Published in The Lancet Child & Adolescent Health, the study aimed to provide robust insights into adolescent mental health trajectories in two different cultural contexts by comparing large samples of 11 to 16 years olds in London and Tokyo over time. The two studies are the Tokyo Teen Cohort (TTC) and the Resilience Ethnicity and Adolescent Mental Health (REACH) cohorts from South London. Both groups collected data in the period 2014 to 2020 and at three different time points as the teenagers grew older.
Researchers used the Short Mood and Feelings Questionnaire (SMFQ) to measure depressive symptoms.
By the age of 16 the difference in depressive symptoms between boys and girls in London was around twice as large as in Tokyo. The average level of depressive symptoms in teenage boys in Tokyo declined between ages of 11 and 16, whereas for boys in London it increased slightly over time, following a similar trajectory to that of teenage girls in Tokyo.
The study was funded by the Invitation Program for Foreign Researchers at the Tokyo Metropolitan Institute of Medical Science, the Economic and Social Research Council (ESRC), the ESRC Centre for Society and Mental Health, the Japanese Society for the Promotion of Science, and the European Research Council.
Currently the Global Gender Gap Index (GGGI) - an index designed to measure gender equality - ranks UK 15th out of 149 countries while Japan is ranked 125th. However, insights from young co-researchers from both cities suggests there are social influences at play which are not captured in these indexes. For example, teenage girls may assume adult roles and responsibilities at a younger age in London and there are lower levels of violence and crime in Tokyo. There are also differences in socioeconomic and political trends between the two places that could contribute to differences, for example, the prolonged period of austerity in the UK.
An important part of this study was to investigate the extent to which scores derived from the measure SMFQ can be meaningfully and appropriately compared across genders, ages, and contexts. While these tests are not perfect, they found no evidence of incomparable measurement, which suggests that any differences in SMFQ scores between groups are due to real differences in depressive symptoms rather than differences in reporting.
The team have been awarded 5 years of funding from Wellcome to investigate mechanisms underlying anxiety and dpression in teenage girls and boys. The project will start in April 2025 and will take place in the UK and in Japan. An important part of this new project is to centre youth voice at every step which should help improve understanding of the causes and solutions.
Trajectories of depressive symptoms among young people in London, UK, and Tokyo, Japan: a longitudinal cross-cohort study. Knowles G. et al (2025) The Lancet Child & Adolescent Healthhttps://doi.org/10.1016/S2352-4642(25)00059-8
Authors: Gemma Knowles, Daniel Stanyon, Syudo Yamasaki, Mitsuhiro Miyashita, Charlotte Gayer-Anderson, Kaori Endo, Satoshi Usami, Junko Niimura, Naomi Nakajima, Kaori Baba, Thai-sha Richards, Jonas Kitisu, Adna Hashi, Karima Shyan Clement-Gbede, Niiokani Tettey, Samantha Davis, Katie Lowis, Verity Buckley, Dario Moreno-Agostino, Esther Putzgruber, Holly Crudgington, Charlotte Woodhead, Kristi Priestley, Katherine M Keyes, Jacqui Dyer, Shuntaro Ando, Kiyoto Kasai, Mariko Hiraiwa-Hasegawa, Craig Morgan, Atsushi Nishida, Tokyo Teen Cohort Young Persons Advisory Group
For more information please contact the ESRC Centre for Society and Mental Health, King’s College London via csmh@kcl.ac.uk.