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Familial factors may not explain the effect of moderate‐to‐heavy cannabis use on cognitive functioning in adolescents: a sibling‐comparison study
Author(s) -
Ellingson Jarrod M.,
Ross J. Megan,
Winiger Evan,
Stallings Michael C.,
Corley Robin P.,
Friedman Naomi P.,
Hewitt John K.,
Tapert Susan F.,
Brown Sandra A.,
Wall Tamara L.,
Hopfer Christian J.
Publication year - 2021
Publication title -
addiction
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.424
H-Index - 193
eISSN - 1360-0443
pISSN - 0965-2140
DOI - 10.1111/add.15207
Subject(s) - cannabis , sibling , neurocognitive , psychology , cognition , clinical psychology , observational study , psychiatry , medicine , developmental psychology , pathology
Aims To examine whether moderate adolescent cannabis use has neurocognitive effects that are unexplained by familial confounds, which prior family‐controlled studies may not have identified. Design A quasi‐experimental, sibling‐comparison design was applied to a prospective, observational study of adolescents with moderate cannabis use. Participants were recruited from 2001 to 2006 (mean age = 17 years). A second wave of data was collected from 2008 to 2013 (mean age = 24 years). Setting Two US metropolitan communities. Participants A total of 1192 adolescents from 596 families participated in this study. Participants were primarily male (64%) and racially and ethnically diverse (non‐Hispanic white = 45%). A sibling in each family was a clinical proband identified due to delinquent behaviors. Whereas prior family‐controlled studies have used samples of primarily infrequent cannabis users (mean = 1–2 days/month), participants here endorsed levels of cannabis use comparable to findings from epidemiological cohort studies (mean = 7–9 days/month). Measurements Semi‐structured clinical interviews assessed drug use, and a neuropsychological battery assessed cognitive abilities. Covariates included age at assessment, gender and alcohol use. Findings After correcting for multiple testing, a greater frequency and earlier onset of regular cannabis use were associated with poorer cognitive performance, specifically on tests of verbal memory. Further, after accounting for familial factors shared by siblings and alcohol use, poorer verbal memory performance was still associated with greater life‐time frequency of cannabis use at wave 1 [ b = −0.007 (−0.002, −0.012), adjusted P = 0.036]; earlier cannabis use at wave 2 [ b = − 0.12 (−0.05, −0.19), adjusted P = 0.006; b = − 0.14 (−0.06, −0.23), adjusted P = 0.006]; and greater frequency of past 6 months use at wave 2 [ b = −0.02 (−0.01, −0.03), adjusted P = 0.002; b = −0.02 (−0.01, −0.03), adjusted P = 0.008]. Conclusions Moderate adolescent cannabis use may have adverse effects on cognitive functioning, specifically verbal memory, that cannot be explained by familial factors.