About 10% of all cases of dementia are classed as frontotemporal dementia. This illness tends to strike when people are in their fifties. It frequently runs in families, and like Alzheimer's disease, there is a gene which is linked to these cases. But, also like Alzheimer's, the underlying causes of the disease are unknown and there is no cure.

Whereas Alzheimer's disease typically strikes first at the memory centers in hippocampus and nearby structures, frontotemporal dementia destroys brains in the frontal lobes of the brain, which are responsible for "higher thinking," including judgment, planning and abstract reasoning. It may also damage areas in the front of the temporal lobes, disrupting social behavior and language skills.

Like Alzheimer's disease, frontotemporal dementia eventually spreads throughout the brain, causing increasing cognitive breakdown until patients require round-the-clock care.