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Objective: To investigate the association of folic acid (FA) supplementation with birth weight, the risk of small for gestational age (SGA) and low birth weight (LBW) in singleton and twin pregnancy.Design: A population-based cross-sectional survey.Setting: Twenty counties and ten districts in Shaanxi Province of northwestern China, 2013.Participants: 28 174 pregnant women with their infants, covering 27 818 single live births and 356 twin live births.Results: The prevalence of FA supplementation in singletons and twins was 63·9 and 66·3 %. The mean birth weight was 3267 (sd 459·1) g, 2525 (sd 534·0) g and 2494 (sd 539·5) g; the prevalence of SGA was 14·3, 51·4 and 53·4 %; the prevalence of LBW was 3·4, 42·4 and 46·6 % among singleton, twin A and twin B, respectively. Compared with non-users, women with FA supplementation were (β 17·3, 95 % CI 6·1, 28·4; β 166·3, 95 % CI 69·1, 263·5) associated with increased birth weight, lower risk of SGA (OR 0·85, 95 % CI 0·80, 0·92; OR 0·45, 95 % CI 0·30, 0·68) and LBW (OR 0·82, 95 % CI 0·71, 0·95; OR 0·50, 95 % CI 0·33, 0·75) in singletons and twins, and more prominent effects in twins. Moreover, there were significant interactions between FA supplementation and plurality on birth weight, SGA and LBW.Conclusions: The present study suggests the association of periconceptional 0·4 mg/d FA supplementation with increased birth weight and reduced risk of SGA and LBW in both singletons and twins, and this association may be more prominent in twins. [ABSTRACT FROM AUTHOR]

Background: Twin studies have lacked statistical power to apply advanced genetic modelling techniques to the search for cognitive endophenotypes for bipolar disorder.Aims: To quantify the shared genetic variability between bipolar disorder and cognitive measures.Method: Structural equation modelling was performed on cognitive data collected from 331 twins/siblings of varying genetic relatedness, disease status and concordance for bipolar disorder.Results: Using a parsimonious AE model, verbal episodic and spatial working memory showed statistically significant genetic correlations with bipolar disorder (rg = |0.23|-|0.27|), which lost statistical significance after covarying for affective symptoms. Using an ACE model, IQ and visual-spatial learning showed statistically significant genetic correlations with bipolar disorder (rg = |0.51|-|1.00|), which remained significant after covarying for affective symptoms.Conclusions: Verbal episodic and spatial working memory capture a modest fraction of the bipolar diathesis. IQ and visual-spatial learning may tap into genetic substrates of non-affective symptomatology in bipolar disorder. [ABSTRACT FROM AUTHOR]

Background: Depression rises markedly in adolescence, a time when increased and new genetic influences have been reported.Aims: To examine'new'and'stable' genetic and environmental factors on depressive symptoms in adolescence and young adulthood.Method: A questionnaire survey investigated a sample of twin and sibling pairs at three time points over an approximately 3-year period. Over 1800 twin and sibling pairs reported depressive symptoms at the three time points. Data were analysed using multivariate genetic models.Results: Depressive symptoms at all time points were moderately heritable with substantial non-shared environmental contributions. Wave 1 genetic factors accounted for continuity of symptoms at waves 2 and 3. 'New'genetic effects at wave 2 also influenced wave 3 symptoms. New non-shared environmental influences emerged at each time point.Conclusions: New genetic and environmental influences may explain age-related increases in depression across development. [ABSTRACT FROM AUTHOR]

Previous research has suggested that prenatal testosterone exposure masculinises disordered eating by comparing opposite- and same-gender twins. The objective of the current study is to replicate this finding using a sample of 439 identical and 213 fraternal females, 461 identical and 344 fraternal males, and 361 males and 371 females from opposite-gender twin pairs. Disordered eating was compared across twin types using the Eating Disorder Inventory-2. Inconsistent with previous findings, a main effect of co-twin gender was not found. Our results raise questions about the validity of prior evidence of the impact of prenatal testosterone exposure on patterns of disordered eating. [ABSTRACT FROM AUTHOR]

The article focuses on the issue regarding the development of mental health research in Sri Lanka. Psychiatry around the world provides a useful example of the mutual benefits of international collaboration in psychiatric re- search. It has been describe that collaborative research approach necessary to build research capacity in the country. The setting up of the Sri Lankan twin registry was used as an example. It highlights the need for parallel development of bioethical guidelines designed to protect the ml interest from commercial exploitation. It also permits the sufficient flexibility to support the development of new ideas.