Novel technologies for early diagnosis of Alzheimer's disease (AD) will impact the way society views and deals with AD and ageing. However, such "sociocultural" impacts are hardly acknowledged in standard approaches of technology assessment. In this paper, we outline three steps to assess such broader impacts. First, conceptual analysis of the ideas underlying technological developments shows how these technologies redraw the boundary between Alzheimer's disease and normal ageing and between biological and social approaches of ageing. Second, imaginative scenarios are designed depicting different possible futures of AD diagnosis and societal ways to deal with ageing and the aged. Third, such scenarios enable deliberation on the sociocultural impact of AD diagnostic technologies among a broad set of stakeholders. An early, broad, and democratic assessment of innovations in diagnostics of AD is a valuable addition to established forms of technology assessment.