Malcolm Young, the co-founder of rock band AC/DC, has died at the age of 64, according to a statement on the group’s website. Ailing for several years with dementia, Young created the Australian heavy metal band with his brother Angus Young in 1972. He was the group’s guitar player until April 2014 when he took leave of the band. It was later announced he had been suffering with dementia, according to Rolling Stone magazine. AC/DC was known for its bold guitar riffs and declarative, howling vocals, characterized by such songs as Back in Black and Highway to Hell. “Today, it is with deep heartfelt sadness that AC/DC has to announce the passing of Malcolm Young,” a statement read on the band’s website. "With enormous dedication and commitment, he was the driving force behind the band. As a guitarist, songwriter and visionary, he was a perfectionist and a unique man," Angus Young said in a statement.