Figure 2From: Zinc sulfate as an adjunct to methylphenidate for the treatment of attention deficit hyperactivity disorder in children: A double blind and randomized trial [ISRCTN64132371]Mean ± SEM scores of two groups of children on the Teacher ADHD Rating Scale. ns = non-significant, *** = P < 0.001. The horizontal symbols (***) were used to express statistical significance versus their respective baseline value and the vertical symbols are for between group comparisons.Back to article page