The need for improving dementia care has driven the development of the clinical decision support system DMSS (Dementia Management and Support System). A sociotechnical approach to design and development has been applied, with an activity-centered methodology and user participation throughout the process. Prototypes have been developed based on the characteristics of clinical practice and domain knowledge, while clinical practice has been subjected to different efforts for development such as education and organizational change. A set of evidence-based clinical practice guidelines has been synthesized and integrated in DMSS to support clinical routines and reasoning processes as performed by individual health professionals in daily practice. DMSS-R provides advice, tailored to the individual and often exceptional patient case, to the user while providing guidance to the next step in the assessments and support for hypothesis generation and valuation throughout the process. This paper addresses the lessons learned and role and impact DMSS has had, and is expected to have on the clinical assessment of dementia in different clinics in Sweden, South Korea and Japan. Furthermore, it will be described in what way the development of DMSS and the development of dementia care in these three areas are interlinked. A recent evaluation study showed that the most important contribution of DMSS-R at the point of care, part from the tailored explanatory support related to a patient case, was the educational support that DMSS-R provided. This was partly manifested in a change of routines in the encounter with patients. Aspects regarding the individual health care professional’s need for a personalized support system are discussed and put in relation to the team’s need for support, and in relation to the diversity of disease manifestations in this group of patients, which enforces patient-centric assessments.