VOA慢速英语:Drink and Smoke Go 'Hand-in-Hand,' Scientists Say

addiction – n. a strong and harmful need to regularly have something (such as a drug) or do something (such as gamble) : addictive – adj.

vice versa – adv. used to say that the opposite of a statement is also true 

stimulate – v. to make (something) more active : to cause or encourage (something) to happen or develop

reward center – n. any of multiple different regions of the brain which have been involved in generating satisfaction : also called the “pleasure center” (http://psychologydictionary.org/pleasure-center/)

cancel out – phrasal verb to cause (something) to end or no longer produce a certain effect : to stop (something) from being effective or valid