# Comorbidity network of post-traumatic stress and depressive symptoms during the COVID-19 pandemic in Korea

## TL;DR

This study examines how post-traumatic stress and depressive symptoms are connected during the COVID-19 pandemic in Korea, finding that sleep problems consistently act as a bridge between these symptoms.

## Contribution

The study identifies sleep problems as a consistently central and bridging symptom in the comorbidity network of PTSS and depression during the pandemic.

## Key findings

- Sleep problems were consistently identified as the most influential bridge symptom across all pandemic phases.
- The network structure of symptoms changed over time, but sleep problems maintained their central role.
- Prompt screening for sleep problems could help prevent comorbidity between PTSS and depression in future pandemics.

## Abstract

The coronavirus disease 2019 (COVID-19) pandemic had direct effects on population health through infection and morbidity, as well as indirect effects on population mental health. We estimated the network structure of post-traumatic stress symptoms (PTSS) and depressive symptoms throughout the pandemic in Korea and aimed to identify the most central and bridging symptoms.

Participants aged 30–64 years completed mental health surveys across 3 phases of the COVID-19 pandemic: March 2020 (n=1,925), February–March 2021 (n=1,754), and December 2021–January 2022 (n=1,595). Using PTSS and depressive symptom data, we conducted network analyses, and the primary measures of symptom importance (centrality) were expected influence and bridge expected influence.

In the comorbidity network, although the most central symptoms fluctuated over the course of the pandemic, sleep problems were consistently identified as the most influential bridge symptoms throughout. The symptom network structure differed between the subacute and chronic phases of the pandemic.

We found evidence of changes in the network structure of PTSS and depressive symptoms, even as sleep problems retained a consistent role as a bridging symptom. Although overall network structures varied across phases of the pandemic, the bridging role of sleep-related symptoms remained consistently strong, suggesting that sleep problems may represent a general and enduring mechanism underlying PTSS–depression comorbidity. During future pandemics, prompt screening for sleep problems may help prevent the development of comorbidity between PTSS and depressive symptoms.