Frontotemporal dementias are less well known than Alzheimer's disease but account for over half of the cases of dementia in people younger than 65 years. The last few years have witnessed rapid developments in the understanding of this group of diseases, particularly in terms of their genetic underpinnings and imaging characteristics. This symposium convenes leading scientists with expertise in trontotemporal dementias to discuss the current understanding of these diseases and ongoing research to discover effective therapies.