A small number of scientists have claimed that ordinary spanking does no harm. Other scientists say that "over 100" studies have shown that spanking can harm children. They say that spanking harms children's mental growth. They also say that children who are spanked grow up to have more mental illnesses. They say that no study has shown any good to come from spanking. Scientists at the University of Manitoba in Canada found that children who were hit even "sometimes" suffered more mental illnesses when they grew up. They could have different kinds of mental illnesses: long-lasting sad or discouraged feelings and a loss of pleasure and interest in life (depression), a lot of fear and worry (anxiety), racing thoughts that are hard to control and acting without thinking (mania), or a need to take drugs or alcohol to feel well (drug and alcohol abuse). Other scientists have discovered that spanking children often can make their brains grow less than they should. These children end up less able to think clearly. They also try to hurt others more.