In the context of neurodegenerative diseases (NDD), many challenges emerge for the health of persons with the disease (PwD), but also the health of their caregivers, most often their spouse. Within this dyad, partners are interdependent: their stress level, distress and coping strategies influence each other. The quality of the relationship also affects each partner’s health and plays a crucial role in the adjustment to the disease. These factors underline the major need for a dyadic approach in this context.

In the field of NDDs, most of works dealing with couple dynamics focus on Alzheimer's disease (AD) and have revealed a deterioration in the dyadic adjustment, from early stages of the disease, as well as the challenge of maintaining a relational connection despite identity upheavals. Thus, promoting the quality of the relationship seems fundamental, especially since it moderates, in AD, the impact of symptoms on caregiver distress.

Nevertheless, there are several limitations to these studies and to the clinical interventions based on their results. First, despite the specific implications of each type of dyadic relationship, they are often undifferentiated. Yet, spouses are particularly vulnerable and targeting the couple relationship is then a priority. Secondly, there has been little research focusing on the dynamics of couples facing Parkinson’s disease (PD) or Huntington’s disease (HD), unlike AD. Finally, the support currently proposed to couples often lacks specificity, targeting partners separately and not considering relational processes.

The aim of this thesis is to go beyond these individual approaches and to propose a dyadic perspective on the support provided to couples facing a NDD. To this purpose, (1) a better understanding of the processes involved in the functioning of these couples facing AD, PD and HD is essential and will enable to refine existing dyadic models, which (2) will then allow the design of dyadic interventions centered on the well-being of these couples.