Association between severe dorsolateral prefrontal dysfunction during random number generation and earlier onset in schizophrenia

ObjectivesSchizophrenia involves impairment in attention, working memory and executive processes associated with prefrontal cortical function, an essential contributor of social functioning. Age at onset is a major factor for predicting social outcome in schizophrenia. In clinical settings, we need an objective assessment tool for evaluating prefrontal function and social outcome.MethodsParticipants included 22 right-handed patients with schizophrenia and 40 gender- and age-matched healthy controls. We used a 52-channel near-infrared spectroscopy (NIRS) instrument to measure oxygenated haemoglobin ([oxy-Hb]) changes over the prefrontal cortex during a random number generation (RNG) task.ResultsIn healthy controls, we found significant [oxy-Hb] increase in the bilateral dorsolateral (DLPFC; BA9 and BA46) and ventrolateral prefrontal cortex (VLPFC; BA44, 45 and 47). The patients with schizophrenia showed significantly smaller activation than the healthy controls in the same approximate regions. In the patient group, a smaller [oxy-Hb] increase in the right DLPFC region (BA9) was significantly correlated with earlier age at onset.ConclusionsNIRS can detect prefrontal cortical dysfunction associated with an executive task, which was coupled with earlier age at onset in schizophrenia.SignificanceMultichannel NIRS, a non-invasive and user-friendly instrument, may be useful in evaluating cognitive function and social outcome in clinical settings in psychiatry.

► This study addresses the need for an objective assessment tool evaluating prefrontal function and social outcome non-invasively in the clinical setting. ► Such a tool would be valuable for studies of the pathophysiology of schizophrenia and in the evaluation of patients with schizophrenia. ► Multichannel near-infrared spectroscopy is a non-invasive and user-friendly instrument, and may be useful in evaluating cognitive function and social outcome in clinical settings in psychiatry.