15 Feb 2016
PROFESSOR PERMINDER SACHDEV
This article was first published in InformAge, Volume 2, Issue IV December 2015 (Summer).
Dementia is a global problem, and there is a worldwide effort to identify risk and protective factors, determine early biomarkers, and develop novel treatments for dementia. A survey of the international research scene reveals that many groups are working in relative isolation on projects that are similar to research conducted elsewhere. Very often, the individual projects are not large enough to provide conclusive answers to complex research questions. A recent international trend to pool data from diverse settings allows researchers to harness the power of big data to answer questions more definitively and at a level that small sample sizes cannot provide. This has been particularly successful in the field of genetics, in which large consortia have emerged, helping identify novel disease genes and mechanisms of disease development.
Our research group at the Centre for Healthy Brain Ageing (CHeBA) is applying the same approach to the epidemiology of dementia, to discover its most important risk and protective factors. Since dementia is generally associated with ageing (with some exceptions), we believe that the best approach to understanding its determinants is to study healthy people as they grow old to examine who develops dementia and who escapes it. Over the last decade, we have launched a number of such studies – the Sydney Memory and Ageing study [1], the Sydney Stroke Study [2], the Older Australian Twins Study [3] and the Sydney Centenarian Study [4] – to examine who develops cognitive impairment or dementia, and why. We examine the participants of these studies every 1-2 years with detailed medical and neuropsychiatric testing, and obtain brain scans, blood tests, genetic analysis, etc. to document full profiles as they age. Even though these studies are large in the Australian context (e.g. the Memory and Ageing Study began with 1037 Australians), the numbers are insufficient to address many of the key questions on brain ageing and dementia.
In response, CHeBA is developing international consortia of studies with similar design and objectives, so that we can bring the data from these studies together and examine for commonalities as well as differences. The first was the COSMIC consortium [5] which now has 27 studies from all six continents that examine ageing and cognition in their populations, comprising over 50,000 individuals. The goodwill between researchers and the generosity in sharing data have been truly inspiring. The initial question addressed was: why do rates of Mild Cognitive Impairment (MCI) reported by different studies vary so much, from 4% to as high as 35%? The COSMIC data showed that once the definition of MCI was standardised, the variation in rates was much more modest, being of the order of 6-10%. Our researchers are now studying the rates of decline in cognition in older people in different parts of the world, and the reasons for any differences.
A second consortium, STROKOG, recently brought together 26 studies across 17 countries that are examining the development of dementia after stroke, comprising >10,000 individuals. This consortium will address salient questions in relation to vascular dementia and its overlap with Alzheimer’s disease.
The third consortium is the International Centenarian Consortium on Dementia (ICC-Dementia) which includes 15 studies of centenarians from Japan, USA, Europe and Australia. This consortium will address the difficult question of reliably identifying dementia in the extremely old – the fastest growing group in our population – and discovering the reasons why some individuals can live beyond 100 and yet escape dementia.
Research involving large data sets is expensive and involves highly skilled statisticians, psychologists and demographers, and CHeBA launched The Dementia Momentum® to harness philanthropic funds for this research effort. Our next objective is to launch a large trial delivered on the web to prevent dementia, which would involve about 18,000 Australians, and we are beginning the ground work for this trial, called Maintain Your Brain. This will be informed by data from the above consortia and other smaller trials that are currently in progress, but will be the first large scale trial world-wide to seek definitive evidence on whether dementia can be delayed if not prevented. The trial recently received funding from the National Health and Medical Research Council.
While consortia in genetics and epidemiology are leading the way, similar efforts should occur in other fields of ageing and dementia research. Aged care and retirement living settings offer an excellent opportunity for large scale research that can have a transformative effect on the care of the elderly with and without dementia, as shared and unique features of diverse settings can help inform the best practices and interventions for both longevity and optimal quality of life. CHeBA will endeavour to bring about such partnerships in the future.
References
- Sachdev P, Brodaty H, Reppermund S, Kochan N, Trollor J, Draper B, Slavin M, Crawford J, Kang K, Broe GA, and the Memory & Ageing Study Team. The Sydney Memory and Ageing Study (MAS): methodology and baseline medical and neuropsychiatric characteristics of an elderly epidemiological non-demented cohort of Australians aged 70-90 years. Int Psychogeriatr. 2010 Dec; 22(8):1248-1265.
- Sachdev PS, Lipnicki DM, Crawford JD, Wen W, Brodaty H. Progression of cognitive impairment in stroke/TIA patients over 3 years. J Neurol Neurosurg Psychiatry. 2014 Dec; 85(12):1324-30.
- Sachdev PS, Lammel A, Trollor JN, Lee T, Wright MJ, Ames D, Wen W, Martin NG, Brodaty H, Schofield PR, and the OATS Research Team. A comprehensive neuropsychiatric study of elderly twins: The Older Australian Twins Study. Twin Res Human Genet. 2009 Dec; 12(6):573-582.
- Sachdev PS, Levitan C, Crawford J, Sidhu M, Slavin M, Richmond R, Kochan N, Brodaty H, Wen W, Kang K, Mather KA, Sydney Centenarian Study Team. The Sydney Centenarian Study: methodology and profile of centenarians and near-centenarians. Int Psychogeriatr. 2013 Jun; 25(6):993-1005.
- Sachdev PS, Lipnicki DM, Kochan NA, 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 Nov; 13(1):165.
