Well one idea I had was this: 
Military/peace keepers/law enforcement might have particularly powerful ANCIs that use an outside power source(is this normal?). They try to prevent or redirect the worst of ANC overload symptoms with heat sinks, but the greater amount of power still basically guarantees neural degeneration. As such, people in these roles have much shorter life spans, and not just because of the potentially violent nature of their jobs. 

My other idea was a separate, isolationist colony that is ruled by an oligarchy, which systematically suppresses certain knowledge, particularly that of ANC technology. This ruling class uses ANCIs to appear as gods to the lower class.