I too noticed mood changes in my son when he started taking singulair at age 4. I dismissed it at the time because he was my first child and I didn't want to overreact. I still notice the same things that you mentioned in your post. My son too has said "I wish I were dead", and "I wish I was never born". He also, is easily angered and very moody with innapropriate reactions to things. He is now 8 and I would be interested to know if being on singulair all this time has messed with brain developement. My son is extreemly bright but emotionally he has always had problems. I don't want to blame all behavior issues on this medication but I am convinced that it has affected him emotionally.