These symptoms can show up as increased stress, mood changes, trouble focusing, or feeling overwhelmed more often. Because nicotine affects the brain's reward and stress systems, it can make it harder to Nicotine, e cigarettes, cannabis: All pose different risks and all can be hard to stop UCLA Health Rsistance d'une cigarette lectronique : Qu'est ce que c'est ? Tout savoir sur les rsistances i liquo