Spatial pattern of brain activation during a Verbal Fluency Test in first ⁃ episode depressive disorder patients: a functional near⁃infrared spectroscopy study

Abstract

Objective To investigate the spatial pattern of the activation of the prefrontal and bilateral temporal cortex in first⁃episode depressive disorder patients during Verbal Fluency Test (VFT). Methods Forty first⁃episode patients who met the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM⁃5) depressive disorder and 14 normal controls were both measured of spatial pattern in the prefrontal and bilateral temporal cortex by functional near⁃infrared spectroscopy (fNIRS) during VFT, at the same time, the number of words produced during VFT was recorded. The severity of depressive symptoms was assessed by Zung's Self⁃Rating Depression Scale (SDS). The spatial pattern of brain activation during VFT was compared between 2 groups, and the correlation between the oxyhemoglobin (HbO2) integral value of prefrontal or bilateral temporal lobes and SDS score were explored by Pearson correlation analysis in depressive disorder group. Results SDS score of the depressive disorder patients was higher than that of control group (68.38 ± 12.91 vs. 35.98 ± 6.83; t=11.832, P=0.000). Compared with the control group, the scores of prefrontal and bilateral temporal lobes in depression group were significantly lower during VFT [(35.25 ± 41.74) mmol•mm vs. (149.91 ± 54.88) mmol•mm, t=⁃8.140, P=0.000; (84.05 ± 59.23) mmol•mm vs. (211.01 ± 81.27) mmol•mm, t=⁃6.250, P=0.000]. There was no significant difference in the number of words between 2 groups (11.27 ± 4.35 vs. 11.92 ± 5.55; t=⁃0.450, P=0.665). There was a negative correlation between the HbO 2 integral value of bilateral temporal lobes and SDS score in patients with depressive disorder (r=⁃0.330, P=0.039), and there was no significant correlation between the HbO2 integral value of prefrontal lobe and SDS score (r=⁃0.210, P=0.184). Conclusions During the VFT, the decrease of prefrontal and bilateal temporal lobes activation and the bilateral temporal lobes HbO2 integral value is negatively correlated with the degree of depression.

Keywords

• depression disorder
• cognition disorders
• spectroscopy
• near ⁃ infrared
• neuropsychological tests