Neuropsychological profiles in schizophrenia: Paranoid versus undifferentiated distinctions

Research on schizophrenia has searched for subtype-specific cognitive dysfunction to elucidate the neurodevelopmental underpinnings of the disorder. The neuropsychological distinctions between 21 paranoid and 15 undifferentiated schizophrenics were studied. The paranoid group had significantly better Verbal IQ, executive functioning on the Wisconsin Card Sorting Test, and memory for spoken language on the Sentence Repetition Test compared to undifferentiated schizophrenics. While the paranoid subtype showed trends toward better performance on a wide variety of tasks, both subtypes showed impairments on tasks requiring continuous auditory attention and fine motor speed and coordination. Despite the paranoid subjects' more intact verbal skills, both groups showed significant deficits in verbal learning on the Rey Auditory Verbal Learning Test. This suggests that temporal-hippocampal system dysfunction may be a common denominator in both schizophrenic subtypes. These findings were not accounted for by subtype differences in the level of education, depression or severity of illness.