Malcolm Young, guitarist and co-founder of the legendary rock group AC/DC, has died at the age of 64, according to a Facebook post by the group.

Young had been suffering with dementia for the past few years.

The illness forced his retirement from the band that he founded with his brother, Angus Young, in 1973, according to Rolling Stone.

The group’s surviving members called Young the driving force behind AC/DC, due to his dedication and commitment.

Flashback: AC/DC’s last show with guitarist Malcolm Young https://t.co/P9aZnx9XTv

— Rolling Stone (@RollingStone) November 18, 2017

.@acdc co-founder Malcolm Young dead at 64 https://t.co/4Gx4ymT7cw

— Fox News (@FoxNews) November 18, 2017