With the continuing ageing of the world’s population, more than 150 million people are predicted to be living with dementia by 2050. The financial and societal burdens of this will be immense.
Modifiable risk factors for cognitive decline and dementia offer means to intervene and prevent or delay the onset of dementia. Most of the evidence for risk factors, however, comes from high-income countries, while the majority of people living with dementia are in low- and middle-income countries.
The prevalence of some risk factors for dementia, such as hypertension, diabetes and smoking, differs across countries or ethno-regions. There may also be ethno-regional differences in the strength of association between some risk factors and dementia.
The Cohort Studies of Memory in an International Consortium (COSMIC) investigates risk factors for cognitive decline and dementia globally by combining and comparing data from population-based longitudinal cohort studies internationally. We aim for findings that will translate into interventions optimised for particular ethno-regions or populations. COSMIC currently has 44 member studies representing 33 different countries from regions that include Africa and the Middle East, Asia, Australia, Europe, North America, and South and Central America. To date, these cohort studies have a combined sample size of over 115,000 individuals.
COSMIC has reported on various risk factors for cognitive decline and dementia across a diverse geographical landscape. Importantly, we have identified differences in the effects of some risk factors across ethno-regions or populations.
This includes stronger associations for Asian people than for White people between smoking and poorer cognition, and between diabetes and cognitive decline. We have also investigated effects of childbirth, sedentary behaviour, depression and education, as well as explored ethno-regional differences in the prevalence of mild cognitive impairment and subjective cognitive decline.
Perminder Sachdev, the lead investigator of COSMIC, said: “Dementia is a global problem. The epidemiology of dementia therefore needs a global approach, and COSMIC comes close to achieving that goal.”
Fourteen papers have been published and there are nearly 20 current COSMIC projects managed by researchers associated with our member studies or external to COSMIC, on topics including alcohol use, nutrition, physical activity and social health. One of these projects involves a collaboration on the Global Burden of Disease (GBD) study with the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.
We have also recently begun creating Dementias Platform Australia (DPAU), an online portal that will streamline the discovery and availability of COSMIC data to researchers across the globe. We currently welcome applications to use COSMIC data from qualified researchers anywhere in the world, with our website containing more details and a research proposal form.
We are also keen to recruit new member studies, particularly those from under-represented regions or populations that will enable us to investigate and compare risk factors for cognitive decline and dementia across a larger range of ethno-regions or populations, including African Americans and Hispanics.
For further information, please see the protocol paper1 or contact the COSMIC coordinator, Dr Darren Lipnicki at firstname.lastname@example.org.
Sachdev et al. COSMIC (Cohort Studies of Memory in an International Consortium): an international consortium to identify risk and protective factors and biomarkers of cognitive ageing and dementia in diverse ethnic and sociocultural groups. BMC Neurol. 2013;13:165. BMC Neurol. 2013 Nov 6;13:165 (PDF).
COSMIC is an Australian-led collaboration by the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney and is funded until 2022 by the National Institute On Aging of the National Institutes of Health, USA. CHeBA’s website has more details on member studies, publications, and current projects.