Simulated shared and supported decision making for amyloid immunotherapy in Alzheimer's disease: A bicentric study

Lecanemab, the first anti-amyloid therapy approved by the European Medicines Agency, has demonstrated a statistically and clinically significant but moderate slowing of decline in early Alzheimer's disease (AD). In contrast, its long-term impact on the disease course is not formally established. Any benefit, therefore, needs to be carefully weighed against its adverse effects and practical constraints, which must be discussed with patients and caregivers within a shared decision-making process (SMD). However, applying SDM in this context is challenging due to treatment complexity, cognitive impairment and the involvement of care partners. Supported decision-making, which aims to assist individuals with decisional limitations in participating in important choices, has been promoted as a relevant approach. In this bicentric study conducted in France, we evaluated a simulated supported decision-making process in 25 patients with early AD who were eligible for lecanemab and faced the decision to choose anti-amyloid immunotherapy. We created a written decision aid using a consensus-based method to provide clear, accurate, and scientifically validated information to patients and care partners. After a one-week reflection period, both patients and care partners demonstrated a good overall understanding of the information provided, though care partners showed higher levels of comprehension and retention. The treatment was considered acceptable by most patients and their care partners. While patients ultimately remain the decision-makers, these findings highlight the central role of care partners in strengthening supported decision-making, notably through frameworks such as the French "trusted person" model.