Bruce Willis has frontotemporal dementia. What is FTD?

Bruce Willis' family has announced that he has been diagnosed with frontotemporal dementia.

The announcement Thursday (Feb 16) came about a year after his family said that Willis would step away from acting after being diagnosed with aphasia, a brain disorder that leads to speaking, reading and writing problems.

Here's some details on the condition:

WHAT IS FRONTOTEMPORAL DEMENTIA?

There are different types of dementia, and the frontotemporal form affects regions in the front and sides of the brain. Because it causes problems with behaviour and language, aphasia can be a symptom.

It's caused by damage to neurons, the brain's information carriers, but the underlying reasons for a particular case are often unclear. People with a family history of the condition are more likely to develop it. It's rare and tends to happen at a younger age than other forms of dementia, between ages 45 and 65.

The terms frontotemporal disorders and frontotemporal dementia are sometimes shortened to FTD.

WHAT ARE OTHER SYMPTOMS OF FTD?

Symptoms can include emotional problems and physical difficulties, such as trouble walking. Symptoms tend to worsen over time, though progression varies by person.

The statement from the actor's family said communication problems "are just one symptom of the disease Bruce faces."

CAN FTD BE TREATED?

There are no treatments to slow or stop the disease, but some interventions can help manage symptoms.

Some patients receive antidepressants or drugs for Parkinson's, which has some overlapping symptoms with frontotemporal dementia. Many also work with speech therapists to manage communication difficulties and physical therapists to try to improve movement.

People with the condition are more likely to have complications from things like falls, injuries or infections. The average life expectancy after symptoms emerge is seven to 13 years, according to researchers.