The Norwegian Institute of Public Health twin program of research: an update.

The population-based twin program of research at the Norwegian Institute of Public Health (NIPH) was begun in 1992. It consists of a number of questionnaire and clinical interview projects exploring a broad array of mental and physical health outcomes. This article provides a brief update summarizing our research activities, some research highlights, new developments and potentials for further developing the program of twin research. In the most recent years a large effort has concentrated on completing a mental health interview study of Axis I psychiatric and substance use disorders and Axis II personality disorders. Although still in the early planning phases, one of the most significant developments is that an agreement is now in place to centralize the Norwegian twin data into a national Norwegian Twin Registry. This new registry will include twin cohorts born from 1905 onwards. Other resources for building twin projects are described. Nationally, there is great potential for linking the NIPH twin data with other health registries and with information in a number of Norway's large population-based biobank studies. Internationally, platforms such as those developed within GenomEUtwin, for data standards and data sharing and access are greatly facilitating international collaborations in twin research.