Global DNA hypomethylation and its correlation to the betaine level in peripheral blood of patients with schizophrenia.

Accumulating evidence suggests that aberrant epigenetic regulation is involved in the pathophysiology of major psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BD). We previously showed that the plasma level of betaine (N,N,N-trimethylglycine), a methyl-group donor, was significantly decreased in patients with first episode schizophrenia (FESZ). In this study, we identified decrease of global DNA methylation level in FESZ (N = 24 patients vs N = 42 controls), and found that global DNA methylation level was inversely correlated with scores on the global assessment of functioning (GAF) scale, and positively correlated with plasma betaine level. Notably, correlations between levels of betaine and its metabolites (N,N-dimethylglycine and sarcosine, N-methylglycine) were lower or lost in FESZ plasma, but remained high in controls. We further examined global DNA methylation levels in patients with chronic SZ (N = 388) and BD (N = 414) as well as controls (N = 430), and confirmed significant hypomethylation and decreased betaine level in SZ. We also found that patients with BD type I, but not those with BD type II, showed significant global hypomethylation. These results suggest that global hypomethylation associated with decreased betaine level in blood cells is common to SZ and BD, and may reflect common pathophysiology such as psychotic symptoms.

Heart rate during hyperphagia differs between two bear species.

Hyperphagia is a critical part of the yearly cycle of bears when they gain fat reserves before entering hibernation. We used heart rate as a proxy to compare the metabolic rate between the Asian black bear ( Ursus thibetanus) in Japan and the Eurasian brown bear ( Ursus arctos) in Sweden from summer into hibernation. In the hyperphagic period, black bears feed on fat- and carbohydrate-rich hard masts whereas brown bears feed on sugar-rich berries. Availability of hard masts has quantitative and spatial annual fluctuations, which might require increased activity and result in intraspecific stress. Using generalized additive mixed models we analysed the differences in heart rate between the two species. Black bears had decreased heart rates during summer but had doubled heart rate values throughout the hyperphagic period compared to brown bears. This letter illustrates the different physiological consequences of seasonal differences in food availability in two species of the same genus dealing with the same phenological challenge.

Purpose in life and tobacco use among community-dwelling mothers of early adolescents.

OBJECTIVES: The rising prevalence of tobacco use and tobacco-attributable deaths among women is of worldwide concern. In particular, smoking prevention for mothers in early midlife is a significant international public health goal. A higher sense of purpose in life (PIL) is thought to reduce detrimental health behaviours. However, little is known about the association between a sense of PIL and tobacco use. This study investigates this association among community-dwelling mothers of early adolescents. DESIGN: This population-based cross-sectional study uses a self-reported questionnaire from the Tokyo Early Adolescence Survey, a large community-based survey conducted in Japan between 2012 and 2015. SETTING: Participants were randomly recruited from the resident registries of three municipalities in Tokyo, Japan. PARTICIPANTS: A total of 4478 children and their primary parents participated. Responses from 4063 mothers with no missing data were analysed (mean age=42.0 years (SD=4.2)). MEASURES: Participants' tobacco use, including the number of cigarettes smoked per day, was documented using a questionnaire. PIL was assessed using a Purpose in Life scale derived from Ryff's Psychological Well-Being Scale. RESULTS: Greater PIL was associated with a decreased likelihood of tobacco use, even when adjusted for confounders (OR=0.80, 95% CI 0.70 to 0.91). Multinomial logistic regression analyses revealed that PIL was inversely associated with tobacco consumption among mothers. These associations remained after controlling for psychological distress, socioeconomic factors and frequency of alcohol consumption among moderate to heavy smokers (OR=0.70, 95% CI 0.57 to 0.86), while attenuated among light smokers. CONCLUSIONS: Increasing PIL may be a valuable intervention for reducing tobacco use among women in early midlife. This study can contribute to our understanding of the psychology of smoking behaviour and shed light on the targeted intervention to reduce tobacco use among early midlife mothers.