Publications

Prevention of cardiovascular disease and diabetes is a priority in low- and middle-income countries, especially in South Asia where these are leading causes of morbidity and mortality. The metabolic syndrome is a tool to identify cardiometabolic risk, but the validity…

Previous studies have shown associations between major depression and C-reactive protein (CRP) levels. Few studies have considered the extent to which shared genetic and environmental factors contribute to this association, nor have they considered the relationship outside of European populations.…

Anxiety not only concerns mental wellbeing but also negatively impacts other areas of health. Yet, there is limited research on (a) the genetic and environmental aetiology of such relationships; (b) sex differences in aetiology and (c) non-European samples. In this…

Biobanks are a valuable resource for creating advancements in science through cutting-edge omics research. Twin research methods allow us to understand the degree to which genetics and environmental factors contribute to health outcomes.

We investigated the heritability of educational attainment and how it differed between birth cohorts and cultural–geographic regions. A classical twin design was applied to pooled data from 28 cohorts representing 16 countries and including 193,518 twins with information on educational…

Kan, Carol MRCPsych, PhD; Jayaweera, Kaushalya MD; Adikari, Anushka MD; Siribaddana, Sisira FRCP; Zavos, Helena M.S. PhD; Harber-Aschan, Lisa PhD; Sumathipala, Athula PhD; Hotopf, Matthew PhD, FRCPsych; Ismail, Khalida MRCPsych, PhD; Rijsdijk, Frühling PhD Psychosomatic Medicine  Volume 82 – Issue 2 doi:…

Life events have been associated with a variety of mental health conditions including depression. There is a scarcity of research in South Asia exploring the aetiology of independent and dependent life events and their relationship with depression symptoms. This study…

Worldwide, 10%–20% of children and adolescents experience mental health conditions. However, most such disorders remain undiagnosed until adolescence or adulthood. Little is known about the factors that influence mental health in children and adolescents, especially in low and middle-income countries…

This study investigated the genetic and environmental contributions to emotional overeating (EOE) and depressive symptoms, and their covariation, in a Sri-Lankan population, using genetic model-fitting analysis. In total, 3957 twins and singletons in the Colombo Twin and Singleton Study-Phase 2…

Describe sleep duration in adult Sri Lankans and determine the bias and agreement of self-report and actigraphic assessments.

The disease burden related to mental disorders and metabolic syndrome is growing in low-and middle-income countries (LMIC). The Colombo Twin and Singleton Study (COTASS) is a population-based sample of twins and singletons in Colombo, Sri Lanka. Here we present prevalence…

Monozygotic (MZ) and dizygotic (DZ) twins participate in research that partitions variance in health, disease, and behavior into genetic and environmental components. However, there are other innovative roles for twins in medical research

Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal…

Genes and the environment contribute to variation in adult body mass index [BMI (in kg/m2)], but factors modifying these variance components are poorly understood.

There is a genetic contribution to the risk of suicide, but sparse prior research on the genetics of suicidal ideation.

The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index…

Human height variation is determined by genetic and environmental factors, but it remains unclear whether their influences differ across birth-year cohorts. We conducted an individual-based pooled analysis of 40 twin cohorts including 143,390 complete twin pairs born 1886–1994. Although genetic…

Both genetic and environmental factors are known to affect body mass index (BMI), but detailed understanding of how their effects differ during childhood and adolescence is lacking.

We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number…

Twin pairs are either monozygotic (MZ) or dizygotic (DZ). Diagnosis of zygosity has traditionally been based on sex, genetics and/or chorionicity (Derom et al. Twin Res, 2001;4:134–6). A monochorionic placenta, determined using first-trimester ultrasound scans and confirmed by placental examination…

A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances…

For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how…

Alcohol use is increasing in non-Western countries. However, the effects of this increase on the prevalence of alcohol use disorders (AUD) remains unknown, particularly in South Asia. This study aimed to estimate the prevalence of alcohol use and AUD in…

The International Network of Twin Registries (INTR) aims to foster scientific collaboration and promote twin research on a global scale by working to expand the resources of twin registries around the world and make them available to researchers who adhere…

Most studies of post-traumatic stress disorder (PTSD) in low- and middle-income countries (LMICs) have focused on ‘high-risk’ populations defined by exposure to trauma.

The Sri Lankan Twin Registry (SLTR), established in 1997, is a unique resource for twin and genetic research in a low- and middle-income country (LMIC). It comprises of a volunteer cohort of 14,120 twins (7,060 pairs) and 119 sets of…

Little is known about the prevalence and etiology of tobacco use in Asian populations. This study aims to test whether the finding of substantial heritability for tobacco-related phenotypes in Western populations is generalizable to developing countries.

Somatic symptoms often co-occur with psychological symptoms but this overlap is poorly understood. Some aspects of this overlap differ in the South Asian context, but it is not clear whether this is a reporting effect or an underlying difference in…

Fatigue is a common symptom in Western high-income countries but is often medically unexplained and little is known about its presentation in other populations. To explore the epidemiology and aetiology of fatigue in Sri Lanka, and of its overlap with…

It is important to understand the nature of depression in non-Western and lower-income countries, but little such research exists. This study aimed to examine the characteristic features of depression in Sri Lanka, and to identify environmental risk factors.

There is very little genetically informative research identifying true environmental risks for psychiatric conditions. These may be best explored in regions with diverse environmental exposures. The current study aimed to explore similarities and differences in such risks contributing to depression…

Susceptibility to depression results from genetic and non-familially shared environmental influences in high-income, Western countries. Environments may play a different role for populations in different contexts.

The Sri Lankan Twin Registry began as a volunteer register in 1997. Previously, we have shown door-to-door surveys as the best option to build a population-based twin register of older, adult twins. Our aim was to build a population-based twin…

The National Twin Registry of Sri Lanka was established in 1997 as a volunteer register. To extend it to a population-based register, we examined the effectiveness of tracing older twins by inspecting birth records and recruiting them by postal invitation…

Sri Lanka is an island with genetic diversity between the five main population groups. Our twin registry is the first in the developing world. Initially, we established a volunteer cohort of 4600 twin pairs through a competition advertised in the…

Identifying twins for a population-based register can be achieved through birth records or community surveys. We studied the feasibility and effectiveness of different methods of identifying and recruiting twins to establish a population based register.

Nearly all twin registers are based in developed countries and there is no twin register in the developing world. Our objectives were to initiate the process of establishing a nationwide twin register in Sri Lanka by starting a volunteer register…

We report the process of adaptation into Sinhala of a questionnaire given to mothers of twins to determine zygosity. Adaptation and validation was carried out in three stages. Firstly, we used a nominal group to translate the English version and…