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. Author manuscript; available in PMC: 2016 Jun 1.
Published in final edited form as: Am J Psychiatry. 2015 May 18;172(6):543–552. doi: 10.1176/appi.ajp.2014.14030382

Figure 1. Association of PPM1G Methylation With Drinking Escalation (N=352) and Trait Impulsiveness (N=399) in Adolescentsa.

Figure 1

aAs shown in panel A, PPM1G methylation is positively associated with an increase in amount of daily drinking (corrected p=0.024). PPM1G methylation at age 14 predicts an increase in daily drinking between ages 14 and 16. In panel B, an increase in amount of daily drinking is positively associated with impulsiveness in 16-year-old adolescents (corrected p=0.041). In panel C, PPM1G methylation is positively associated with impulsiveness (corrected p=0.032). All graphs represent data for each individual and have linear fit lines. In panels A and B, escalation of daily drinking is measured as the difference between age 14 and age 16 on an item on amount of daily drinking from the European School Survey Project on Alcohol and Other Drugs questionnaire (on a five-level ordinal scale). In panels B and C, impulsiveness is represented by a sum score of five items (on a five-level ordinal scale) of the Substance Use Risk Profile Scale.