RESUMO
INTRODUCTION: The search for objective biomarkers of psychiatric disorders has a long history. Despite this, no universally accepted instruments or methods to detect biomarkers have been developed. One potential exception is near-infrared spectroscopy, although interpreting the measures of blood flow recorded with this technique remains controversial. In this study, we aimed to investigate the relationship between recorded blood flow and depression severity assessed using the Hamilton depression scale in patients with various psychiatric disorders. METHODS: Enrolled patients (n=43) had DSM-IV diagnoses of major depressive disorder (n=25), bipolar disorder I (n=5), schizophrenia (n=3), dysthymic disorder (n=3), psychotic disorder (n=3), panic disorder (n=2), and Obsessive Compulsive Disorder (n=2). The verbal fluency task was administered during blood flow recording from the frontal and temporal lobes. RESULTS: We found that severity of depression was negatively correlated with the integral value of blood flow in the frontal lobe, irrespective of psychiatric diagnosis (F=5.94, p=0.02). DISCUSSION: Our results support blood flow in the frontal lobe as a potential biomarker of depression severity across various psychiatric disorders. LIMITATION: Limited sample size, no replication in the second set.