The role of the bilateral inferior frontal gyrus in non-suicidal self-injury (NSSI) among depressed adolescents: A functional near-infrared spectroscopy (fNIRS) study during verbal fluency tasks

Background: The diagnosis and treatment of adolescents engaging in non-suicidal self-injury (NSSI) have been a clinical focus. We examined the hemodynamic changes in verbal fluency tasks (VFT) of adolescents with depression and NSSI, and its association with NSSI indexes.

Methods: Seventy-three adolescents with depression and NSSI and sixty-nine healthy controls (HCs) were employed. The VFT was performed by functional near-infrared spectroscopy (fNIRS). Independent-sample t-test, correlation analysis, and liner regression were measured.

Results: In the VFT, reduced hemodynamic changes were found in the NSSI group, including thirteen channels. Totally seven ROIs were defined according to which brain region these channels had the largest coverage and other channels that also belonged to it. They are the right inferior frontal gyrus (RIFG, t = -2.53, FDR corrected p = 0.02), right middle frontal gyrus (RMFG, t = -3.47, FDR corrected p = 0.002), right superior frontal gyrus (RSFG, t = -2.98, FDR corrected p = 0.005), left middle frontal gyrus (LMFG, t = -3.26, FDR corrected p = 0.002), left inferior frontal gyrus (LIFG, t = -2.80, FDR corrected p = 0.001), left precentral gyrus (LPrCG, t = -2.22, FDR corrected p = 0.03), and left supramarginal gyrus (LSMG, t = -2.20, FDR corrected p = 0.03). Negative correlations were found between the frequency of NSSI and the bilateral IFG (RIFG, r = -0.28, p = 0.01; LIFG, r = -0.26, p = 0.03). BDI and BAI have positive correlations with the frequency of NSSI (BDI: r = 0.42, FDR corrected p < 0.001; BAI: r = 0.41, FDR corrected p < 0.001), but results of liner regression showed that both of them do not affect the association between the frequency of NSSI and hemodynamic changes in bilateral IFG (RIFG, p = 0.01; LIFG, p = 0.04).

Conclusion: Adolescents with depression and NSSI have worse performance in the VFT, and lower activation in the bilateral IFG may represent a higher frequency of NSSI. These results help physicians enhance the understanding of adolescents with depression and NSSI.