The prerequisite for working across multiple datasets is interoperability with regard to their features. This aspects includes the availability of features, the same naming conventions and comparable representations. While we explored the representations of important features in the "Cohorts" section, here we focus on naming conventions and to conceptually map similar features to their corresponding counterparts in other datasets. Disclaimer: This work is not a complete mapping of all features available in these cohorts. It serves as an overview on the current state of dataset interoperability and showcases that there is no common data model for dementia datasets in use. This hinders data-driven approaches across cohorts substantially.