To the Editor: Dr Lynskey and colleagues1 concluded that early cannabis use is associated with an increased risk for later use and dependence on other drugs. Although the authors used both monozygotic and dizygotic same-sex twins to ensure similar environmental influences, we are concerned that the sample may not be representative of the population, as there was an unusually high prevalence of alcohol dependence in both cannabis users and their co-twin controls compared with that of the general population.2 - 3 Early cannabis users in the study of Lynskey et al had a 42.8% prevalence of alcohol dependence, whereas their co-twin controls had a prevalence of 29.6%. By contrast, the prevalence of alcohol abuse among Australian adults has been reported to be about 6.5%,2 ,4 with a 4.1% prevalence of alcohol dependence.2 About 8.3% of Australians aged 14 years and older report daily alcohol use.5 Similarly, the prevalence of alcohol dependence in the United States has been estimated to be about 6% of men and 2% of women.3
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
Instructions
Comments are moderated and will appear on the site at the discretion of the Journal of American Medical Association editors. Comments should not exceed 500 words of text and 10 references.
Do not submit personal medical questions or information that could identify a specific patient, questions about a particular case, or general inquiries to an author. Only content that has not been published, posted, or submitted elsewhere should be submitted. By submitting this Comment, you and any coauthors transfer copyright to the journal if your Comment is posted.
* = Required Field
Disclosure of Any Conflicts of Interest* Indicate all relevant conflicts of interest of each author below, including all relevant financial interests, activities, and relationships within the past 3 years including, but not limited to, employment, affiliation, grants or funding, consultancies, honoraria or payment, speakers’ bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued. If all authors have none, check "No potential conflicts or relevant financial interests" in the box below. Please also indicate any funding received in support of this work. The information will be posted with your response.
Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more
Subscribe for full-text access to content from 1998 forward and a host of useful features
Activate your current subscription (AMA members and current subscribers)
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Customize your page view by dragging & repositioning the boxes below.
and access these and other features:
Register Now
Enter your username and email address. We'll send you a reminder to the email address on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.