Increasing the sensitivity of functional status assessment in the preclinical range (normal to mild cognitive impairment): Exploring the IADL-Extended approach

Background/Aims: Dementia exhibits an insidious onset consisting of cognitive, behavioral, and functional impairment. We explored a functional continuum that extends assessment beyond the clinical instrumental activities of daily living (IADL) range and into advanced activities of daily living. Methods: We examined the predictive power (Cox regression; n = 2,471) of a unidimensional IADL-extended (IADL-x) scale for incident mild cognitive impairment (MCI). We also examined “time to MCI” as an outcome measure. Results: Each additional task endorsed on the IADL-x hierarchy (e.g., endorsing participation in 6 vs. 5 activities) resulted in a 10% reduction in MCI risk (HR 0.90, 95% CI 0.85–0.94, p < 0.001). For the fully adjusted model the risk reduction dropped to 6%. The odds of incident MCI within 2 years (for those below the median IADL-x total score) was 2.5 times higher (OR 2.60, 95% CI 1.52–4.4, p < 0.001) and 2 times higher for incident MCI within the next 5 years (OR 1.93, 95% CI 1.76–3.2, p < 0.01). Conclusion: The IADL-x metric appears to be a valid approach for determining the risk of MCI based on one’s position along a formal hierarchy of function

Functional Status in the Young-Old: Establishing a Working Prototype of an Extended-Instrumental Activities of Daily Living Scale

BACKGROUND: Instrumental activities of daily living (IADLs) exhibit strong predictive power for the presence of dementia and mild cognitive impairment. However, IADLs are often less effective in younger cohorts or in healthy community-dwelling samples, presenting with large ceiling effects. This study aimed to construct an IADL scale with an extended range. An effort was made to incorporate leisure activity tasks that were more stimulating, and potentially more challenging, into a set of traditional IADLs. METHODS: Beginning with a set of IADL and leisure activity items, nonparametric item response theory methodology was used to construct a scale with appropriate dimensionality, monotonicity, item discrimination power, and scalability within a large cohort of young-old (aged 65-75). Dimensionality was further scrutinized by principal component analysis of the residuals. The predictive validity of the resulting scale for poor cognitive performance was evaluated using logistic regression. RESULTS: A reliable (rho = .73) unidimensional construct was established, meeting the Mokken item response theory criteria of medium scalability. Excluding demented participants, the adjusted model proved sensitive to relatively subtle cognitive deficits; each additional task endorsed (nine-item scale) significantly decreased the odds of being in the bottom quarter of composite domains relating to processing speed (odds ratio = 0.73 [confidence interval: 0.56-0.97], p < .05) and visuospatial ability (odds ratio = 0.70 [confidence interval: 0.73-0.87], p < .01). CONCLUSIONS: A reliable extended-IADL scale was constructed meeting item response theory assumptions relating to unidimensionality, monotonicity, and invariant item ordering. The range of measurement extends well beyond traditional IADL scales. Finally, the scale appears to be sensitive to cognitive differences within the normal spectrum

The historical progression from ADL scrutiny to IADL to advanced ADL: assessing functional status in the earliest stages of dementia

Background: Decrements in instrumental activities (IADL) have been observed in the prodromal phase of dementia. Given the long predementia stage in neurodegenerative diseases, it has been proposed that subtle functional changes may precede clinical IADL impairment. Incorporating more challenging advanced ADLs (eg, volunteer work) into the assessment process may increase the sensitivity of functional measures, thus expanding the window for monitoring or interventions. Methods: Longitudinal cohort study was used (follow-ups, 18–24 month), with subjects aged 60 and older (n = 3,635). To elucidate the relationship between cognitive ability and functional status we employed an IADL scale with an extended range (ADL-extended; includes IADL but also more challenging advanced ADLs) that meets item response theory properties of dimensionality, monotonicity, and item hierarchy. Procedures involved (a) a dynamic change model employed to inspect the temporal relationship between ADL-extended and cognitive status and (b) Cox proportional hazards to assess the risk of incident dementia based on ADL-extended scores. Results: Growth curve modeling: baseline ADL-extended was significantly associated with all four cognitive domains investigated. Worse baseline ADL-extended was associated with more rapid declines in speed/executive function, and worse baseline memory was associated with more rapid declines in ADL-extended; a concurrent association was found for language and ADL-extended. Cox model: the risk of dementia was decreased for each additional ADL-extended item endorsed (hazard ratio [HR], 0.85; 95% confidence interval = 0.81–0.90). Conclusions: An increased risk of dementia could be observed in the ADL-extended items, which reflects an area of the functional continuum beyond IADL competencies

Calibrating ADL-IADL scales to improve measurement accuracy and to extend the disability construct into the preclinical range: a systematic review

<p>Abstract</p> <p>Background</p> <p>Interest in measuring functional status among nondisabled older adults has increased in recent years. This is, in part, due to the notion that adults identified as 'high risk' for functional decline portray a state that is potentially easier to reverse than overt disability. Assessing relatively healthy older adults with traditional self-report measures (activities of daily living) has proven difficult because these instruments were initially developed for institutionalised older adults. Perhaps less evident, are problems associated with change scores and the potential for 'construct under-representation', which reflects the exclusion of important features of the construct (e.g., disability). Furthermore, establishing a formal hierarchy of functional status tells more than the typical simple summation of functional loss, and may have predictive value to the clinician monitoring older adults: if the sequence task difficulty is accelerated or out of order it may indicate the need for interventions.</p> <p>Methods</p> <p>This review identified studies that employed item response theory (IRT) to examine or revise functional status scales. IRT can be used to transform the ordinal nature of functional status scales to interval level data, which serves to increase diagnostic precision and sensitivity to clinical change. Furthermore, IRT can be used to rank items unequivocally along a hierarchy based on difficulty. It should be noted that this review is not concerned with contrasting IRT with more traditional classical test theory methodology.</p> <p>Results</p> <p>A systematic search of four databases (PubMed, Embase, CINAHL, and PsychInfo) resulted in the review of 2,192 manuscripts. Of these manuscripts, twelve met our inclusion/exclusion requirements and thus were targeted for further inspection.</p> <p>Conclusions</p> <p>Manuscripts presented in this review appear to summarise gerontology's best efforts to improve construct validity and content validity (i.e., ceiling effects) for scales measuring the early stages of activity restriction in community-dwelling older adults. Several scales in this review were exceptional at reducing ceiling effects, reducing gaps in coverage along the construct, as well as establishing a formal hierarchy of functional decline. These instrument modifications make it plausible to detect minor changes in difficulty for IADL items positioned at the edge of the disability continuum, which can be used to signal the onset of progressive type disability in older adults.</p

Improving a measure of mobility-related fatigue (the mobility-tiredness scale) by establishing item intensity

OBJECTIVES: To improve the construct validity of self-reported fatigue by establishing a formal hierarchy of scale items and to determine whether such a hierarchy could be maintained across time (aged 75–80), sex, and nationality. DESIGN: Cohort study. SETTING: Two Nordic urban locations: Jyväskylä, Finland, and Glostrup, Denmark. PARTICIPANTS: Baseline (1989/90) consisted of a random sample of citizens of Finland or Denmark born in 1914 (n = 837). At 5-year follow-up, excluding those lost to follow-up and with baseline disability resulted in a sample of n = 690. MEASUREMENTS: The Mobility-Tiredness (Mob-T) Scale is a six-item scale that requires subjects to self-report on whether they become tired performing mobility-related tasks. Employing item response theory, an attempt was made to enhance construct validity by confirming a hierarchy of mobility-related fatigue. RESULTS: A formal hierarchy of fatigue tasks, maintained across time, was established using the revised Mob- T Scale. At age 75, the scalability statistics were a homogeneity coefficient (H) of 0.80, [Formula: see text] of 3.9% and an H(T) value of 0.66. The corresponding figures at age 80 were 0.75, 6.9% and 0.59. The property of invariant item ordering was maintained across subgroups based on sex and nationality. CONCLUSION: Establishing a formal hierarchy at age 75 allowed which tasks were most debilitating to be identified more clearly and the individual’s “distance” from these tasks to be gauged. Because it was possible to confirm that the item hierarchy was maintained across time (aged 75–80), researchers or clinicians can be more confident that performance over time is the result of real change and has less to do with measurement error

Cognitively Engaging Activity is Associated with Greater Cortical and Subcortical Volumes

As the population ages and dementia becomes a growing healthcare concern, it is increasingly important to identify targets for intervention to delay or attenuate cognitive decline. Research has shown that the most successful interventions aim at altering lifestyle factors. Thus, this study examined how involvement in physical, cognitive, and social activity is related to brain structure in older adults. Sixty-five adults (mean age = 71.4 years, standard deviation = 8.9) received the Community Healthy Activities Model Program for Seniors (CHAMPS), a questionnaire that polls everyday activities in which older adults may be involved, and also underwent structural magnetic resonance imaging. Stepwise regression with backwards selection was used to predict weekly time spent in either social, cognitive, light physical, or heavy physical activity from the volume of one of the cortical or subcortical regions of interest (corrected by intracranial volume) as well as age, education, and gender as control variables. Regressions revealed that more time spent in cognitive activity was associated with greater volumes of all brain regions studied: total cortex (β = .289, p = .014), frontal (β = .276, p = .019), parietal (β = .305, p = .009), temporal (β = .275, p = .020), and occipital (β = .256, p = .030) lobes, and thalamus (β = .310, p = .010), caudate (β = .233, p = .049), hippocampus (β = .286, p = .017), and amygdala (β = .336, p = .004). These effects remained even after accounting for the positive association between cognitive activity and education. No other activity variable was associated with brain volumes. Results indicate that time spent in cognitively engaging activity is associated with greater cortical and subcortical brain volume. Findings suggest that interventions aimed at increasing levels of cognitive activity may delay cognitive consequences of aging and decrease the risk of developing dementia