Background: The measures concerning COVID-19 may increase Mental Health problems and decrease Friendship Quality. It is unclear how the measures around COVID-19 affect adolescents who are already...Show moreBackground: The measures concerning COVID-19 may increase Mental Health problems and decrease Friendship Quality. It is unclear how the measures around COVID-19 affect adolescents who are already at risk of Mental Health problems and who benefit from good Friendship Quality; adolescents with a history of childhood adversity (CA). Research is required to see how Mental Health and Friendship Quality possibly changes during the COVID-19-pandemic. Insight into this relationship can contribute to the improvement of care for adolescents with CA who struggle with Mental Health problems and Quality of Friendship. Methods: We recruited adolescents (N = 76, M_age= 22,41, SD = 2,68)who have experienced CA from the Resilience after Individual Stress Exposure(RAISE) which filled in a questionnaire before the lockdown(October 2019), in the first lockdown(April 2020) and during the relaxation of the COVID-19-measures(July 2020). The Mood and Feelings Questionnaire(MFQ) measured Mental Health and the Cambridge Friendship Questionnaire(CFQ) measured Friendship Quality. Results: The findings confirmed that Friendship Quality increased between October 2019 and April 2020(1, 70) = 8,032 p = .006). Also between October 2019 and July 2020 the Friendship Quality increased (F(1, 70) = 4,757, p = .033). Mental Health problems increased during the lockdown April 2020 and during the relaxation from the measures in July 2020 compared to October 2019 (oct-apr:F(1, 70)=6,595, p=.012; oct-jul: F(1, 70)=8,289, p= .005). Friendship and Mental Health interconnect with each other; adolescents with improved Friendship Quality between October 2019 and April 2020 and between October 2019 and July 2020 also have increased Mental Health during this periods (oct-apr: β=.301; t(71) =2.608; p=.011; oct-jul: β=.418; t(72)=3.731; p<.001). Conclusions: The increased Quality of Friendship could be caused by the use of social media to keep in touch with friends. CA is a risk factor to develop mental health problems and so is COVID-19. Therefore, it is not unlikely that mental health decreases during lockdown and relaxations. The mental health problems are not solved when there are more relaxations, this could be caused by the long waiting lists for receiving mental health care and suggests that the mental health problems are long-lasting. When friendships improve, mental health problems decrease. This indicates that friendship increases the resilience of adolescents.Show less