DURHAM, N.C. Years before adults develop schizophrenia, there is a pattern of cognitive difficulties they experience as children, including problems with verbal reasoning, working memory, attention and processing speed.
Drawing on a long-term study of more than 1,000 New Zealanders born from 1972 to 1973, a team led by Duke researchers has found a consistent pattern of developmental difficulties that first appeared when adult study subjects with schizophrenia were 7 years old.
"The proportion of kids who don't score well on these tests is big, and the number of kids who develop schizophrenia is tiny," said study co-author Terrie E. Moffitt, the Knut Schmidt Nielsen professor of psychology and neuroscience at Duke. But now that the study subjects are in their late 30s and mental illnesses have been identified, "we looked backwards to understand more about how schizophrenia may develop."
By age 32, 1 percent of the study participants met the formal criteria for schizophrenia and had been hospitalized and put on antipsychotic medication. Another 2.5 percent met the diagnostic criteria for the disorder, but hadn't received treatment.
Knowing what they know now, the researchers were able to track the progress of these cognitive deficits as the subjects went through testing at ages 3, 5, 7, 9, 11 and 13 as part of the Dunedin Multidisciplinary Health and Development Study.
"These kids are lagging behind to begin with and they continue to fall behind," said study co-author Richard Keefe, director of Duke's Schizophrenia Research Group. Their verbal skills are initially poor, and then they develop other problems along the way, including difficulties with memory and verbal processing, key factors in learning.
For each year between the ages of 7 and 13, the children who later received a diagnosis of schizophrenia lost between 0.17 and 0.26 years in mental age when compared with the other children.
|Contact: Karl Leif Bates|