Birth order, family size, and schizophrenic symptoms

We examined the statistical relationships of position in the birth order and number of siblings to symptoms relevant for diagnosing schizophrenia and to various socioeconomic and socioanamnestic variables in a Canadian sample of 107 schizophrenics diagnosed using the DSM-III criteria. Using the criterion of statistical significance of p < 0l (2-tailed), there were only three significant relationships, all of which were weak (r < 35), and none of which involved birth-order. Those patients with more siblings less often reported ideas of reference but more frequently reported problems with an excessively slow flow of thoughts and problems concentrating and they also responded better to fluphenazine treatment.