Lifelines variables are organized per theme in 13 main sections and ~230 subsections.
The 13 sections are:

1. Children & adolescents
2. Demographics
3. Diseases & Symptoms
4. Elderly (variables that were specifically collected in participants aged 65+ years old)
5. Family health
6. Lifestyle & environment
7. Medical treatment
8. Mental health
9. Nutrition
10. Physical state
11. Reproduction & development
12. Wellbeing & subjective health
13. Secondary & linked variables

Note that some subsections could fall under more than one section (i.e., “alcohol use” could be seen as a subsection of “lifestyle” or of “nutrition”, and “mental illness” could fall under “diseases & symptoms” or “mental health”). Similarly, individual variables may fit in more than one subsection. Lifelines always asigns a primary section and subsection to a variable, but may asign a secondary section and/or subsection to facilitate the findability of the variable in the online data catalogue.