Press Release - 06 August 2020


Cumulative impact of protracted social conflicts and COVID-19 pandemic adds up to aggravate PTSD and Depressive symptoms in Hong Kong


Prolonged successions of multiple events hit mental health differently from one-off events and has been seldom studied. We present evidence that different events can add up cumulatively to induce 2 types of mental distress: (1) stress reactions, and (2) established disorders. The two types are both manifested in high symptom levels but could be discriminated by “symptom reactivity”.

The YMH Team at the HKU Department of Psychiatry ( conducted a large-scale survey (involving over 10,000 individuals) together with an anonymous self-help mental health tool (the “Flow Tool”, since February 2020. The aims were to 1) facilitate awareness on mental health and offer resources for self-help, 2) offer suggestions on when to seek professional help, and 3) help understand the causes of mental distress and ways to address them.


Salient Findings

11,493 participants completed the tool up to July 2020. 41% participants reported high levels of PTSD symptoms (TSQ≥6); 74% reported moderate to severe levels of depression (DASS-D≥14). Most of the time (90%), high levels of PTSD symptoms were accompanied by significant depressive symptoms.

Specific types of external events were associated with increased risks for PTSD and depressive symptoms, respectively (Figure 1). Of the variables tested, the odds ratio for PTSD risk in those with experiences of social unrest traumatic events was as high as 11-fold. Even viewing such events online increased odds of PTSD risk by nearly two-fold. COVID-19 and other personal stressful life events also increased the risks for PTSD.

Other risk factors for both PTSD and depressive symptoms included lower resilience, inadequate sleep, reliance on smartphones, conflicts with friends, early adversity, and past psychiatric history. Female gender predicted more PTSD symptoms but not depressive symptoms. Additional risk factors for depressive symptoms were conflicts with family. Traumatic events, PTSD and Depressive symptom levels are significantly higher in young people under the age of 25.

In the presence of continuous stressors, a high level of symptoms may reflect (1) established disorders (2) “temporary” reactions to stress perpetuated by stressor persistence. Symptom reactivity (transient relief from symptom) suggests milder, temporary reactions to external events. Lack of reactivity suggests more severe and established disorders.

Figure 1: Odds ratios for (a) PTSD symptoms and (b) depressive symptoms

Figure 2: Cumulative impacts of life events, COVID-19 pandemic events and social unrest events for (a) PTSD symptoms and (b) depressive symptoms

Figure 3: Symptom reactivity: disorders or reactions


  1. Use of online prediction tools can facilitate accessibility to screening for a large sector of the population. This would be particularly useful when population-level stressors are protracted. However, it does not replace in-person professional evaluations.
  2. Individuals can use tools such as the Flow Tool ( to evaluate their symptom levels. Those with higher symptom levels should review their symptom reactivity (available in the Flow Tool).
  3. Among participants presenting moderate to severe levels of symptoms, 45.5% (n=4,084) showed non-reactivity in either PTSD or depression. Persons showing low to non-reactivity are advised to consider seeking professional help.
  4. Individuals in the stress-reactive category should also aim to reduce risk factors and increase modifiable protective factors identified (e.g., increase resilience and social support, limit smartphone use, and better sleep habit) to prevent mental health risks.
  5. Prior exposure to trauma can intensify response to pandemic stress. Narrowly focusing on current stress events may not sufficiently address the cumulative mental health needs In a situation of continuous and ongoing population stress, more attention should be paid to support individuals with prior trauma exposure to facilitate recovery to prepare for better coping with emerging new stressors.

For more information, you can download the presentation slides.