Language dominance and verbal memory in patients with schizophrenia – a study using functional transcranial Doppler sonography (fTCD)

Aim: This study investigated frequency of atypical language dominance and its association to verbal memory in patients with schizophrenia and in healthy controls. Methods: In 18 right-handed patients (age: 39.6±12.5y) and 35 controls (age: 56.4±8.9y) language dominance was determined with functional transcranial Doppler sonography (fTCD): Cerebral blood flow velocity (CBFV) was measured continuously in both middle cerebral arteries (MCA) while conducting a word generation paradigm. Relative CBFV increase during word generation compared to resting and a laterality index (LI) representing the side difference in rCBFV were computed. Verbal memory (VLMT) and vocabulary (WST) was measured using established neuropsychological tests. Psychiatric symptoms were rated with the Brief Psychiatric Rating Scale (BPRS). Results: Frequency of atypical language dominance was similar in patients and controls (7% vs. 9%; p>0.1). RCBFV increase was lower in patients (left MCA: 10.5% vs. 14.0%; right MCA: 6.7% vs. 11.2%, p<0.05) and patients showed reduced verbal learning (p<0.01). In patients with a relatively strong left-sided language dominance (Median-Split) word recognition was by trend worse compared to patients with weaker left-sided dominance (p<0.1). Conclusion: A higher rate of atypical language dominance was not observed in schizophrenic patients. In patients, weaker language dominance seemed to be advantageous with respect to word recognition as a parameter of verbal memory.