In the case of non-significant interaction, the primary analysis will be based on the ANCOVA model with main effects of treatments and adjusting for age. Since there are two treatments under investigation, the primary analysis will use the Bonferroni correction, i.e. will set alpha level of 0.025 (two-sided) to determine statistical significance. The significance of the main effect of each treatment will be assessed by t-tests in the ANCOVA model. The aim of the primary analysis is to determine whether each treatment is superior to placebo, and if both hypotheses hold, the double treatment therapy will be most effective under the additive effect assumption of the ANCOVA model. The ANCOVA model compares all subjects who receive that treatment with all subjects who do not, irrespective of whether they receive the other treatment, after adjusting for the other treatment and age of subject, and is more powerful in finding individual treatment effects in the study.