Birth cohort studies are conducted by prospectively following the participants with a specific characteristic background from their birth or prenatal birth, and can explore the causal relationship of various factors with outcomes. In the UK, birth cohort studies with long-term follow-ups have been launched every ten years, which have provided many significant results and related useful policy recommendation. However, these have not necessarily intended to be launched as the national project with long-term observations, rather existing birth cohorts are accept to continue because of the excellent results and survey condition. In 1990s, birth cohort studies have been revalued as national resources, and widely used by domestic and international researchers. As the contribution to psychiatry and mental health, most of the cohort studies have been conducted to identify risk factors for onset of psychiatric diseases such as schizophrenia. Nowadays, broader studies were conducted and highly evaluated for the relationships between physical and psychological illnesses, and biological studies. Recent cohort studies also showed that cognitive abilities in childhood or adolescence was similar between those who later developed schizophrenia and those who experienced psychotic symptoms, suggesting that a spectrum in psychiatric diseases would be useful for elucidating the pathophysiology. In Japan, birth cohort studies which findings could be reflected on policy implications have been required as national resources. However, as there have been no birth cohort studies that have conducted for long-term follow-ups, there are little techniques and knowledge for launching and continuing a birth cohort study with low attrition, and providing evidences to society. It is necessary to establish these techniques and knowledge by learning from the UK cases within the cultural and social contexts in Japan. High quality routine studies including examination have been implemented in Japan in various fields such as perinatal and infant care, schools, work places, medical care, and the central and local governments. Supplementation of those data will be needed for high quality birth cohort studies. Until now, there has been no relevant law to conduct any data linkage between the data from various fields in research settings and it is necessary to be prepared.
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