Does the neuropsychological impairment relate to clinical symptoms and signs?
One of the few features of schizophrenia that most authors agree on is its heterogeneity. It is possible that part of the difficulty in detecting a consistent neuropsychological signature of schizophrenia (Blanchard & Neale, 1994) is that there is no such thing as schizophrenia . Syndromes or symptoms may more clearly relate to disordered patterns of information processing. Liddle & Morris (1991) conducted a seminal study in this area where they assessed a group of patients with chronic schizophrenia using a battery of neuropsychological tests allegedly sensitive to frontal lobe dysfunction. Signs and symptoms were clustered into three syndromes: psychomotor poverty, disorganisation and reality distortion. Scores for the disorganisation syndrome were associated with impairment on tests that required the subject to inhibit a well-established but inappropriate response. Ratings for the psychomotor poverty syndrome were found to be associated with slowness of mental activity. More recentl
