Adult Lifelines participants who were not able to independently fill in the baseline questionnaires, for example due to mental or physical problems, could choose to undergo a short interview on the location of 1A visit 1.
Elderly participants who scored less than 26 points on the MMSE during 1A visit 1 also underwent the proxy interview rather than the questionnaires.
In total, ~3500 participants underwent the proxy.
The proxy interview was performed between a participant and the research assistant on the location of 1A Visit 1. The assistant stated the questions slowly and clearly, and filled in the answers on a computer screen. If the participant had difficulty answering, a family member or caretaker - if present - was allowed to help the participants with the answers.
The proxy interview contained variables in the following sections and subsections: