To explore the characteristics of prefrontal cortex activation by near-infrared spectroscopy (NIRS) in depressed patients who also had suicide ideation or committed suicide.

Total 23 patients who suffered major depression disorder (MDD) complicated with suicide behavior (suicide behavior group), 28 MDD patients bearing suicide ideation without behavior (suicide ideation group), and 26 healthy controls, matched with the gender, age, and education, were tested by category verbal fluency task (VFT). During the task, 52-channel FOIRE-3000 of Shimadzu was used to collect the relative concentration of oxygenate hemoglobin (Oxy-Hb) from all three groups.

There was no significant difference between suicide behavior group and suicide idea group in their VFT performance (F=11.196, P>0.05), which however were both lower than the healthy control group (P<0.05); the Oxy-Hb exchange of the bilateral orbitofrontal cortex and bilateral dorsolateral prefrontal cortex in suicide behavior group and the suicide idea group were significantly lower than the healthy control group (P<0.05).

The activity of the prefrontal cortex in MDD patients who had suicide ideation or committed suicide is significantly lower with the most prominent change found in bilateral orbitofrontal cortex and bilateral dorsolateral prefrontal cortex.

Depressive disorder; Prefrontal cortex; Spectroscopy, near-infrared; Verbal fluency task; Suicide