Why might researchers exclude individuals in the generativity vs. stagnation age range from a schizophrenia study?

The reasoning behind excluding individuals in the generativity vs. stagnation age range from a schizophrenia study is that they often exceed the age of initial symptom onset for the disorder. Schizophrenia typically manifests in late adolescence to early adulthood, with the majority of patients experiencing their first psychotic episode in their late teens or early twenties. Individuals who fall into the generativity vs. stagnation stage, which usually ranges from around 40 to 65 years of age according to Erik Erikson's psychosocial development theory, are frequently beyond this age range.

By excluding this demographic, researchers can focus more accurately on the population that is most relevant to the onset and treatment of schizophrenia, ensuring a clearer understanding of the disorder in its early stages. This exclusion helps to maintain the study's validity and relevance by minimizing variations that do not pertain directly to the typical developmental trajectory of schizophrenia.