Objective: Are there differences in working memory task related oxygenated hemoglobin (HbO) in dorsolateral prefrontal cortex in those with schizophrenia, who had committed instrumental violence as opposed to reactive aggression? Is there any relationship to the severity of such aggression?

Methods: 22 stable forensic psychiatric inpatients with schizophrenia spectrum disorders (20 schizophrenia) were rated on symptom scales. Their most severe aggressive act was rated according to Cornell’s classification of instrumental or reactive aggression. The severity of aggression was also noted. Subjects completed a computerized Corsi-block-tapping test during functional near infrared spectroscopy (fNIRS). Correlation analyses and GLM were used to identify factors that correlated with oxygenated hemoglobin signal in optodes 1 and 15 (dorsolateral prefrontal cortex DLPFC).

Results / Discussion: Spearman Rank correlations with task-minus-baseline HbO in optode 1(left DLPFC) were found for total antipsychotic daily dose and scores on block 5 of the Corsi task, as well as between daily dose and negative symptom scores. Correlations were found between baseline HbO in optode 1 and 15, as well as in task-minus-baseline.  There was no effect of type of aggression on optode 1 or 15 baseline or task-minus-baseline HbO when controlled for the above. Past severe aggression, controlled for SANS, daily dose and Corsi correct responses correlated with higher HbO at baseline in optode 15 (F=9.45 p=0.007, adj R2=0.33, p=0.032) as opposed to task related HbO. Baseline and task-minus baseline optode 1 HbO correlated only with antipsychotic dose and Corsi score.