Background

The expected increase in the prevalence of dementia in ageing populations is a major concern both from a health and an economic point of view. Dementia is currently without actual cure but symptom progression may be delayed if risk factors for cognitive impairment are diagnosed and treated at an early stage. The general aim of this and related projects is to exploit the international variation of health and life circumstances in order to identify which interactions of health and socio-economic conditions over the life course affect cognition in later life. The understanding of such life-course pathways to first mild cognitive impairment and then, possibly, dementia, should help in developing preventive early interventions. The study of older adults in a diverse array of countries will provide valuable information on cognitive status and relate it to the socio-economic and social environment of the elderly as well as biomarkers that may serve as instruments to target early prevention measures. It will enhance our understanding how the vastly differing social, health and long-term care systems affect mental health and resulting mortality of the aging populations. This holds especially for the life circumstances in Europe since World War II, which are likely to have influenced cognitive decline now at older ages. Moreover, the large variation in key policy variables, e.g. retirement age, identifies pathways from early retirement through inactivity and loss of social contacts to lower cognition, mediated by education, working environment and other socio-economic factors over the life-course.

Abstract

The project leverages the EU-funding of the Survey of Health, Aging and Retirement in Europe (SHARE) and the harmonization efforts with the US Health and Retirement Study (HRS) and the English Longitudinal Study of Ageing (ELSA) funded by NIA in earlier waves. SHARE is a large population-representative panel in currently 28 Continental European countries. Strictly harmonized health variables include self-reported health, ADLs and IADLs, physical measurements such as grip strength, peak flow and chair stand, and a large battery of tests for cognition and mental health. Moreover, SHARE has collected dried blood spot (DBS) samples from some 27,000 respondents in a subset of 13 countries. Some markers correlating with cognitive decline have been assayed in Denmark at the Statens Serum Institute (SSI), including cytokines and blood-based proteins such as BDNF and APOE4. The collection of biomarkers is a crucial part of the international harmonization strategy aimed at minimizing the effects of different response styles to self-reported health questions across countries.

The project fills a strategic gap in this harmonization effort as the measurement of cognition in SHARE lacks the in-depth measurement according to the HCAP that has been designed for the HRS-style aging surveys supported by NIA. Filling this gap will permit a more accurate identification of mild and severe cognitive impairment in SHARE and the identification of biological and socio-economic characteristics associated with cognitive decline in later life.

Specific Aims

The project has three specific aims:

1. Administer HCAP in five SHARE countries (Czech Republic, Denmark, France, Germany, and Italy) in a randomly drawn stratified study sample of about 2,700 respondents following the same protocols and applying the same measures as HRS.
2. Analyze the collected data to assess the cognitive status (normal, mild and severe cognitive impairment) in the study sample; extrapolate the cognitive status to the full SHARE sample using the cognition measures and other covariates; compute country-specific prevalence rates of mild and severe cognitive impairment; compare these with HRS and other countries in the HCAP studies; and exploit the international variation of the SHARE plus HCAP data in order to identify which interactions of biomedical and socioeconomic conditions over the life course affect cognition later in life.
3. Create a user-friendly database, archive it and document all tasks and results of the project.

This project is synchronized with the long-run agenda of the SHARE panel, which has collected DBS in wave 6, has administered a life-history module in Wave 3 and 7, featured an extended cognition module from Wave 8 onwards, and administered SHARE-HCAP in Wave 9.

The project has achieved its first aim with a very satisfactory response rate, see the

Release 1.0 Note.

MEA then processed the raw data from the different countries and constructed an estimate of the cognitive status (normal, mild and severe cognitive impairment) in the SHARE-HCAP sample. The release paper describes the methodology, some descriptive results, and some caveats to the scientific community. These data are available on the SHARE website in the data section under “accompanying data sets”. Moreover, MEA used the SHARE-HCAP results to estimate the prevalence of dementia in all 28 SHARE countries and how it is related to the education of the respondents that they received when they were young, see the MEA Discussion Paper:

Cognitive Impairment and the Long Arm of Childhood Education: Evidence from Europe

Advisory Board

Prof. Dr. Karen Anderen-Ranberg	University of Southern Denmark, Odense University Hospital
Dr. Jens Benninghoff	kbo-Isar-Amper-Klinikum München-Ost
Prof. Dr. Bruno Dubois	Assistance Publique-Hôpitaux de Paris, Sorbonne University
Prof. Dr. Emrah Düzel	University Hospital Magdeburg, DZNE
Dr. Michael Hurd	RAND Center for the Study of Aging
Prof. Dr. Frank Jessen	University of Cologne, DZNE
Prof. Dr. Kenneth Langa	University of Michigan
Prof. Dr. Matt McGue	SDU,  Minnesota University
Prof. Dr. Robert Perneczky	University Hospital Munich, LMU
Prof. Dr. Anna Rieckmann	Bundeswehr University Munich
Prof. Dr. Andrew Steptoe	University College London
Prof. Dr. Annalena Venneri	Brunel University London
Prof. Dr. Michael Wagner	University Hospital Bonn, DZNE
Dr. David Weir	University of Michigan