Symptoms of schizophrenia often appear soon after puberty, when the brain is undergoing significant maturational changes. Some investigators believe that the disease process of schizophrenia begins prenatally, lies dormant until puberty, and then causes a period of neural degeneration that causes the symptoms to emerge. However, reanalysis of the data from the later Finnish study, on older children (14 to 16) in a changed school system, using narrower diagnostic criteria and with less cases but more controls, did not support a significant difference on sports and handicraft performance. However, another study found that unusual motor coordination scores at 7 years of age were associated in adulthood with both those with schizophrenia and their unaffected siblings, while unusual movements at ages 4 and 7 predicted adult schizophrenia but not unaffected sibling status.