1980s rocker Jack Russell dies at 63 after dementia diagnosis. Jack, lead singer of Great White, passed away surrounded by family. The band pays tribute to his incredible voice and love for fans. Jack’s legacy in rock music will live on forever. He leaves behind his wife and son. Public memorial to be held later. Lewy Body dementia is a progressive disorder affecting cognitive, motor, and behavioural functions. Symptoms may include cognitive impairments, motor issues, visual hallucinations, and fluctuating cognition. Jack’s death follows his retirement announcement due to his diagnosis.