The Effects Of Long-Term Transcranial Direct Current Stimulation On Patients With Subthreshold Depression

The harm of depression has aroused widespread attention in today’s society.A considerable number of studies have suggested a dual effect of physiological mechanisms and psychological models in depression patients.There are now relatively mature means to intervene in depression,among which tDCS has been widely praised as a cheap,rapid,safe,and harmless technology.With the development of epidemiological investigation in recent years,subthreshold depression has received increasing attention.It is commonly believed that the physiological and psychological characteristics of subthreshold depression are close to depression as patients with subthreshold depression in surveys show similar emotional performance and life characteristics to those with depression.However,previous studies did not deal with subthreshold depression in much detail.Whether subthreshold depression and depression demonstrate the same neural mechanism and psychological model and whether tDCS can effectively regulate the emotional status and cognitive ability of patients with subthreshold depression remain unknown.To address the above-mentioned issues,participants were divided into three groups:group of subjects with subthreshold depression who receive active stimulation(n=27),group of subjects with subthreshold depression who receive sham stimulation(n=22),and group of normal subjects who receive active stimulation(n=17).The left dorsolateral prefrontal cortex of the subjects was stimulated by tDCS for 2 consecutive weeks in this research.Meanwhile,participants conducted four behavioral experiments including the dot probe task,negative priming task,and modified Sternberg task,during which their behavioral data and EEG were recorded.The results suggested that the cognitive function of participants with subthreshold depression was closer to that of normal people.tDCS showed no significant effect on regulating the emotional status of patients with subthreshold depression yet it regulated their memory bias and reduced their alpha power,which indicated that tDCS can still be considered as a neural regulation means to treat subthreshold depression.This research is the first comprehensive investigation of the behavior and neural mechanism of subthreshold depression and the intervention effect of tDCS on subthreshold depression.Previous hypotheses about subthreshold depression were inaccurate and subthreshold depression should not be generalized as depression.On the contrary,its unique physiological basis and psychological characteristics should be re-examined so as to discover more targeted intervention methods.