Background

The current outbreak of the novel coronavirus disease 2019 (COVID-19), has rapidly spread across China and many other countries.The outbreak is still ongoing, which posed a huge threat to the global public health and economic[1]. The local government in many cities of China announced the suspension of public transportation from January 23, 2020. In order to prevent a large cross-provincial population flow, most college students are forced to stay at home and continue their studies in the form of online classes. Subthreshold depression (SD) is generally considered to present when individuals show depressive symptoms but diagnostic criteria for a major depressive disorder are not met, which also known as subclinical depression, subsyndromal depression or minor depression[2]. As a transitional stage of depression, the SD may deteriorate into depression or recover with intervention[3,4]. Those at highest risk of development from SD to a full-blown depression would benefit most from prompt treatment[5]. Recently, the advances of functional Magnetic Resonance Imaging (fMRI) allow the exploration of the neural underpinnings of various neurological and psychiatric disorders,identifying the biological markers of SD is essential to prevent depression.This study is the first survey of psychological effects Combined with fMRI in the college students with subthreshold depression after a month of the epidemic outbreak in China.

Methods

In total,49 SD individuals and 56 health controls(HC) were recruited from Jinan University, Guangzhou, China during 2018-2019. The students were aged from 18 to 28 years. Each subject was assessed using a standardized clinical evaluation protocol that included the Center for Epidemiologic Studies Depression Scale (CES-D), 24-item Hamilton Depression Rating Scale(HAMD).Inclusion criteria for StD participants included: (1) CES-Dscore ≥ 16; (3) 24-item HAMD score between 8-20. Exclusion criteria included: (1) psychiatric disorders;2) any history of a concurrent, major physical illness and neurological disorders; 3)substance abuse or dependence. HC participants were recruited from the same sources as StD participants based on the age and gender status of selected StD participants. All HC participants have a CES-D score of less then 16, 24-item HAMD score less then 8，and satisfied the same exclusion criteria as StD participants. All subjects underwent MRI and MATRICS Consensus Cognitive Battery (MCCB)before COVID-19 outbreak. MRI images were obtained on a 3.0T MR scanner (GE Discovery MR750 System).The 7-minute scan of rs-fMRI data were acquired using gradientecho echo-planar imaging (EPI) sequence.The image preprocessing was taken on Data Processing & Analysis of Brain Imaging (DPABI_V2.3)[6]which is based on Statistical Parametric Mapping(SPM12). Then regional homogeneity(ReHo) analysis [7]was calculated to measure the ReHo value of the similarity of time series of a given voxel to its nearest 26 neighboring voxels in a voxel-wise way. The MCCB assesses 8 cognitive domains: Speed of Processing, Attention/Vigilance, Working Memory, Verbal Learning, Visual Learning, Reasoning and Problem Solving, Social Cognition and Overall Comp. A month after a COVID-19 outbreak in China (February 28 to March 21,2020),we conducted an online questionnaire survey of all the above SD students. Impact of Event Scale-Revised (IES-R) is a self-report measure designed to assess current subjective distress caused by traumatic life events. We set SD students with IES-R score less than 20 as experimental group 1(SD1), SD students with a score greater than or equal to 20 as experimental group 2(SD2), and the HC did not carry out IES-R questionnaire survey. ANOVA was used to compare resting-state ReHo values and MCCB cognitive domains among the three groups. Statistical significance was set at p < 0.05 (GRF corrected). Bonferroni multiple comparison correction tests (at p <0 .05) were used for post hoc analyses of paired comparisons when the results of ANOVA showed significant differences. A Pearson correlation was made to compare the ReHo values of abnormal brain regions, MCCB cognitive domains among the three subject groups with the IES-R scores.

Results and disscusion

The total number of participants in the experiment was 23 in SD1 group ,26 in SD2 group and 56 in HC group.As illustrated in Fig.1, the brain map showed the medial prefrontal cortex with different reho values in three groups(Peak MNI coordinate: 15,44,22). After post hoc analyses, SD1 Showed increased reho value compared with HC(t=3.857 p=0.000), SD2 showed decreased reho value compared with t=3.857 p=0.000). In SD1 group ,Our study did not find any significant correlations between the IES-R scores and the ReHo values in regions that showed significant differences in the three group (p=0.545). But in the SD2 group, we found a positive correlation between the reho values of the different brain regions and the IES-R return scores(Fig. 2,p=0.032). The results of relationship between MCCB and IES-R scores are similar to those above. In SD1 group ,the study did not find any significant correlations between the IES-R scores and the MCCB Overall Comp scores that showed significant differences in the three group (p = 0.626). In the SD2 group, we found a negative correlation between scores of cognitive domain dimension synthesis and the IES-R return scores(Fig.3,p=0.041).

Conclusion

Although college students with subthreshold depression did not meet the diagnostic criteria for depression, there had been changes in the brain area (medial prefrontal lobe). After the COVID-19 epidemic situation, changes of brain area and cognitive function of college students with significant stress symptoms were more obvious.

Acknowledgements

No acknowledgement found.

References

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