For the entire sample , there were no differences in symptom trajectories between study arms ; mean differences in change scores at 12 months were -0.14 ( 95 % confidence interval -0.34 to 0.07 ) for inattention ; -0.13 ( -0.31 to 0.05 ) for hyperactivity/impulsivity ; -0.09 ( -0.28 to 0.11 ) for oppositionality ; and 3.30 ( -1.23 to 7.82 ) for social skills .