Dorota Chapko is a PhD candidate in Public Health at the University of Aberdeen in Scotland, and a graduate from the Massachusetts Institute of Technology (MIT) with a double-major in Brain & Cognitive Sciences and in Anthropology. In this blog she discusses her recent Age & Ageing paper on the triad of impairment; she tweets at @dorotachapko
Although frailty is a central concept in clinical assessment of older people, there is no consensus definition. The concept is certainly multifactorial but physical components dominate. However, it is known that age-associated physical decline is likely to be accompanied by cognitive and emotional deficits. The ‘triad of impairment’ (triad) recognises the co-occurrence of cognitive, emotional and physical deficits in late-life and might be a useful alternative to ‘frailty’.
Identification of pathways to prolong healthy living and decrease the degree of frailty in old age will have benefits for individuals and society. Employment is often undertaken until ~70 years of age and is a major feature of socioeconomic circumstances. Childhood mental ability is a major influence on educational achievements, work experience and opportunities for work-related training. Both factors are potentially modifiable in early-life and, due to their accumulating impact over the life-course, may determine a delayed onset of functional decline. In our recently published manuscript in Age and Ageing, we investigated how mid-life occupational profile and childhood mental abilities contribute to triad in late-life.
For this purpose, we analysed data from the Aberdeen Birth Cohort of 1936 (ABC1936) characterised by the almost unique availability of childhood mental abilities. We used a series of careful data reduction approaches and structural equation models to understand the relationships between the life-course risks for triad. We found that childhood mental abilities at age 11 has almost 2 times greater protective effect on triad than mid-life occupational profile. Simultaneously, primary lifetime occupations with greater complexity associated with working with data or people, higher social status and employment stress in mid-life, though less influential than childhood mental abilities, also had a significant effect on triad. Our statistical approach indicated that triad may provide a useful alternative to a frailty measure.
A major implication of our work is that clinical studies should consider a life-course perspective, with a focus on early-life, to accurately assess and to improve the health of older adults. Importantly, childhood mental abilities had a predominant effect on triad, emphasising the importance of successful cognitive development. Brain structure in early- and late-life is influenced by childhood socioeconomic status pointing to the importance of early-life environment such as better nutrition, access to health care and education. Further research should establish whether the occupational profile acts as a moderator in the relationship between brain burden and triad, and how the developing brain influences this relationship.
This is an interesting comment on an interesting paper. It usefully points out that of all the items that might influence late life impairment in a triad of high order functions (cognition, affect, physical functioning) a few (childhood intelligence and how the complexity of demands of midlife occupation) seem to be especially influential. Clearly, to understand health in late life, and how it might be improved, knowing what it has been throughout life is also important, as is knowing about life circumstances, including socioeconomic factors.
I get all that and endorse it. It’s the authors’ next conclusion that I am less clear about. The paper and the blog see measuring cognition, affect and function as a “useful alternative” to the idea of frailty, which as they note, has no clear consensus definition. Even so, to say, as the paper says in its opening paragraph that “Cognitive decline and depressive symptoms independently contribute to frailty but are not yet incorporated into its definition…”is to take too narrow a view [Searle & Rockwood Alzheimers Res Ther 2015 PMID: 26240611].
A life course approach is entirely compatible with understanding frailty as deficit accumulation. Indeed, much as an immigrant person’s accent reflects the age at which they migrated, so too does their degree of frailty in general [Brothers et al., Arch Gerontol Geriatr. 2014; PMID: 23993266 ] and their cognitive and motor performance in particular [Brothers et al, Can Geriatr J 2014; PMID: 25232369] reflect the age at which they migrated from their birth country in relation to its national income levels, compared with that of their country of residence. Similarly, the degree of frailty in old age can reflect socioeconomic inequalities across the life course [Herr et al., Ann Epidemiol. 2015; PMID: 26117589].
Late life health is a complicated business. There are a large number of ways of approaching it, each offering some insight. For example, a recent report from the MRC Cognitive Functioning and Ageing Study cohorts addressed the question of whether the health of older adults had improved over a 20 year period. The answer depended to some extent on how health was defined (in that report by self-rated general assessment, by cognition, or by degree of disability).[Jagger et al., Lancet 2016; PMID: 26680218] Definitions matter in general, and here too.
That childhood intelligence affects late life intelligence is not counter-intuitive, and its quantification is useful. The data presented by Chapko et al. clearly supports a life-course approach. So too does understanding frailty as deficit accumulation, which increases at comparable rates most everywhere [Rockwood & Mitnitski Clin Geriatr 2011 PMID:21093719] including across the adult life course [Mitnitski & Rockwood Biogerontology 2016 PMID:25972341]. By that account, understanding the impact of childhood intelligence on the intercept of the line relating adult deficit accumulation to age, and of occupation on the slope of that line, would also be a way to quantify life course effects on late life health. A compelling reason to pursue this is that health deficit accumulation increases the risk of impairment in both late life cognition [Seale op. cit.] and in function [Theou et al., Arch Gerontol Geriatr. 2012; PMID: 22459318].
In short, there is nothing about considering frailty that excludes a life course perspective: on the contrary, there is much to learn about what influences how deficits accumulate, and not just in old age. Second, impaired cognition and function (the jury is out on affect) are not alternatives to frailty: being integrative, high order functions, they are more like special cases of it. It is not for nothing that both occur in old age, where deficit accumulation is highest, or that broad-based interventions, like diet and exercise impact, will be broadly beneficial. When it comes to understanding big questions about health in old age, let’s not narrow our scope, especially when the insights, such as those proposed by Chapko et al. might be broadly applicable.