Further development of delta and kappa opioid drugs will join the growing body of studies addressing other targets, such as gamma-aminobutyric acid receptors and voltage-gated ion channels. These drugs will likely complete other non-pharmacological therapies, including transcranial magnetic stimulation or behavioral, cognitive therapies and group therapies considered very effective in long-term treatments (Addolorato et al., 2012; Volkow and Skolnick, 2012).