Background: Touchscreen technology with easy-to-use applications (apps) is increasingly recognized to have potential to support activities and functional ability of people with dementia. A growing number of mobile apps are developed and assessed to be dementia- friendly. However, the unique potential of using technologybased data-collection to document usability and applicability of an app at a more specific level, and to optimize product development, is rarely utilized. This study aims to create a mobile app which can support cognitive functions and enhance level of independent activities in daily living of people with early stage dementia. The app is created by combining participatory design and analysis of detailed data-logs, collected from real life use of the app, to optimize the development and implementation of the app. Methods: A mobile app (the ReACT[1]app) was developed through an iterative innovation process, where people with early stage dementia and caregivers took part in outlining and designing the functionalities and user-interface, and testing and adapting the app. A total of 30 dyads have been involved in this process. The ReACT app is a multi-functionality app with a user-interface which is optimized for people with early stage dementia. The app integrates many of the tools which the target group strive to use in their daily effort to keep up independent activities, e.g. calendar, reminders, diary notes, to-do lists etc. The app is also designed to be adaptable, to comply with individual needs and variation in technology skills. In addition, the app is designed to provide continues data-logs, which gives researchers unique detailed information on the actual use of specific functionalities of the app. A proof-ofconcept study is conducted, where data is collected from 100 people with dementia. Results: The study is ongoing. Results will be available in May 2017. Conclusions: This study will give insight into the potential of combining participatory design and technology- based data-collection to optimize the development of technology for people with dementia. The continuous data-collection will also facilitate new perspectives on telemedicine as part of the future development of the app. [1] ReACT- Rehabilitation in Alzheimer's disease using Cognitive Support Technology.