1,000 participants from New Zealand were used to establish a testing group for this research. They were all born between 1972 and 1973 and then tested periodically throughout their growing years for cognitive impairments characteristic of schizophrenic patients. It was shown that the percentage of patients considered schizophrenic in their adult years had related developmental difficulties that was seen as early as age 7. These difficulties consist of a child's visual learning, working memory, processing speed, attention span, verbal reasoning and the solving of visual-spatial problems.
To facilitate this research, three fundamental yet unanswered questions within the scope of study are acknowledged: What is the developmental course of schizophrenia prior to its onset? Do different cognitive characteristics follow similar or different developmental paths? And are there developmental difficulties specific to schizophrenia?
Testing for these disabilities began at age 3 and were continued until age 13 in 2 year intervals; a testing methodology apart of the Dunedin Multidisciplinary Health and Development Study. Furthermore, it was noticed that between the ages of 7 and 13, a loss in .17 and .26 of mental age was apparent in children who would later become diagnosed with schizophrenia.
By the age of 32, it was shown that 2.5 percent of the participants monitored met the diagnostic criteria of schizophrenia and 1 percent met the formal criteria. Only the participants who met the formal criteria were hospitalized and put on antipsychotic medication. Their conclusions consisted of two findings evident between childhood and early adolescence of the children who grew up to develop schizophrenia: Upon entering primary school, they struggled with verbal reasoning and as they aged, lagged behind their peers in working memory, attention, and processing.
Now what does all this mean? Schizophrenia is not an all-of-the-sudden occurrence, but related to a child's development. Children who developed schizophrenia lagged behind in school compared to their peers and continued to do so. Initially their verbal skills are poor and as they age, continue to develop other hindrances in learning. Their minds did grow, but their abilities to make sense of the world forced them into social isolation/delusion. This study offers a unique view not so much into why schizophrenia occurs but what traits are similar in those diagnosed. Future research will focus on the causes of this disease based on these stages of human development.