Cocaine and heroin abuse
 Heroin does not cause withdrawal symptoms. 
(ROOT (NP (NP (NN Cocaine)) (CC and) (NP (NN heroin) (NN abuse))))
(ROOT (S (NP (NNP Heroin)) (VP (VBZ does) (RB not) (VP (VB cause) (NP (NN withdrawal) (NNS symptoms)))) (. .)))
( ( Cocaine and ) ( heroin abuse ) )
( Heroin ( ( ( does not ) ( cause ( withdrawal symptoms ) ) ) . ) )