An international team led by Dr. Ali Jawaid from the institute found that from a group of 2,700 people who had shown signs of depression, anxiety disorders or post-traumatic stress disorder before the coronavirus pandemic, in Poland 54% had experienced a deterioration of their mental health.

They also found that there were significant differences between the studied countries. For example, in Canada, the percentage was over 81%. The Nencki Institute team also identified factors that increase the probability of health deterioration in people who previously showed symptoms of mental disorders.

The feeling of lack of control turned out to have the most negative impact on the psyche. It increased the probability of health deterioration by 90%. Other factors increasing this probability were female gender (70%), lack of interaction with others (56%) and dissatisfaction with the state's response to the pandemic (31%). Over 13,000 people from 12 countries participated in the study.