Abstract. The human-computer interaction community has largely defended the use of an iterative process in which the users and stakeholders participate in all activities throughout the development of an interactive system. This work can become challenging when users have an evolving profiles in degenerative diseases (e.g. Parkinson’s and Alzheimer’s). The needs of the users at the start of the process may no longer be the same at the end when the system is validated. As consequence, it is important to integrate users in different stages of the disease in the whole process. The involvement of stakeholders (such as healthcare professionals, family members and caregivers) is also crucial for the better understanding of the user’s needs and their evolving profile. This article presents how we deal with the evolving user profile in the development of a communication aid software for people with Parkinson’s disease. To that end, we have customized the ISO 9241-210 human-centred process with a series of human-computer studies from a broad to a more focused goal. It presents this process and the complementary studies carried out with 97 people with Parkinson’s disease, 5 relatives/caregivers and 5 health professionals. In light of the insights gained from this experience, we have formulated several recommendations for human-centred design in the context of a user with an evolving profile. These recommendations outline a human-centred approach to guide the development of software applications for users with evolving profiles.