 years of age registered with family practices in the United Kingdom from 2001 to 2014. Participants were followed for ≤5 years. Clinical records of SBP were analyzed. Frailty status was classified using the e-Frailty Index into the categories of fit, mild, moderate, and severe. All-cause mortality was evaluated by frailty status and mean SBP in Cox proportional-hazards models. SBP trajectories were evaluated using person months as observations, with mean SBP and antihypertensive treatment status estimated for each person month. Fractional polynomial models were used to estimate SBP trajectories over 5 years before death.

RESULTS

During follow-up, 51 808 deaths occurred. Mortality rates increased with frailty level and were greatest at SBP <110 mm Hg. In fit women, mortality was 7.7 per 100 person years at SBP 120 to 139 mm Hg, 15.2 at SBP 110 to 119 mm Hg, and 22.7 at SBP <110 mm Hg. For women with severe frailty, rates were 16.8, 25.2, and 39.6, respectively. SBP trajectories showed an accelerated decline in the last 2 years of life. The relative odds of SBP <120 mm Hg were higher in the last 3 months of life than 5 years previously in both treated (odds ratio, 6.06; 95% confidence interval, 5.40-6.81) and untreated (odds ratio, 6.31; 95% confidence interval, 5.30-7.52) patients. There was no evidence of intensification of antihypertensive therapy in the final 2 years of life.

CONCLUSIONS

A terminal decline of SBP in the final 2 years of life suggests that nonrandomized epidemiological associations of low SBP with higher mortality may be accounted for by reverse causation if participants with lower blood pressure values are closer, on average, to the end of life.

Age and Distance to Death in the Seattle Longitudinal Study

A series of hierarchical regression models was used to determine if time to death was a significant independent variable for level and seven-year change in intellectual performance for 1,214 community-dwelling adults. Distance to death explained a significant amount of the variance of intellectual performance at individuals’last measurement but not of the decline in performance after controlling for age, education, gender, and survivorship. The inclusion of time to death improved the proportion of unique variance explained by about 1% to 3% and between 4% and 10.4% of the total variance explained. Decedents had lower levels of verbal meaning, spatial ability, reasoning ability, and psychomotor speed at last measurements and greater amounts of seven-year decline on verbal meaning and psychomotor speed. The inclusion of distance to death may help improve the explanation of variability in performance associated with increased age.

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.

Investigating terminal decline: results from a UK population-based study of aging

The terminal decline hypothesis states that in the proximity of death, an individual's decline in cognitive abilities accelerates. We aimed at estimating the onset of faster rate of decline in global cognition using Mini Mental State Examination (MMSE) scores from participants of the Cambridge City over 75 Cohort Study (CC75C), a U.K. population-based longitudinal study of aging where almost all participants have died. The random change point model fitted to MMSE scores structured as a function of distance to death allowed us to identify a potentially different onset of change in rate of decline before death for each individual in the sample. Differences in rate of change before and after the onset of change in rate of decline by sociodemographic variables were investigated. On average, the onset of a faster rate of change occurred about 7.7 years before death and varied across individuals. Our results show that most individuals experience a period of slight decline followed by a much sharper decline. Education, age at death, and cognitive impairment at study entry were identified as modifiers of rate of change before and after change in rate of decline. Gender differences were found in rate of decline in the final stages of life. Our study suggests that terminal decline is a heterogeneous process, with its onset varying between individuals.

Cohort differences in cognitive aging and terminal decline in the Seattle Longitudinal Study

Life span researchers have long been interested in how and why fundamental aspects of human ontogeny differ between cohorts of people who have lived through different historical epochs. When examined at the same age, later born cohorts are often cognitively and physically fitter than earlier born cohorts. Less is known, however, about cohort differences in the rate of cognitive aging and if, at the very end of life, pervasive mortality-related processes overshadow and minimize cohort differences. We used data on 5 primary mental abilities from the Seattle Longitudinal Study (Schaie, 2005) to compare both age-related and mortality-related changes between earlier born cohorts (1886-1913) and later born cohorts (1914-1948). Our models covary for several individual and cohort differences in central indicators of life expectancy, education, health, and gender. Age-related growth models corroborate and extend earlier findings by documenting level differences at age 70 of up to 0.50 SD and less steep rates of cognitive aging on all abilities between 50 and 80 years of age favoring the later born cohort. In contrast, mortality-related models provide limited support for positive cohort differences. The later born cohort showed steeper mortality-related declines. We discuss possible reasons why often reported positive secular trends in age-related processes may not generalize to the vulnerable segment of the population that is close to death and suggest routes for further inquiry.

An evaluation of analytical approaches for understanding change in cognition in the context of aging and health

OBJECTIVES

In this article, we discuss the importance of studying the relationship between health and cognitive function, and some of the methods with which this relationship has been studied.

METHODS

We consider the challenges involved, in particular operationalization of the health construct and causal inference in the context of observational data. We contrast the approaches taken, and review the questions addressed: whether health and cognition are associated, whether changes in health are associated with changes in cognition, and the degree of interdependency among their respective trajectories.

RESULTS

A variety of approaches for understanding the association between cognition and health in aging individuals have been used. Much of the literature on cognitive change and health has relied on methods that are based at least in part on the reorganization of between-person differences (e.g., cross-lag analysis) rather than relying more fully on analysis of within-person change and joint analysis of individual differences in within-person change in cognition and health.

DISCUSSION

We make the case for focusing on the interdependency between within-person changes in health and cognition and suggest methods that would support this.

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.

Joint modeling of missing data due to non-participation and death in longitudinal aging studies

Specific age-related hypotheses are tested in population-based longitudinal studies. At specific time intervals, both the outcomes of interest and the time-varying covariates are measured. When participants are approached for follow-up, some participants do not provide data. Investigations may show that many have died before the time of follow-up whereas others refused to participate. Some of these non-participants do not provide data at later follow-ups. Few statistical methods for missing data distinguish between 'non-participation' and 'death' among study participants. The augmented inverse probability-weighted estimators are most commonly used in marginal structure models when data are missing at random. Treating non-participation and death as the same, however, may lead to biased estimates and invalid inferences. To overcome this limitation, a multiple inverse probability-weighted approach is presented to account for two types of missing data, non-participation and death, when using a marginal mean model. Under certain conditions, the multiple weighted estimators are consistent and asymptotically normal. Simulation studies will be used to study the finite sample efficiency of the multiple weighted estimators. The proposed method will be applied to study the risk factors associated with the cognitive decline among the aging adults, using data from the Chicago Health and Aging Project (CHAP).

Longitudinal Data with Follow-up Truncated by Death: Match the Analysis Method to Research Aims

Diverse analysis approaches have been proposed to distinguish data missing due to death from nonresponse, and to summarize trajectories of longitudinal data truncated by death. We demonstrate how these analysis approaches arise from factorizations of the distribution of longitudinal data and survival information. Models are illustrated using cognitive functioning data for older adults. For unconditional models, deaths do not occur, deaths are independent of the longitudinal response, or the unconditional longitudinal response is averaged over the survival distribution. Unconditional models, such as random effects models fit to unbalanced data, may implicitly impute data beyond the time of death. Fully conditional models stratify the longitudinal response trajectory by time of death. Fully conditional models are effective for describing individual trajectories, in terms of either aging (age, or years from baseline) or dying (years from death). Causal models (principal stratification) as currently applied are fully conditional models, since group differences at one timepoint are described for a cohort that will survive past a later timepoint. Partly conditional models summarize the longitudinal response in the dynamic cohort of survivors. Partly conditional models are serial cross-sectional snapshots of the response, reflecting the average response in survivors at a given timepoint rather than individual trajectories. Joint models of survival and longitudinal response describe the evolving health status of the entire cohort. Researchers using longitudinal data should consider which method of accommodating deaths is consistent with research aims, and use analysis methods accordingly.

Differential Psychological Ageing: Profiles of the Old and Very Old

Theoretical positions which argue for age-related and individual variation in profiles of psychological functioning and patterns of predictive relationships are reviewed in the context of the three domains investigated by the Psychology Unit of the Berlin Aging Study (BASE): intelligence and cognition, self and personality, and social relationships. To illustrate the potential of BASE, we report initial data for a small set of variables from these three psychological domains for the first wave of study participants (N = 360, age range 70 to 103 years). Our analyses of these data were targeted toward three key questions about differential psychological ageing: namely, the extent of age/cohort-related differences and individual variation within each domain, possible age differences in the structural relationships between the three domains, and subgroup variations in cross-domain profiles of functioning. Within domains, individual differences in general were very large. Chronological age accounted for a sizeable proportion of the variance only in the domain of cognitive performance. The structural relationships between the domains of psychological functioning were similar for the old and very old age groups and reflected much domain independence. Examination of subgroup variations in cross-domain profiles of functioning revealed ten subgroups. All subgroups showed an uneven, that is, age-selective group membership: five subgroups included more of the very old, two more of the old, and three were age-specific. Preliminary explorations of these subgroups suggested substantial links to selected health-related variables, supporting proposals for multi-disciplinary research into differential ageing.

Life satisfaction shows terminal decline in old age: longitudinal evidence from the German Socio-Economic Panel Study (SOEP)

Longitudinal data spanning 22 years, obtained from deceased participants of the German Socio-Economic Panel Study (SOEP; N = 1,637; 70- to 100-year-olds), were used to examine if and how life satisfaction exhibits terminal decline at the end of life. Changes in life satisfaction were more strongly associated with distance to death than with distance from birth (chronological age). Multiphase growth models were used to identify a transition point about 4 years prior to death where the prototypical rate of decline in life satisfaction tripled from -0.64 to -1.94 T-score units per year. Further individual-level analyses suggest that individuals dying at older ages spend more years in the terminal periods of life satisfaction decline than individuals dying at earlier ages. Overall, the evidence suggests that late-life changes in aspects of well-being are driven by mortality-related mechanisms and characterized by terminal decline.

Decline in life satisfaction in old age: longitudinal evidence for links to distance-to-death

Using 12-year longitudinal data from deceased participants of the Berlin Aging Study (N = 414; age 70-103 years, at first occasion; M = 87 years, SD = 8.13), the authors examined whether and how old and very old individuals exhibit terminal decline in reported life satisfaction at the end of life. Relative to age-related decline, mortality-related decline (i.e., distance-to-death) accounted for more variance in interindividual differences in life satisfaction change and revealed steeper average rates of decline, by a factor of 2. By applying change-point growth models, the authors identified a point, about 4 years before death, at which decline showed a two-fold increase in steepness relative to the preterminal phase. For the oldest old (85+ years), a threefold increase was observed. Established mortality predictors, including sex, comorbidities, dementia, and cognition, accounted for only small portions of interindividual differences in mortality-related change in life satisfaction. The authors conclude that late-life changes in subjective well-being are related to mechanisms predicting death and suggest routes for further inquiry.

Neuropsychological prediction of attrition due to death

In aging research, attrition bias produces underestimates of cognitive decline and limits the interpretation of cognitive change. Using data from the Canadian Study of Health and Aging, we identified neuropsychological predictors of death among not cognitively impaired (NCI) and cognitively impaired, not-demented (CIND) persons. For those with NCI, two neuropsychological measures significantly predicted attrition, over and above age, in the short term, while age was the best long-term predictor. The absence of neuropsychological predictors for the CIND group may reflect the group's etiological heterogeneity. In future research, the use of a more homogeneous subset of CIND may yield additional predictors.

Population Inference with Mortality and Attrition in Longitudinal Studies on Aging: A Two-Stage Multiple Imputation Method

A major challenge for inference regarding aging-related change in longitudinal studies is that of study attrition and population mortality. Inferences in longitudinal studies can account for attrition and mortality-related change as distinct processes, but this is made difficult when follow-up of all individuals (i.e., age at death) is not complete. This is a common problem because most longitudinal studies of aging either have incomplete follow-up or are still collecting data on subsequent outcomes, including time of death. A statistical approach is suggested for including time-to-death as a predictor in models with incomplete follow-up using a two-stage multiple-imputation procedure. An empirical example using data from the OCTO-Twin study is presented that shows the utility of his procedure for making inferences conditional on mortality when mortality data are incomplete.

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.

Prediction of survival in 70-year olds

The purpose of this study was to find predictors of 10-year survival among 70-year olds and to show that there might be more than one good set of predictors. All variables found to be significantly related to survival in univariate tests (predictors) are given a risk value (0 = no risk, 1 = risk), and classified into high-order domains. The number of domains containing predictors with risk values are then counted, giving the individual a certain risk index. The method was applied on data from the longitudinal population study of 70-year-old people in Gothenburg, Sweden, the H70-study. In a random sample of 474 men and 562 women predictors for survival over a 10-year period, from the age of 70, were selected for men and women, respectively. The predictors were classified into seven domains: socio-economic status, life style, social networks, need of help, biomarkers of ageing, physical health and cognitive function. The analysis revealed a consistent pattern in which survival was related to the number of risk domains. In the no-risk sub-sample 12.5% of the men were deceased after 10 years, in the sub-sample with five or more risk domains involved 78.0% were deceased. The corresponding figures for women were 10.0% and 60.0%. The results show that it is possible to find variables that can predict survival. However, there is not only one set of good predictors. As an alternative to use of specific variables as predictors the presumptive predictors can be grouped into a few main domains and good predictions be made on the basis of these domains.

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.

The Aberdeen Children of the 1950s cohort study: background, methods and follow-up information on a new resource for the study of life course and intergenerational influences on health

In this paper we introduce and describe in detail an addition to the UK's population-based resources for the investigation of biological and social influences on health across the life course and between generations: the Aberdeen Children of the 1950s study. We also provide an account of postwar Aberdeen when study members were growing up, report on findings of analyses of data from the original survey on which this study is based and its follow-up, assess the strengths and limitations of the study, and outline current and future research directions. This cohort comprises individuals born in Aberdeen, Scotland (UK) between 1950 and 1956, and is derived from 15 thousand subjects who took part in the Aberdeen Child Development Survey, a cross-sectional study of 'mental subnormality' (learning disability) in a population of all children who were attending Aberdeen primary schools in December 1962. Data collection included information on birthweight, gestational age, childhood height and weight, tests of cognition and behavioural disorder, and a range of multilevel socio-economic indicators. In 1998 we began the process of revitalising this cohort (now termed the Aberdeen Children of the 1950s study). We have been successful in ascertaining the current vital status and whereabouts of 98.5% of a target population of 12 150 subjects (6276 males, 5874 females) with full baseline data. The large majority (81%) of study participants still reside in Scotland and many (73%) have remained in the Grampian region which incorporates Aberdeen. At the present time, a total of almost 500 subjects are known to have died. Linkages to hospital admissions and other health endpoints captured through the Scottish Morbidity Records system have been completed. This includes an intergenerational linkage to approximately eight thousand deliveries in Scotland occurring to female members of the study population. A postal questionnaire to all traced surviving cohort members has also been distributed.

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

Six different cognitive tests and the Heck Depression Inventory (BDI) were given to 3,572 active community residents aged 49 to 93 years. Causes of death were ascertained for 443 who died between 36 and 3,903 days later. Subsequent survival predicted test scores during the 3,903 days and independently during Days 36 to 1,826 and Days 1,827 to 3,903. Scores on the BDI and cumulative verbal learning and vocabulary tests predicted mortality after demographics and performance on other cognitive tests had been considered. Predictors were similar for deaths from heart disease, malignancies, and other causes. A new finding that cognitive tests did not predict survival duration within the sample of deceased explains previous findings of greater terminal decline in performance for young than for elderly adults.

Terminal change in cognitive function: an updated review of longitudinal studies

We provide an update to Siegler's (1975) review of the terminal change literature. Articles identified through MEDLINE, CANCERLIT, PUBMED, and PSYCINFO from 1975 to 2000 were examined. Lower levels of cognitive function are related to increased risk of mortality; however, the relationship between rate of cognitive change and mortality is less clear. Although there has been an increase in the number of studies since our last review, prior studies have been limited by a lack of medical data, consideration of dementia, small sample sizes, and poor cognitive measures. The emphasis on Alzheimer's disease and the growth of epidemiology of aging in the past 25 years have provided well-characterized population studies with serial cognitive measures that provide an opportunity to test the theory of terminal change.

Survival effects in cognitive function, cognitive style, and sociodemographic variables in the Seattle Longitudinal Study

Survival effects in cognitive performance were examined in the Seattle Longitudinal Study (SLS) for a sample of 605 individuals who subsequently died (decedents) (n = 343 males; n = 262 females; M = 73.73 years of age) and a control group of 613 survivors (n = 299 males; n = 314 females; M = 71.91 years of age). A sample of survivors of similar age and have a similar level of education as the decedents was selected. Differences in cognitive functioning and cognitive style in level and change over time between decedents and survivors were studied. Decedents had lower levels of crystallized abilities (Verbal Meaning and Numerical Ability), visualization abilities (Spatial Orientation), verbal memory (Delayed Word Recall), perceptual speed (Identical Pictures), and Psychomotor Speed at last measurement. Decedents also had greater declines on Psychomotor Speed and Verbal Meaning at 7 and 14 years before the conclusion of the study. Survival effects were found to be ability-specific, appeared primarily in older adults, were more evident for males, and were observed up to 14 years before last measurement for specific abilities. Age-related changes in fluid ability appeared to be normative, whereas changes in crystallized abilities and perceptual speed may signify impending mortality.

The Swedish Centenarian Study: a multidisciplinary study of five consecutive cohorts at the age of 100

Centenarians born 1887-91, who lived in southern Sweden were asked to participate in this multidisciplinary study (N = 164). Of the survivors (N = 143), 70 percent agreed (N = 100). The purpose was to describe the population from physical, social, and psychological points of view; to characterize centenarians with various health conditions and diverse degrees of autonomy and life satisfaction; and to identify factors at 100 years that predict future survival.

RESULTS

Eighty-two percent were women, 25 percent lived in their own home, 37 percent in old age homes, and 38 percent in nursing homes. Socioeconomic status showed a similar distribution compared to nationally representative data. Fifty-two percent managed activities of daily living with or without minor assistance. The incidence of severe diseases was low. In 39 percent a disorder of the circulatory system was found. Thirty-nine percent (women) and 11 percent (men) had had at least one hip fracture. Twenty percent had good hearing and good vision. Twenty-seven percent were demented according to DSM III-R criteria. Means on cognitive tests (word-list, digit-span, learning, and memory) were lower compared to seventy to eighty year old groups. The variation in performance was extremely widespread. Personality profiles (MMPI) indicated that the centenarians were more responsible, capable, easygoing and less prone to anxiety than the population in general. Extensive neuropathological investigation revealed no major diseases or large lesions but mild through multiple changes. RESULTS suggest that centenarians are a special group genetically. A causal structure model emphasized body constitution, marital status, cognition and blood pressure as particularly important determinants for survival after 100 years.

Cognitive changes in very old persons with dementia: the influence of demographic, psychometric, and biological variables

Longitudinal changes in global cognitive functioning, indexed by the Mini-Mental State Examination (MMSE), in subjects with dementia (Alzheimer's disease and vascular dementia) were examined. The roles of several demographic, psychometric, and biological indices in predicting cognitive deterioration were also examined. The sample consisted of 36 very old (M age at entry = 83.0 years, range = 75-95) adults with dementia from a community-based study. Subjects were tested on two occasions separated by approximately 2.5 years. Results indicated significant longitudinal decline in MMSE scores over the retest interval; the average decline was estimated as 2.43 (SD = 1.81) points per year. Several factors were associated with cognitive deterioration. Higher initial MMSE scores were associated with greater deterioration, whereas superior forward digit span and Block Design at entry were associated with attenuated decline, once differences in baseline severity were accounted for. By contrast, a variety of other putatively important variables exhibited no relationship to decline, including age, gender, education, onset age, dementia type, backward digit span, as well as a number of biological parameters (e.g., vitamin B12, folic acid). The results suggest that although the magnitude of cognitive deterioration in dementia is highly variable, several indicators may be useful predictors of future changes in cognitive functioning.

Aging and cognition: methodological differences in outcome

A series of longitudinal and cross sectional studies, collected as part of the Seattle Study, were reanalyzed. A longitudinal sequential analysis (N = 232), wherein subjects were measured every seven years for four time periods, was completed on the Primary Mental Abilities test. Cohort differences were at least as strong as age differences; cohorts were generally relatively stable over the measured periods, showing little cognitive decline. A cross-sectional sequential analysis (N = 2813) was completed for the same time periods; decline with age was more evident than with the longitudinal sequential analysis. A cross-sectional analysis for the fourth time period (N = 611) showed the most marked decline of all. Interpretation of outcome was highly dependent on the analysis used.

Neuropsychological test performance, cognitive functioning, blood pressure, and age: the Framingham Heart Study

Interactions of three indices of blood pressure (systolic blood pressure, diastolic blood pressure, and chronicity of hypertension) and age-cohort membership were examined for a sample of 1,695 stroke-free participants of the Framingham Heart Study, ages 55-88 years. Blood pressure level and chronicity of hypertension were assessed over five biennial examinations performed between 1956 and 1964, a time when few hypertensives were being treated, and were related to neuropsychological tests administered between 1976 and 1978. Multiple linear regression methods were used to examine Age x Blood Pressure (or Chronicity of Hypertension) interactions in alternative analyses involving three age groups (55-64 years, 65-74 years, and 75-88 years) and age as a continuously distributed variable (age in years). Interactions were either statistically nonsignificant or trivial with respect to magnitude of effect. This was true when interaction terms (Age x Blood Pressure Level or Age x Chronicity of Hypertension) were controlled for blood pressure, age, education, occupation, cigarette smoking, alcohol consumption, gender, and antihypertensive treatment. The Age x Blood Pressure model as it pertains to older adults was not supported, but independent associations (with all covariables controlled) between the indices of blood pressure and cognitive functioning were statistically significant.

Cognitive functioning and survival in psychogeriatric patients

The relationship between cognitive functioning and survival was studied among 92 people referred to a psychogeriatric assessment unit. A follow-up 4-5 years later showed that the nonsurvivors initially had lower scores on the Mini-Mental State Examination (MMSE) than the survivors. The differences were greatest among individuals with nondementia diagnosis. Survival curves showed that about 50% of those who scored less than or equal to 19 on MMSE had died within 2 years but more than 60% of those who scored greater than or equal to 20 were still alive 4-5 years after the initial assessment.

Some determinants of attrition in prospective studies on aging

Demographic measures, psychosocial variables, and objective and subjective measures of physical impairment were assessed in elderly men twice at intervals of 12 to 18 months. Canonical discriminant function analysis of the relationship between these predictor variables on the first testing and whether participants (a) returned for retesting, (b) did not return because of apparent disinterest, or (c) did not return because of illness or death, revealed two significant canonical variates. The first, characterized by decreased mental and physical capacity, discriminated between the deceased/ill group and the other two groups. The second was characterized by decreased social interaction and life satisfaction, and increased life events, and distinguished between the disinterested group and the other two groups. However, both groups that failed to return for retesting showed evidence of impaired physical health and a general disengagement from social and personal activities, compared to the retested group.

The Kendrick Battery: sensitivity to survival effects

In an effort to establish the sensitivity of the Kendrick Battery (KB) to mortality effects among institutionalized aged, the residualized pre-death KB scores (Digit Copying, Object Learning Subtests), as well as measures of affect (Zung Depression), and organicity (Luria Pathognomic Scale, Orientation Test) were compared in a sample of fifty-three elderly persons (M age = 82.7, SD = 7.76). Forty-two were female, eleven were male. Twenty-two of these individuals had subsequently died during an eighteen-month period following assessment. Six years after testing, thirty-six of these individuals had died. Step-wise discriminant analyses at each occasion yielded functions defined by the KB subtests, measures of organicity and depression, age of institutionalization, sex, and length of institutionalization that differentiated survivors and nonsurvivors. These data suggested that the Kendrick Battery subtests, measures of depression and organicity, in combination with length of institutionalization and age of admittance predict death among the elderly, for the most part, replicating previous research.

Cognitive function and prediction of dementia in old age

Longitudinal changes in cognitive functioning were examined for a sample of aging twins, some of whom developed dementia while others did not. Individuals who were judged to be demented at a mean age of eighty-five years had achieved lower scores on most tests twenty years prior to diagnosis, and experienced greater declines in vocabulary and forward digit span over time, than those surviving to a comparable age without dementia. These trends were observed for individuals with mild, as well as moderate-to-severe, dementia and were unrelated to physical health status or premorbid activity patterns. It is suggested that dementing illness may develop very slowly, and that the likelihood of exhibiting clinically significant dementia may vary with premorbid intellectual level.

Cognitive impairment in late-life depression: clinical correlates and treatment implications

Elderly depressed inpatients with high vs. low scores on a quantitative mental status examination (the Mini-Mental State (MMS)) were compared with regard to demographic and clinical characteristics, treatment and short-term response, and functional status at 2-year follow-up. Low-MMS patients were less well educated and more likely to be delusional, anxious, and globally impaired than high-MMS patients. The two groups responded equally well to treatment, but the low-MMS group required a lengthier hospital stay and greater use of neuroleptic medications. The two groups also had similar long-term outcomes, although greater attrition was observed among cognitively impaired subjects.

P-technique comes of age. Multivariate, replicated, single-subject designs for research on older adults

The complexity of human behavior demands that research methods be capable of dealing with multivariate, multioccasion, multisubject data if successful explanatory accounts of behavior are to be constructed. When the research focus is on developmental phenomena such as aging, the complexity of the task is even greater because of the difficulties of modeling and accounting for systematic changes in behavior. Proper decisions about which research methods to use rest on four principal concerns: (1) general orientation of the research; (2) theoretical assumptions concerning the nature of the phenomenon being studied; (3) data collection strategy; and (4) data analysis tactics.

Replicated, multivariate, single-subject research designs such as P-technique involve assessment with multiple variables at each of many times of measurement. The resulting data, which are analyzed to determine the nature of occasion-to-occasion changes in the variables, can inform about both covariation patterns and level. Such designs have not been exploited by researchers in aging even though concern with a variety of intraindividual changes in older adulthood is evident in the literature. The rationale of such designs and their potential utility for the study of adult development and aging are examined and discussed.

Fuzzy and crisp set-theoretic-based classification of health and disease. A qualitative and quantitative comparison

Conventional cluster analyses of patient populations are intended to assist in the identification and characterization of groups that may represent etiological or pathological subtypes within a particular disease class. These methods have been criticized as being insensitive to subtle patient differences, which may be masked as a result of the all-or-nothing concept of cluster membership intrinsic to crisp set-theoretic-based grouping algorithms. As an alternative to conventional clustering procedures, several investigators have studied the use of fuzzy classification methods. In general, these measure a patient's clinical status in terms of a real number defined on the closed unit interval, reflecting the extent or degree to which a particular grouping entity characterizes the patient. This paper compares and contrasts the applications of crisp and fuzzy set-theoretic-based clustering procedures to a set of data describing the cognitive and intellectual functioning of a group of subjects participating in a longitudinal study of aging. Emphasis is placed on both qualitative and quantitative aspects corresponding, respectively, to the clinical interpretation of cluster definitions, and the robustness or sensitivity of the classification procedures to changes in patient profiles over time. The fuzzy set-theoretic-based model was found to be more sensitive to changes in subject level of functioning over time, to provide superior quantitative protrayals of patterns of aging, and to reflect properties of the aging process derived from other research.

Psychological changes from midlife to early old age: implications for the maintenance of mental health

Changes from midlife to old age are described and conceptual models of adult development are discussed to debunk some commonly held stereotypes. Effects of biological change on behavior; age differences in learning, memory, and motivation; and age changes in intelligence and personality are considered, including implications for primary prevention, diagnosis, and social intervention.