Associations between adolescent cannabis use and neuropsychological decline: a longitudinal co‐twin control study

• DOI: 10.1111/add.13946
• Publication Date: 2017-07-22T11:26:35Z
• Authors: Madeline H. Meier; Avshalom Caspi; Andrea Danese; Helen L. Fisher; Renate Houts; Louise Arseneault; Terrie E. Moffitt
• Keywords: Longitudinal Study; Cannabis Dependence

This study tested whether adolescents who used cannabis or met criteria for dependence showed neuropsychological impairment prior to initiation and decline from before after initiation.A longitudinal co-twin control study.Participants were 1989 twins the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative birth cohort of born in England Wales 1994 1995.Frequency use assessed at age 18. Intelligence quotient (IQ) was obtained ages 5, 12 Executive functions 18.Compared with did not cannabis, had lower IQ childhood 18, but there little evidence that associated 12-18. For example, 18 scores 5.61 (t = -3.11, P 0.002) 7.34 points -5.27, < 0.001) than without dependence, show greater 12-18 -1.27, 0.20). Moreover, poorer executive these associations generally apparent within twin pairs. more frequently their performed similarly on five six function tests (Ps > 0.10). The one exception worse working memory test (Spatial Span reversed; β -0.07, 0.036).Short-term adolescence does appear cause impair functions, even when reaches level dependence. Family background factors explain why adolescent users perform tests.