The "big data" paradigm has gained a lot of attention recently, in particular in those areas of biomedicine where we face clear unmet medical needs. Coined as a new paradigm for complex problem solving, big data approaches seem to open promising perspectives in particular for a better understanding of complex diseases such as Alzheimer's disease and other dementias. In this commentary, we will provide a brief overview on big data principles and the potential they may bring to dementia research, and - most importantly - we will do a reality check in order to provide an answer to the question of whether dementia research is ready for big data approaches.