Cocaine and heroin abuse
 Heroin is an opiate. 
(ROOT (NP (NP (NN Cocaine)) (CC and) (NP (NN heroin) (NN abuse))))
(ROOT (S (NP (NNP Heroin)) (VP (VBZ is) (NP (DT an) (NN opiate))) (. .)))
( ( Cocaine and ) ( heroin abuse ) )
( Heroin ( ( is ( an opiate ) ) . ) )