Correlation between frontal lobe oxy-hemoglobin and severity of depression assessed using near-infrared spectroscopy

- Biomarkers of depression severity have not been established.
- Near-infrared spectroscopy (NIRS) can potentially assess the relationships between clinical symptoms and neurobiology.
- We recruited a case sample with various psychiatric disorders, including major depression, and used the Hamilton Rating Scale for Depression (HAMD) to assess severity.
- NIRS showed a negative correlation between oxy-Hb in the frontal lobe and HAMD scores.
- Our results highlight the importance of applying neurobiological understanding for practical use.

IntroductionThe 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.MethodsEnrolled 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.ResultsWe 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).DiscussionOur results support blood flow in the frontal lobe as a potential biomarker of depression severity across various psychiatric disorders.LimitationLimited sample size, no replication in the second set.