{Reference Type}: Journal Article {Title}: Prevalence of mass social media-induced illness presenting with Tourette-like behavior in Germany between 2019 and 2021. {Author}: Hartung K;Klages C;Fremer C;Pisarenko A;Haas M;Jakubovski E;Szejko N;Brandt V;Müller-Vahl KR; {Journal}: J Psychiatr Res {Volume}: 177 {Issue}: 0 {Year}: 2024 Sep 11 {Factor}: 5.25 {DOI}: 10.1016/j.jpsychires.2024.07.011 {Abstract}: Starting in 2019, in Germany the first well documented outbreak of mass sociogenic illness induced by social media (mass social media-induced illness; MSMI) occurred presenting with functional Tourette-like behaviors (FTB). This study aimed to provide first data on the prevalence rate of MSMI-FTB in Germany between 2019 and 2021 in the general population. We conducted a large-scale representative population survey in cooperation with the USUMA market and social research institute. Between August and December 2021, n = 2.509 people (mean age: 49.5 years, range: 16-95 years, n = 1.276 females) were randomly selected, visited in their households, interviewed, and asked to answer for themselves, but also for close family members (n = 6.744). Thus, in total, we received answers for n = 9.253 people. Probable MSMI-FTB was found in n = 33 individuals (mean age at onset: 30.5 years, n = 8 females). Based on strict criteria, the diagnosis of MSMI-FTB was considered highly likely in 16/33 individuals (mean age at onset: 25.6 years, n = 2 females) corresponding to prevalence rates of 0.17% (CIlower = 0.10, CIupper = 0.28) and 0.36% (CIlower = 0.25, CIupper = 0.50), respectively. This is the first large-scale, population representative study investigating the prevalence of MSMI-FTB in the general population in Germany between 2019 and 2021. Based on the prevalence rates found, MSMI-FTB is highly relevant for health economy. Accordingly, we suggest educating healthcare professionals and the general public to avoid misdiagnosis and inefficient treatment.