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July 16, 2003

Early Exposure to Marijuana and Risk of Later Drug Use—Reply

Author Affiliations

Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.

JAMA. 2003;290(3):331-332. doi:10.1001/jama.290.3.331

In Reply: Dr Anand raises 2 issues in epidemiological research on the etiology of substance abuse.

First, he suggests that the models tested by Lynskey et al1 were misspecified. Assuming that administration of opiates or other drugs to mothers at the time of delivery does increase the risk of drug addiction in offspring, does the omission of this factor in the analysis of Lynskey et al affect their conclusions in any way? I agree with Anand that the conclusions of Lynskey et al are not invalidated by the lack of attention to perinatal exposure to obstetric pain medication at the time of delivery. Both twins were similarly exposed to the putative perinatal causal factor. In a twin design, perinatal experiences are part of the shared influences that are held constant for subjects.