Time of pubertal onset, testosterone levels and intelligence in 47,XXY males

This study examined the relations between verbal and performance IQs, time of pubertal onset and testosterone levels from 13 to 16 years of age in a sample of 30 males with a supernumerary X chromosome. The findings indicated that verbal IQs measured prior to puberty, during puberty and at mid-adolescence were strongly related to relatively early pubertal onset and testosterone levels. Performance IQs had little or no relationship with the same variables. The results are discussed in terms of several different psychobiological models.