Submitted for Publication: September 27, 2012; final revision received January 25, 2013; accepted January 25, 2013.
Published Online: August 21, 2013. doi:10.1001/jamapsychiatry.2013.258.
Acquisition of data: Iacono, McGue.
Analysis and interpretation of data: Hicks, Foster, McGue.
Drafting of the manuscript: Hicks.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Hicks, Foster, McGue.
Obtained funding: Iacono, McGue.
Administrative, technical, or material support: McGue.
Study supervision: McGue.
Conflict of Interest Disclosures: None reported.
Funding/Support: This work was supported in part by grants U01 DA024417 (Iacono), R01 DA005147 (Iacono), R01 AA009367 (McGue), R01 AA011886 (McGue), R01 MH066140 (McGue), and K01 DA025868 (Hicks) from the US Public Health Service.