Narrator: This is Science Today. After Alzheimer's disease, the second most common cause of dementia in individuals under the age of 65 is a disease called frontotemporal lobar degeneration, or FTLD. Aimee Kao, a professor of neurology at the University of California, San Francisco, explains that it's a very unusual disease.
Kao: Instead of striking, for example, memory, which is what is usually affected first in Alzheimer's disease, this disease tends to affect more of the functions that are housed in the frontal and the temporal lobes of the brain. That's why it's called frontotemporal lobar degeneration. And those are cognitive processes that we might think of as sort of higher human processes. So, emotional processing, multi-tasking, language, the ability to appreciate and generate art, personality, empathy. So it affects much more, I think behavior and personality. And then in some subtypes, it also affects language.
Narrator: For Science Today, I'm Larissa Branin.