Former presidential adviser and political commentator David Gergen died at age 83 from complications caused by Lewy body dementia on Thursday.

David Gergen served as a presidential adviser to four presidents of both parties and was a longtime CNN political analyst.

David Gergen, a former political analyst and consultant to four American presidents, has died. He was 83. His son, Christopher, confirmed to the New York Times that Gergen died of Lewy body dementia in his retirement community.