Ineffective initiation contributes to deficient verbal and non-verbal fluency in patients with schizophrenia

Patients with schizophrenia (SCH) show impaired verbal and non-verbal fluency. However, these individuals' fluctuations in words or designs generation efficiency over time, a phenomenon that may significantly affect fluency, have never been studied. Thus, the aim of this research was to investigate if individuals with SCH may present with alternations in the dynamics of the information production and its control as well as to test if the potential abnormalities in this regard might affect these patients' overall performance on both verbal and non-verbal fluency tasks.

Forty-four patients with SCH and 40 healthy controls (HC) completed both verbal (phonological, semantic) and non-verbal fluency tests. To analyse processing efficiency changes over time, the period in which subjects had to generate words or designs (60 s) has been divided into 15-s sections.

In comparison to HCs, individuals with SCH obtained significantly lower total scores for all fluency measures. Furthermore, group differences in the dynamics of the test performance also emerged, with SCH patients having a significantly worse production during the initial 15 s of each fluency task. Additionally, the initial production deficiency seen in patients with SCH has accounted for these individuals' total performance. Moreover, comparisons of errors distribution over time during the phonemic and figural fluency performance also revealed differences, suggesting there was a rapid depletion in maintaining of cognitive control in the SCH sample.

Inefficient fluency in SCH may arise from a more general initiation deficits that may partly account for these patients' cognitive problems.