Demography has two faculty positions (professor and university lecturer) at the University of Helsinki and currently around 10 researchers are employed at the Population Research Unit by external funding from the Academy of Finland, the European Union, Finnish government, and several private research foundations. Our research is published in international scientific peer-reviewed journals including leading journals of demography and sociology of health (e.g. Demography and Social Science and Medicine), epidemiology (e.g. International Journal of Epidemiology and American Journal of Epidemiology), as well as other fields of science (e.g. Addiction and American Journal of Clinical Nutrition).

The research at the Population Research Unit has traditionally stemmed from the use of Finnish longitudinal population-based registers, which still provide invaluable information for scientific research. The unit maintains several register-based data sets designed for the analysis of different demographic and social phenomena. These data link large representative samples of individual-level records on socio-demographic characteristics with outcome data such as causes of death, hospital discharge diagnoses, medication purchases, pensions, and crime. In the recent years, other data sets with questionnaire-based information, biomedical measures, and genetic data have also become an important part of research at the PRU.

A particular long-term aim of our research is to provide novel evidence on the factors influencing current trends and causes of social differences in health and well-being. Such disparities are driven by a range of more distal socio-structural factors such as educational and labour market processes, income distribution, regional contexts, and long-term social transformations such as population ageing and family change, and more proximate individual-level factors, such as individual characteristics, behaviours, and psychosocial circumstances.

The team has developed multidimensional causal frameworks for the study of social determinants of health and used natural experiment and quasi-experimental study designs to quantify the effects of policies (alcohol tax changes), societal shocks (mass unemployment) or life-events (retirement) to make stronger causal inferences. Further, we have used family designs to disentangle the effects of social and genetic family background from the causal effects of social factors and other risk exposures to health. The latest developments include analysing how measured genetic polymorphisms interact with psychosocial factors when predicting obesity and cardio-vascular mortality. These different types of analyses contribute to our theoretical understanding of social determinants of health in pinpointing the relative importance of various causal factors and pathways leading to adverse or beneficial outcomes in health and well-being. International collaboration has also allowed us to analyse these processes in a wider context. Comparing Finland, Japan and the UK, for example, has allowed us to analyse socio-economic differences in health in three very different wealthy societies, and our collaborative twin study covering data from altogether 23 countries to analyse how societies modify the effect of genetic and environmental factors on obesity, other key human anthropometric measures, and their associations with socio-economic factors.

Research collaboration – both national and international – and researcher mobility are key factors in developing and maintaining the quality of research and doctoral training. The PRU has a wide international research network and a large part of our research is carried out and published in international collaborations with leading scholars. In the period 2012−2017, we published with foreign academics from more than 20 countries working in more than 40 research groups. Some of the most important international partnerships include University College London, London School of Economics, Erasmus Medical Centre, University of Pennsylvania, Harvard School of Public Health, University of Toyama, Osaka City University, Stockholm University, Karolinska Institutet, Oslo University College, University of Copenhagen, and Max Planck Institute for Demographic Research in Rostock. Our researchers have made both long- and short-term research visits to the universities mentioned above and the Population Research Unit has also hosted several international guest researchers and seminars. The principal investigators have also supervised and examined several doctoral dissertations in foreign universities.

In Finland we collaborate with the Department of Public Health at the Medical Faculty, University of Helsinki, the National Institute for Health and Welfare, the Finnish Institute of Occupational Health, the Finnish Centre for Pensions, the Finnish Institute for Molecular Medicine and Research, and the Research Institute of the Finnish Economy.

Since 1994 the Population Research Unit has been responsible for hosting the doctoral seminar ‘Population, Health and Living Conditions’. The principal aim of the seminar is to train leading researchers of population health and well-being through (1) rigorous instruction in the theoretical approaches, methods, and empirical analyses, and (2) incorporation of students into departmental research projects that will eventually lead into independent research work. The doctoral training is closely intertwined with the PRU’s general focus and research projects, and the seminar is run in collaboration with medical sociologists (Faculty of Medicine) and social psychologists (Faculty of Social Sciences).

The doctoral training is based on a twice-a-month research seminar and courses on theory and methods of demography and social epidemiology. The seminar also organises teaching together with the Doctoral Programme in Social Sciences. Training is international with foreign visitors and teachers participating in the seminar work. An annual seminar with our Swedish partners (Department of Public Health Sciences, Stockholm University) has continued for over fifteen years. In addition, research training with Scottish colleagues (Medical Research Council/Social and Public Health Sciences Unit, University of Glasgow) has been frequent for more than twenty years, with the more recent joint doctoral seminars with the University College London, University of Manchester, and Örebro University. Doctoral students also often visit these collaborating universities.

We foster societal interaction by collaborating with the Finnish Ministry of Health and Social Affairs, the National Institute for Health and Welfare (THL), the Finnish Institute of Occupational Health (TTL), Statistics Finland, the Finnish Centre for Pensions (ETK), the Research Institute of the Finnish Economy (ETLA) and the Social Insurance Institution (Kela). Although the majority of our research is published in international scientific journals, our researchers have also actively published in Finnish-language journals and books with a broader readership. The results published in scientific journals are also disseminated through press releases and social media, and our researchers are frequently approached by the media, with key results receiving also international media coverage.

Our scientific results have improved the understanding on the social determinants of health in the Finnish society as well as in a wider international context. For example, we have demonstrated the large social differentials in mortality and health in Finland first increasing in the 21st century, and then decreasing mostly due to changes in alcohol-related mortality. Importantly, our analyses of the alcohol tax reduction in Finland showed an increase in alcohol-related mortality in the socially disadvantaged groups. Our comparative evidence have further demonstrated that the Nordic welfare system has not been able to produce smaller social differentials than elsewhere in Europe.

We have actively participated in governmental working groups that aim to improve the data base for studying and monitoring social determinants of health, and strengthen the links between research and practice. Our research has been used to set targets for the reduction of socioeconomic inequalities in health and mortality in the national action plan and we have attracted funding for policy relevant research topics such as national and global health promotion, public health, the demand and funding for long-term care, and the means for reduction of social inequalities in Europe. Most of our research provides evidence for prevention, health promotion, and improving the level and equal distribution of health.