Actor Bruce Willis has been diagnosed with frontotemporal dementia 

family members announced in a joint Instagram post Thursday.

The diagnosis of frontotemporal dementia

A brain disorder caused by degeneration of the brain's frontal lobe,

comes nearly a year after Willis' family confirmed the movie icon,

now 67, was stepping away from acting due to an aphasia diagnosis.

A message posted on the Instagram accounts of wife Emma Heming Willis,

ex-wife Demi Moore and daughter Rumer Willis states:

Our family wanted to start by expressing our deepest gratitude for the incredible outpouring of love

support and wonderful stories we have all received since sharing Bruce’s original diagnosis