The social environment plays a considerable role in determining major psychiatric disorders. Emerging evidence suggests that features of the social environment modify gene expression independently of the primary DNA sequence through epigenetic processes. Accordingly, dysfunction of epigenetic mechanisms offers a plausible mechanism by which an adverse social environment gets “into the mind” and results in poor mental health. The purpose of this review is to provide an overview of the studies suggesting that epigenetic changes introduced by the social environment then manifest as psychological consequences. Our goal is to build a platform to discuss the ways in which future epidemiologic studies may benefit from including epigenetic measures. We focus on schizophrenia, major depressive disorder, post-traumatic stress disorder, anorexia nervosa, and substance dependence as examples that highlight the ways in which social environmental exposures, mediated through epigenetic processes, affect mental health.

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Bladder cancer is common in Western countries, but not in Japan. Established risk factors are smoking and high-risk jobs such as printing and manufacturing. The risk of alcohol consumption in bladder cancer has been the recent focus; however, available literature on alcohol consumption and bladder cancer has been limited from Japanese population, thought to have a weak genetic tolerance to acetaldehyde. We aimed to determine whether alcohol consumption is an independent risk factor for bladder cancer among Japanese. The study was a matched case-control study from the nationwide Japanese clinical database administered by the Rosai Hospital group. We identified 739 cases of bladder cancer diagnosed between 2005 (when the database was established) and 2014 and 7,196 controls matched by sex, age, hospital, and admission period. We estimated the odds ratio of alcohol consumption for bladder cancer adjusted for the amount of smoking, high-risk occupations, and comorbidities (hypertension, hyperlipidemia, diabetes, hyperuricemia, and obesity) with conditional logistic regression. The risk of bladder cancer was significantly higher in ever drinkers than in never drinkers (odds ratio, 1.33; 95% confidence interval, 1.06 to 1.66). Furthermore, the risk threshold for alcohol consumption was more than 15 g of alcohol intake per day (one, 180-mL cup equivalent to 6 ounces of Japanese sake containing 23 grams of alcohol). Among Japanese, alcohol consumption may be an independent risk factor for bladder cancer, with a lower risk threshold.

ObjectiveThe aim of this study was to identify the relevant obstetric factors for cerebral palsy (CP) after 33 weeks’ gestation in Japan.Study designThis retrospective case cohort study (1:100 cases and controls) used a Japanese national CP registry. Obstetric characteristics and clinical course were compared between CP cases in the Japan Obstetric Compensation System for Cerebral Palsy database and controls in the perinatal database of the Japan Society of Obstetrics and Gynecology born as live singleton infants between 2009 and 2011 with a birth weight ≥ 2,000 g and gestation ≥ 33 weeks.ResultsOne hundred and seventy-five CP cases and 17,475 controls were assessed. Major relevant single factors for CP were placental abnormalities (31%), umbilical cord abnormalities (15%), maternal complications (10%), and neonatal complications (1%). A multivariate regression model demonstrated that obstetric variables associated with CP were acute delivery due to non-reassuring fetal status (relative risk [RR]: 37.182, 95% confidence interval [CI]: 20.028–69.032), uterine rupture (RR: 24.770, 95% CI: 6.006–102.160), placental abruption (RR: 20.891, 95% CI: 11.817–36.934), and preterm labor (RR: 3.153, 95% CI: 2.024–4.911), whereas protective factors were head presentation (RR: 0.199, 95% CI: 0.088–0.450) and elective cesarean section (RR: 0.236, 95% CI: 0.067–0.828).ConclusionCP after 33 weeks’ gestation in the recently reported cases in Japan was strongly associated with acute delivery due to non-reassuring fetal status, uterine rupture, and placental abruption.