Corporal punishment like spanking can make kids more aggressive and antisocial, and cause depression and substance abuse, changes in the brain, and developmental problems, according to a study in the Canadian Medical Association Journal. The researchers examined 20 years of previous studies and found that none of those studies found any positive effects of spanking. Physical punishment of children is banned in 32 countries. The researchers hope that in light of their findings, doctors will discourage parents from spanking, and  more countries will change child safety laws.