Attentional and neurocognitive characteristics of high-risk offspring of parents with schizophrenia compared with DSM-IV attention deficit hyperactivity disorder children.

Offspring of individuals with schizophrenia are at increased baseline risk for a range of early mental disorders. Studies investigating the premorbid characteristics of individuals with schizophrenia indicate that they suffer from social, behavioral, attentional and neurocognitive impairments, often resembling attention deficit hyperactivity disorder (ADHD). In this study, we compared the executive functioning and general intelligence among three groups: (i) children and adolescents with DSM-IV ADHD (n=41), (ii) "high-risk" (HR) offspring of parents with DSM-IV schizophrenia, and (iii) normal comparison subjects (n=35). Our results indicated that both HR and ADHD groups had lower Verbal IQ scores. ADHD cases had significantly lower percent correct and total errors in Wisconsin Cart Sorting Test when compared with normal comparison subjects. The HR cases also had lower Performance IQ scores as well as worse abstraction--flexibility and comprehension performance. The HR group was further stratified with (HR-A) and without (HR-NA) comorbid ADHD, and HR-A subjects were significantly noted to be more impaired on most tests. The overall worse performance of HR offspring was attributable to significantly lower performance among the HR-A youth. Further, our results suggested that the most profoundly impaired HR subjects were in fact children and adolescents who also met criteria for ADHD. Future studies with broader neuropsychological test batteries are necessary to investigate the differences and similarities between ADHD and the HR-A subgroup.