Associations between Adolescent Cannabis Use and Neuropsychological Decline : A Longitudinal Co-Twin Control Study Madeline H. Meier, Avshalom Caspi, Andrea Danese, Helen L. Fisher, Renate Houts, Louise Arseneault, & Terrie E. Moffitt Addiction. 2018, 113, (2), 257-265. doi: 10.1111/add.13946.   Abstract Aims : This study tested whether adolescents who used cannabis or met criteria for cannabis dependence showed neuropsychological impairment prior to cannabis initiation and neuropsychological decline from before to after cannabis initiation. Design : A longitudinal co-twin control study. Setting and Participants : Participants were 1,989 twins from the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative birth cohort of twins born in England and Wales [...]