Modelling historical air pollution and dementia/cognitive decline - towards a life course approach

Air pollution has been linked with a variety of health problems. However, it has not hitherto been possible to investigate what role air pollution plays in the development of important chronic health conditions which develop over many years or decades, such as, for example, dementia (including Alzheimer disease and vascular dementia). This is due to little systematic monitoring of air pollution before the 1980s.

This project will attempt to remedy this research gap by producing modelled historical air pollution estimates for the mid-twentieth century using historical data on emission of various air pollutants (nitrogen dioxides [NOx], sulphur dioxide [SO2] and fine particulate matter [smaller than 2.5 micrometres or 10 micrometres in diameter; PM2.5 and PM10, respectively], in combination with historical meteorological conditions). We will then combine the pollution model output with two cohort studies: (a) a complete population narrow-age cohort (the Scottish Mental Survey 1947 cohort, N~70,000 all aged 11 in 1947) where dementia diagnoses have been ascertained through electronic health records and death certificates; and (b) a subset of this cohort (the Lothian Birth Cohort 1936 study, N~1000) who have had longitudinal cognitive testing and clinical dementia diagnoses ascertained since recruitment in 2004.

This project will allow us to demonstrate that it is possible to estimate historical air pollution data through modelling and to combine these data with existing cohort studies in order to investigate the life course origins of dementia. Future possibilities to extend this work include: (i) modelling air pollution over more time points to get a finer-grained idea of 'exposure' to air pollution throughout the course of life; (ii) linking the modelled air pollution data with further cohort studies in the UK, Europe, and internationally; and (iii) applying these principles to other chronic diseases, such as cardiovascular disease.

KEYWORDS: Air pollution, Dementia, Risk Factors, Life Course Epidemiology, Prevention, Modelling

STAKEHOLDERS: People with dementia and their families; the general population; Alzheimer Scotland (charity); the academic community; the media; Public Health

PEOPLE WITH DEMENTIA AND THEIR FAMILIES AND THE GENERAL POPULATION
Dr Russ was involved in setting up the Scottish Dementia Clinical Research Network's Patient and Public Involvement (PPI) group which now has around 200 members. This application has been shown to them and their feedback has been used to improve and clarify the submission. This is a selection of general comments about the application, all from different people:
"I think the feasibility study sounds really valuable and will help a lot."
"I would like to congratulate you on the sterling research you are engaged in. ... By the way, I do think you are on solid ground with your theories but it is not me you have to convince."
"I have reviewed your study and found it to be very clear and concise. As a layman I found it very interesting and an attractive prospect."
"After reading the document I felt enthusiastic and excited at the project and the 'research question' it is trying to answer."
"What an interesting project; it is sufficiently detailed and covers a great deal. The project itself is fantastic."

We will hold focus groups in four regions of Scotland (most likely Edinburgh, Glasgow, Tayside, and Aberdeen) open to people with dementia, their family, friends, or carers, and interested members of the general public. The aim of these groups will be to disseminate the findings of our research to people affected by dementia before anyone else, and also to seek their feedback on air pollution in general as a risk factor and our project in particular. Their feedback will guide the development of future work. These groups will be facilitated by Dr Russ and will follow a semi-structured approach.

ACADEMIC COMMUNITY
The findings generated by the proposed research project will be submitted for publication in high-impact peer-reviewed scientific journals as well as being submitted for presentation at national and international scientific conferences.

MEDIA
Dementia research often attracts a great deal of media interest. For example, Dr Russ' work has previously been featured in national and international newspapers, on BBC radio and television, and on numerous websites. We will seek to issue a press release whenever findings thought to be of general interest are published and will engage in interviews with interested media outlets.

Furthermore, we will tweet using the Alzheimer Scotland Dementia Research Centre Twitter account (@AlzScotDRC; currently 881 followers) and will collaborate with the University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology's Knowledge Exchange Officer (Dr Robin Morton) to produce a short Youtube video summarising our findings (as Dr Russ has previously done: https://www.youtube.com/watch?v=BojlhIJ_TI8).

PUBLIC HEALTH
Dementia is of enormous global importance and is projected to show substantial increases in the number of people affected, particularly in low-to-middle income countries. This project has the potential, in the longer term, to have substantial public health impact on this debilitating condition. This impact may be beyond the time-scale of the proposed project, but is potentially of ground-breaking importance.