Karr et al., 2018. When does cognitive decline begin?

Karr, J. E., Graham, R. B., Hofer, S. M., & Muniz-Terrera, G. (2018). 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. Psychology and Aging, 33(2), 195-218.

Year: 
2018
Status: 
complete
Abstract: 

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 (c) 2018 APA, all rights reserved)

 

Praetorius Björk et al., 2016. 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

Björk, M. P., Johansson, B., & Hassing, L. B. (2016). 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. Neurobiology of aging, 38, 68-72.

Year: 
2016
Status: 
complete
Abstract: 

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.

    Muniz-Terrera et al., 2012. Investigating terminal decline: results from a UK population-based study of aging.

    Muniz-Terrera, G., van den Hout, A., Piccinin, A. M., Matthews, F. E., & Hofer, S. M. (2013). Investigating terminal decline: Results from a UK population-based study of aging. Psychology and aging, 28(2), 377.

    Year: 
    2012
    Status: 
    complete
    Abstract: 

    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. (PsycINFO Database Record (c) 2016 APA, all rights reserved)

    Cadar et al., 2016. The role of cognitive reserve on terminal decline: a cross-cohort analysis from two European studies

    Cadar, D., Stephan, B. C., Jagger, C., Johansson, B., Hofer, S. M., Piccinin, A. M., & Muniz‐Terrera, G. (2016). The role of cognitive reserve on terminal decline: A cross‐cohort analysis from two European studies: OCTO‐Twin, Sweden, and Newcastle 85+, UK. International Journal of Geriatric Psychiatry, 31(6), 601-610.

    Year: 
    2017
    Status: 
    complete
    Abstract: 

    OBJECTIVE: Cognitive performance shows a marked deterioration in close proximity to death, as postulated by the terminal decline hypothesis. The effect of education on the rate of terminal decline in the oldest people (i.e. persons 85+ years) has been controversial and not entirely understood. In the current study, we investigated the rate of decline prior to death with a special focus on the role of education and socioeconomic position, in two European longitudinal studies of ageing: the Origins of Variance in the Old-Old: Octogenarian Twins (OCTO-Twin) and the Newcastle 85+ study.

    METHODS: A process-based approach was used in which individuals' cognitive scores were aligned according to distance to death. In a coordinated analysis, multilevel models were employed to examine associations between different markers of cognitive reserve (education and socioeconomic position) and terminal decline using the mini-mental state examination (MMSE), controlling for age at baseline, sex, dementia incidence and time to death from the study entry to the time of death within each cohort.

    RESULTS: The current findings suggest that education was positively associated with higher MMSE scores prior to death in the OCTO-Twin, but not in the Newcastle 85+ study, independent of socioeconomic position and other factors such as baseline age, sex and time to death from the study entry. However, education was not associated with the rate of terminal decline in both of these studies.

    CONCLUSIONS: Our results offer only partial support to the cognitive reserve hypothesis and cognitive performance prior to death.

    PIccinin et al., 2011. Terminal Decline From Within- and Between-Person Perspectives, Accounting for Incident Dementia

    Piccinin, A.M., Muniz, G., Matthews, F. & Johansson, B. (2011). Terminal decline from within and between person perspectives, accounting for incident dementia. Journal of Gerontology: Psychological Sciences, 66(4), 391-401.

    Year: 
    2011
    Status: 
    complete
    Presentation Citations: 

    Muniz, G., Piccinin, A.M., Johansson, B. Matthews, F. & Hofer, S. M. (November, 2011). Do all individuals experience a change in age-related cognitive decline? In A.M. Piccinin & G. Muniz (Chairs), Advances in Understanding Cognitive Aging: Longitudinal Research on Change, Variation, and Plasticity. Symposium conducted at the 64th Annual Scientific Meeting of the Gerontological Society of America, Boston, MA.

    Abstract: 

    Objective: The terminal cognitive decline hypothesis has been debated for almost 50 years. This hypothesis implies a change in rate of decline within an individual. Therefore, we examine the hypothesis from a within-person perspective using a time to death chronological structure.

    Method: Scores on a Swedish version of the Wechsler Adult Intelligence Scale Information and Block Design scores from 461 OCTO-Twin Study participants with confirmed death dates were modeled using quadratic growth curve models including both age and distance from death at study entry, sex, education, and dementia diagnosis as covariates of initial performance and of linear and quadratic change over time.

    Results: Information scores showed statistically significant evidence of slight within-person acceleration of declines in the no dementia group. Individuals with incident dementia declined more quickly, and those who were closer to death at study baseline had a stronger acceleration. Block Design scores declined but did not show evidence of such acceleration either within or across individuals: Decline was faster in incident cases closer to death at study entry.

    Discussion. Within-person evidence of terminal decline is not as strong as previously published between-person results. Strategies for focusing models on longitudinal aspects of available data and the extent to which lack of within-person evidence for terminal decline may stem from common data limitations are discussed.

    Friedman et al., 2015. Inflammation Partially Mediates the Association of Multimorbidity and Functional Limitations in a National Sample of Middle-Aged and Older Adults: The MIDUS Study

    Friedman, E. M., Christ, S. L., & Mroczek, D. K. (2015). Inflammation partially mediates the association of multimorbidity and functional limitations in a national sample of middle-aged and older adults: The MIDUS Study. Journal of aging and health, 27(5), 843-863.DOI: 10.1177/0898264315569453

    Year: 
    2015
    Status: 
    complete
    Abstract: 

    Objective: Older adults are increasingly likely to have two or more chronic medical conditions (multimorbidity) and are consequently at greater risk of disability. Here we examine the role of inflammation in mediating the relationship between multimorbidity and disability. 

    Method: Data are from the Survey of Mid-Life in the United States (MIDUS), a national sample of middle-aged and older adults. Structural equation models were used to assess direct relationships between multimorbidity and activities of daily living as well as indirect associations with a latent variable for inflammation (indicated by circulating levels of interleukin-6, C-reactive protein, and fibrinogen) as a mediator. 

    Results: After adjustment for potential confounds, multimorbidity was positively associated with inflammation (p < .001) and functional limitations (p < .001), and inflammation partially mediated the link between multimorbidity and functional limitations (p < .01). 

    Discussion: Inflammation may be an important biological mechanism through which chronic medical conditions are linked to disability in later life.

    Cadar et al., 2017. An International Evaluation of Cognitive Reserve and Memory Changes in Early Old Age in 10 European Countries.

    Cadar, D., Robitaille, A., Clouston, S., Hofer, S. M., Piccinin, A. M., & Muniz-Terrera, G. (2017). An international evaluation of cognitive reserve and memory changes in early old age in 10 European countries. Neuroepidemiology, 48(1-2), 9-20.

    Year: 
    2017
    Status: 
    complete
    Abstract: 

    Background: Cognitive reserve was postulated to explain individual differences in susceptibility to ageing, offering apparent protection to those with higher education. We investigated the association between education and change in memory in early old age. 

    Methods: Immediate and delayed memory scores from over 10,000 individuals aged 65 years and older, from 10 countries of the Survey of Health, Ageing and Retirement in Europe, were modeled as a function of time in the study over an 8-year period, fitting independent latent growth models. Education was used as a marker of cognitive reserve and evaluated in association with memory performance and rate of change, while accounting for income, general health, smoking, body mass index, gender, and baseline age. 

    Results: In most countries, more educated individuals performed better on both memory tests at baseline, compared to those less educated. However, education was not protective against faster decline, except for in Spain for both immediate and delayed recall (0.007 [SE = 0.003] and 0.006 [SE = 0.002]), and Switzerland for immediate recall (0.006 [SE = 0.003]). Interestingly, highly educated Italian respondents had slightly faster declines in immediate recall (-0.006 [SE = 0.003]). 

    Conclusions: We found weak evidence of a protective effect of education on memory change in most European samples, although there was a positive association with memory performance at individuals' baseline assessment.

    Bendayan et al., 2017. Hierarchy and Speed of Loss in Physical Functioning: A Comparison Across Older U.S. and English Men and Women.

    Bendayan, R., Cooper, R., Wloch, E. G., Hofer, S. M., Piccinin, A. M., & Muniz-Terrera, G. (2016). Hierarchy and speed of loss in physical functioning: A comparison across older US and English men and women. Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences, 72(8), 1117-1122.

    Year: 
    2017
    Status: 
    complete
    Abstract: 

    Background: We aimed to identify the hierarchy of rates of decline in 16 physical functioning measures in U.S. and English samples, using a systematic and integrative coordinated data analysis approach.

    Methods: The U.S. sample consisted of 13,612 Health and Retirement Study participants, and the English sample consisted of 5,301 English Longitudinal Study of Ageing participants. Functional loss was ascertained using self-reported difficulties performing 6 activities of daily living and 10 mobility tasks. The variables were standardized, rates of decline were computed, and mean rates of decline were ranked. Mann–Whitney U tests were performed to compare rates of decline between studies.

    Results: In both studies, the rates of decline followed a similar pattern; difficulty with eating was the activity that showed the slowest decline and climbing several flights of stairs and stooping, kneeling, or crouching the fastest declines. There were statistical differences in the speed of decline in all 16 measures between countries. American women had steeper declines in 10 of the measures than English women. Similar differences were found between American and English men.

    Conclusions: Reporting difficulties climbing several flights of stairs without resting, and stooping, kneeling, or crouching are the first indicators of functional loss reported in both populations.