Validation of the CogDrisk Instrument as Predictive of Dementia in Four General Community-Dwelling Populations

BACKGROUND

Lack of external validation of dementia risk tools is a major limitation for generalizability and translatability of prediction scores in clinical practice and research.

OBJECTIVES

We aimed to validate a new dementia prediction risk tool called CogDrisk and a version, CogDrisk-AD for predicting Alzheimer's disease (AD) using cohort studies.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Four cohort studies were identified that included majority of the dementia risk factors from the CogDrisk tool. Participants who were free of dementia at baseline were included. The predictors were component variables in the CogDrisk tool that include self-reported demographics, medical risk factors and lifestyle habits. Risk scores for Any Dementia and AD were computed and Area Under the Curve (AUC) was assessed. To examine modifiable risk factors for dementia, the CogDrisk tool was tested by excluding age and sex estimates from the model.

RESULTS

The performance of the tool varied between studies. The overall AUC and 95% CI for predicting dementia was 0.77 (0.57, 0.97) for the Swedish National study on Aging and Care in Kungsholmen, 0.76 (0.70, 0.83) for the Health and Retirement Study - Aging, Demographics and Memory Study, 0.70 (0.67,0.72) for the Cardiovascular Health Study Cognition Study, and 0.66 (0.62,0.70) for the Rush Memory and Aging Project.

CONCLUSIONS

The CogDrisk and CogDrisk-AD performed well in the four studies. Overall, this tool can be used to assess individualized risk factors of dementia and AD in various population settings.

Rapidly developing multimorbidity and disability in older adults: does social background matter?

BACKGROUND

Multimorbidity is among the most disabling geriatric conditions. In this study, we explored whether a rapid development of multimorbidity potentiates its impact on the functional independence of older adults, and whether different sociodemographic factors play a role beyond the rate of chronic disease accumulation.

METHODS

A random sample of persons aged ≥60 years (n = 2387) from the Swedish National study on Aging and Care in Kungsholmen (SNAC-K) was followed over 6 years. The speed of multimorbidity development was estimated as the rate of chronic disease accumulation (linear mixed models) and further dichotomized into the upper versus the three lower rate quartiles. Binomial negative mixed models were used to analyse the association between speed of multimorbidity development and disability (impaired basic and instrumental activities of daily living), expressed as the incidence rate ratio (IRR). The effect of sociodemographic factors, including sex, education, occupation and social network, was investigated.

RESULTS

The risk of new activity impairment was higher among participants who developed multimorbidity faster (IRR 2.4, 95% CI 1.9-3.1) compared with those who accumulated diseases more slowly overtime, even after considering the baseline number of chronic conditions. Only female sex (IRR for women vs. men 1.6, 95% CI 1.2-2.0) and social network (IRR for poor vs. rich social network 1.7, 95% CI 1.3-2.2) showed an effect on disability beyond the rate of chronic disease accumulation.

CONCLUSIONS

Rapidly developing multimorbidity is a negative prognostic factor for disability. However, sociodemographic factors such as sex and social network may determine older adults' reserves of functional ability, helping them to live independently despite the rapid accumulation of chronic conditions.

Lifestyle factors related to mortality and survival: a mini-review

As the world's population ages, elderly people are becoming an increasingly important group that merits special attention with regard to health and social issues. Lifestyles affect health and survival at all ages, but the consequences of poor lifestyle behaviors may be different for elderly people than for younger adults. They can also be heavily dependent on exposure earlier in life. Our current state of knowledge is based predominantly on studies conducted among middle-aged adults or young elderly people. Moreover, studies are sparse throughout the entire older age spectrum, from 65 to 90 years. This article summarizes the evidence regarding the impact of lifestyle behaviors on mortality among elderly people. It focuses on behaviors modifiable by individual actions and public health interventions, such as smoking, obesity and sedentary behavior, which predispose numerous people to diseases that rank among the leading causes of death, including heart disease, cancer, stroke, diabetes and dementia. These factors not only shorten life but, when they occur together, also have a major impact on survival beyond that associated with each single lifestyle factor. We propose an integrated life course model to guide research on longevity to answer questions that remain open and to find new strategies to ensure a longer and healthier life for future generations.

The impact of chronic multimorbidity and disability on functional decline and survival in elderly persons. A community-based, longitudinal study

OBJECTIVE

We aimed to disentangle the effect of chronic multimorbidity and disability on 3-year functional decline and survival in the elderly.

DESIGN

Prospective cohort study with a mean of follow-up of 2.8 years.

SETTING

Swedish elderly persons from the Kungsholmen Project (1987-2000).

SUBJECTS

A total of 1099 subjects, 77-100 years old, living in the community and institutions.

MAIN OUTCOME MEASUREMENTS

Medical diagnoses (based on clinical examination, drug use, medical records and blood tests), and functional assessment (according to Katz Index) at baseline were investigated in relation to functional decline and death occurring during follow-up.

RESULTS

At baseline, 12.1% of participants had disability, and 52.3% were affected by multimorbidity. During follow-up, 363 persons died and 85 worsened in functioning. The number of chronic conditions incrementally increased the risk of functional decline [hazard ratio (HR) increased from 1.5 in subjects with one disease to 6.2 in persons with 4+ diseases]. However, this was not the case for mortality, as the HR of death was the same for people with one disease as well as 4+ diseases (HR=2.3). Baseline disability had the highest impact on survival, independently of number of diseases [HR=8.1; 95% confidence interval (CI)=4.8-13.7 in subjects with one disease and HR=7.7; 95% CI=4.7-12.6 in those with 2+ diseases].

CONCLUSIONS

In the elderly subjects, chronic disability rather than multimorbidity emerged as the strongest negative prognostic factor for functionality and survival.