Objective: To examine the independent contribution of executive versus semantic function to improvement in formal thought disorder after initial stabilization in a first-episode sample.
Background: Neurocognitive deficits have been suggested to predict treatment response in patients with first-episode schizophrenia. However, studies targeting putative neurocognitive mechanisms to explore improvement in positive psychotic symptoms and especially formal thought disorder are lacking.
Method: Formal thought disorder symptoms in 81 first-episode patients with schizophrenia or schizoaffective disorder either showed significant improvement (responders > 60% change) or not (nonresponders < 60%) 6 months after initial stabilization of symptoms. These two groups were compared on neuropsychologic (n = 16), clinical (n = 15), and volumetric measures of the frontal and temporal lobes (n = 5) in univariate analyses. The variables that significantly differed between these two groups were used in a forward binary logistic regression analysis.
Results: As compared with nonresponders, responders were younger at time of testing, had higher verbal intelligence and reading achievement scores, higher scores on the arithmetic subtest of the Wechsler Adult Intelligence Scale-Revised, and lower number of perseverative responses on the Wisconsin Card Sort Test. Responders also had larger frontal lobe volumes than nonresponders. Only two measures (perseverative responses on the Wisconsin Card Sort Test and age at testing) entered the regression equation. Measures of semantic competency and volumetric measures of the temporal lobes were not associated with formal thought disorder improvement.
Conclusions: Neurocognitive deficits are associated with treatment response in formal thought disorder in first-episode patients with schizophrenia. The improvement in formal thought disorder is more strongly linked to executive than semantic function in this sample, pointing to the salience of frontal systems in treatment response in positive psychotic symptoms.