TY - JOUR
T1 - A cotwin-control analysis of drug use and abuse/dependence risk associated with early-onset cannabis use
AU - Grant, Julia D.
AU - Lynskey, Michael T.
AU - Scherrer, Jeffrey F.
AU - Agrawal, Arpana
AU - Heath, Andrew C.
AU - Bucholz, Kathleen K.
N1 - Funding Information:
This study was supported by the Department of Veterans Affairs Health Services Research and Development Service and the Cooperative Studies Program (Study 992) and by NIH grants DA014632 , DA014363 , DA018660, DA018267, AA007728, and AA011998 .
PY - 2010/1
Y1 - 2010/1
N2 - We assessed whether, after controlling for genetic and shared environmental influences, early cannabis use remains a significant predictor of other drug use, abuse, and dependence, and whether the risk for early-users is greater than that for later cannabis users. Data from a 1992 telephone diagnostic interview of 8169 male twins (M = 42.0 years at interview) who served in the U.S. military during the Vietnam-era were used to identify a subsample of 293 monozygotic (MZ) and dizygotic (DZ) twin pairs discordant for early cannabis use (before age 18). Using cotwin-control analyses, outcomes assessed were: lifetime illegal drug use (stimulant/cocaine, sedative, opiate, and hallucinogen/PCP), lifetime DSM-III-R illegal drug abuse/dependence, and lifetime DSM-III-R alcohol dependence. After controlling for covariates, early cannabis users were at greater risk than their later/never-using cotwins for 8 of 9 substance-related comparisons, including: using other illegal drugs (ORs: 2.71-4.09), having illegal drug abuse/dependence (ORs: 2.02-2.13), and developing alcohol dependence (OR = 2.36). When analyses were limited to pairs in which the cotwin used cannabis later, early and later-users only differed significantly on sedative, opiate, and hallucinogen use. After familial influences on early cannabis use were controlled for, cannabis use-regardless of the age of initiation-still conferred increased risk of other illegal drug use, drug abuse/dependence, and alcohol dependence. In contrast to previous research, there is limited evidence for increased risk associated with early-onset use in this sample of Vietnam-era veterans.
AB - We assessed whether, after controlling for genetic and shared environmental influences, early cannabis use remains a significant predictor of other drug use, abuse, and dependence, and whether the risk for early-users is greater than that for later cannabis users. Data from a 1992 telephone diagnostic interview of 8169 male twins (M = 42.0 years at interview) who served in the U.S. military during the Vietnam-era were used to identify a subsample of 293 monozygotic (MZ) and dizygotic (DZ) twin pairs discordant for early cannabis use (before age 18). Using cotwin-control analyses, outcomes assessed were: lifetime illegal drug use (stimulant/cocaine, sedative, opiate, and hallucinogen/PCP), lifetime DSM-III-R illegal drug abuse/dependence, and lifetime DSM-III-R alcohol dependence. After controlling for covariates, early cannabis users were at greater risk than their later/never-using cotwins for 8 of 9 substance-related comparisons, including: using other illegal drugs (ORs: 2.71-4.09), having illegal drug abuse/dependence (ORs: 2.02-2.13), and developing alcohol dependence (OR = 2.36). When analyses were limited to pairs in which the cotwin used cannabis later, early and later-users only differed significantly on sedative, opiate, and hallucinogen use. After familial influences on early cannabis use were controlled for, cannabis use-regardless of the age of initiation-still conferred increased risk of other illegal drug use, drug abuse/dependence, and alcohol dependence. In contrast to previous research, there is limited evidence for increased risk associated with early-onset use in this sample of Vietnam-era veterans.
KW - Alcohol dependence
KW - Cotwin-control
KW - Drug abuse/dependence
KW - Early cannabis use
UR - http://www.scopus.com/inward/record.url?scp=70349998188&partnerID=8YFLogxK
U2 - 10.1016/j.addbeh.2009.08.006
DO - 10.1016/j.addbeh.2009.08.006
M3 - Article
C2 - 19717242
AN - SCOPUS:70349998188
SN - 0306-4603
VL - 35
SP - 35
EP - 41
JO - Addictive Behaviors
JF - Addictive Behaviors
IS - 1
ER -