RESEARCH INTERESTS

• Health behaviours as determinant of health
• Ageing
• Statistical methods 

The core of my work is on the impact of health behaviors on aging outcomes. I have shown the importance of the combined effect of health behaviors, and the importance of duration of unhealthy behaviors on both cognitive and motor function. Over the past five years, I have also led a project on the measure of physical activity by accelerometer in the Whitehall II Study. This involves management of the data collection and analyses of the data (Sabia et al, J Am Med Dir Assoc, 2015). My longstanding interests are in methodological issues of statistical analysis in order to study aging outcomes: cubic splines, bootstrap method, longitudinal analyses with repeated data, missing data, etc. This has led to better modeling of longitudinal data, for both the exposure and the outcome. For example, in order to explore changes over time in exposure variables before an event onset, I used mixed models with a backward timescale to test for differences in trajectories of an exposure between those who will develop dementia and the others (Sabia et al, BMJ, 2017). Attrition over the course of a study is common in longitudinal data and I have shown that the impact of smoking on cognitive decline might have been underestimated previously due to higher risk of drop-out among current smokers (Sabia et al, Arch Gen Psychiatry, 2012).