Commentary: Life course epidemiology embraces geroscience

Multimorbidity burden and developmental trajectory in relation to later‐life dementia: A prospective study

INTRODUCTION

This study assessed the associations of multimorbidity burden and its developmental trajectory with later-life dementia.

METHODS

Among 5923 Health and Retirement Study participants, major chronic conditions including hypertension, diabetes mellitus, cancer, lung diseases, heart disease, stroke, psychological disorders, and arthritis were self- or proxy-reported in 1994-2008. Dementia diagnosis was self- or proxy-reported in 2008-2018. We used Cox regression to assess the associations of multimorbidity with incident dementia.

RESULTS

During follow-up (median = 8 years), 701 participants developed dementia. Each additional chronic condition in 2008 was related to 15% (confidence interval: 9% to 22%) higher hazard of dementia. Multimorbidity trajectories in 1994-2008 were classified as "rapid growth", "steady growth", "slow growth", and "no new condition" by the group-based trajectory modelling methods. Compared to "no new condition", the "rapid growth" trajectory was related to 32% (3% to 69%) higher dementia risk.

CONCLUSIONS

Both multimorbidity burden and its developmental trajectory were prospectively associated with risk of dementia.

Walking Speed Drives the Prognosis of Older Adults with Cardiovascular and Neuropsychiatric Multimorbidity

BACKGROUND

We investigated the impact of multiple cardiovascular and neuropsychiatric diseases on all-cause and cause-specific mortality in older adults, considering their functional status.

METHODS

This cohort study included 3241 participants (aged ≥60 years) in the Swedish National study of Aging and Care in Kungsholmen (SNAC-K). Number of cardiovascular and neuropsychiatric diseases was categorized as 0, 1, or ≥2. Functional impairment was defined as walking speed of <0.8m/s. Death certificates provided information on 3- and 5-year mortality. Hazard ratios (HR) were derived from Cox models (all-cause mortality) and Fine-Gray competing risk models (cardiovascular and non-cardiovascular mortality).

RESULTS

After 3 years, compared with participants with preserved walking speed and without either cardiovascular or neuropsychiatric diseases, the multivariable-adjusted HR (95% confidence interval) of all-cause mortality for people with functional impairment in combination with 0, 1, and ≥2 cardiovascular diseases were 1.88 (1.29-2.74), 3.85 (2.60-5.70), and 5.18 (3.45-7.78), respectively. The corresponding figures for people with 0, 1, and ≥2 neuropsychiatric diseases were, respectively, 2.88 (2.03-4.08), 3.36 (2.31-4.89), and 3.68 (2.43-5.59). Among people with ≥2 cardiovascular or ≥2 neuropsychiatric diseases, those with functional impairment had an excess risk for 3-year all-cause mortality of 18/100 person-years and 17/100 person-years, respectively, than those without functional impairment. At 5 years, the association between the number of cardiovascular diseases and mortality resulted independent of functional impairment.

CONCLUSIONS

Functional impairment magnifies the effect of cardiovascular and neuropsychiatric multimorbidity on mortality among older adults. Walking speed appears to be a simple clinical marker for the prognosis of these two patterns of multimorbidity.

Association Between Speed of Multimorbidity Accumulation in Old Age and Life Experiences: A Cohort Study

Rapidly accumulating multiple chronic conditions (multimorbidity) during aging are associated with many adverse outcomes. We explored the association between 4 experiences throughout life-childhood socioeconomic circumstances, early-adulthood education, midlife occupational stress, and late-life social network-and the speed of chronic disease accumulation. We followed 2,589 individuals aged ≥60 years from the Swedish National Study on Aging and Care in Kungsholmen for 9 years (2001-2013). Information on life experiences was collected from detailed life-history interviews. Speed of disease accumulation was operationalized as the change in the count of chronic conditions obtained from clinical examinations, medical histories, laboratory data, drug use, and register linkages over 9 years. Linear mixed models were used to analyze the data. Speed of disease accumulation was lower in individuals with more than elementary education (for secondary, β × time = -0.065, 95% CI: -0.126, -0.004; for university, β × time = -0.118, 95% CI: -0.185, -0.050); for active occupations compared with high-strain jobs (β × time = -0.078, 95% CI: -0.138, -0.017); and for richer social networks (for moderate tertile, β × time = -0.102, 95% CI: -0.149, -0.055; for highest tertile, β × time = -0.135, 95% CI: -0.182, -0.088). The association between childhood circumstances and speed of disease accumulation was attenuated by later-life experiences. Diverse experiences throughout life might decelerate chronic disease accumulation during aging.

Multimorbidity and functional impairment-bidirectional interplay, synergistic effects and common pathways

This review discusses the interplay between multimorbidity (i.e. co-occurrence of more than one chronic health condition in an individual) and functional impairment (i.e. limitations in mobility, strength or cognition that may eventually hamper a person's ability to perform everyday tasks). On the one hand, diseases belonging to common patterns of multimorbidity may interact, curtailing compensatory mechanisms and resulting in physical and cognitive decline. On the other hand, physical and cognitive impairment impact the severity and burden of multimorbidity, contributing to the establishment of a vicious circle. The circle may be further exacerbated by people's reduced ability to cope with treatment and care burden and physicians' fragmented view of health problems, which cause suboptimal use of health services and reduced quality of life and survival. Thus, the synergistic effects of medical diagnoses and functional status in adults, particularly older adults, emerge as central to assessing their health and care needs. Furthermore, common pathways seem to underlie multimorbidity, functional impairment and their interplay. For example, older age, obesity, involuntary weight loss and sedentarism can accelerate damage accumulation in organs and physiological systems by fostering inflammatory status. Inappropriate use or overuse of specific medications and drug-drug and drug-disease interactions also contribute to the bidirectional association between multimorbidity and functional impairment. Additionally, psychosocial factors such as low socioeconomic status and the direct or indirect effects of negative life events, weak social networks and an external locus of control may underlie the complex interactions between multimorbidity, functional decline and negative outcomes. Identifying modifiable risk factors and pathways common to multimorbidity and functional impairment could aid in the design of interventions to delay, prevent or alleviate age-related health deterioration; this review provides an overview of knowledge gaps and future directions.

An International Perspective on Chronic Multimorbidity: Approaching the Elephant in the Room

Multimorbidity is a common and burdensome condition that may affect quality of life, increase medical needs, and make people live more years of life with disability. Negative outcomes related to multimorbidity occur beyond what we would expect from the summed effect of single conditions, as chronic diseases interact with each other, mutually enhancing their negative effects, and eventually leading to new clinical phenotypes. Moreover, multimorbidity mirrors an accelerated global susceptibility and a loss of resilience, which are both hallmarks of aging. Due to the complexity of its assessment and definition, and the lack of clear evidence steering its management, multimorbidity represents one of the main current challenges for clinicians, researchers, and policymakers. The authors of this article recently reflected on these issues during two twin international symposia at the 2016 European Union Geriatric Medicine Society (EUGMS) meeting in Lisbon, Portugal, and the 2016 Gerontological Society of America (GSA) meeting in New Orleans, USA. The present work summarizes the most relevant aspects related to multimorbidity, with the ultimate goal to identify knowledge gaps and suggest future directions to approach this condition.