Higher BMI levels may increase the risk of cardiovascular problems in youngsters

A recent study has shown that greater than normal Body Mass Index (BMI) may trigger unhealthier cardiovascular condition in young adults aged as young as 17.

The study was prsented at the Conference of the European Society of Human Genetics. Dr Kaitlin Wade, a Research Associate at the Medical Research Council Integrative Epidemiology Unit (MRC-IEU) at the University of Bristol, Bristol, UK, and assistants used statistics from The Avon Longitudinal Study of Parents and Children (ALSPAC) to scrutinize the possible connection between increased BMI and cardiovascular health.

She said, "ALSPAC is a world-leading birth cohort study, started in the early 1990s with the inclusion of more than 14,000 pregnant mothers and their partners and children, and provides an excellent opportunity to study environmental and genetic contributions to a person's health and development. It was therefore ideal for this purpose."

The scientists discovered that cardiovascular threat increased because of higher levels of BMI and was expected to occur earlier in life.

However, the current plan of existing observational studies (those just looking for associations in the population) meant that they are unable to make a distinction between association and causation.

The team could use genomic information from ALSPAC to find out the likely contributing relationship between higher BMI and higher blood pressure as well as left ventricular mass index (LVMI) in those aged 17 and 21. When the left ventricle wall thickens in the heart (hypertrophy) it means that it must work harder to pump blood and is a common indicator for heart disease.

"Our results showed that the causal impact of higher BMI on cardiac output was solely driven by the volume of blood pumped by the left ventricle (stroke volume). This, at least in part, can explain the causal effect of higher BMI on cardiac hypertrophy and higher blood pressure that we observed in all our analyses," noted Dr Wade.

The findings of the scientific study support efforts to undertake the obesity scourge from an early age to prevent the development of cardiovascular changes which precede cardiovascular ill-health and heart disease.Dr Wade shared, "It is the first time that the nature of this relationship has been shown in group of young adults where it has been possible to draw improved conclusions about its causation."

The researchers are now attempting to unravel the association between higher BMI and disease mechanisms which will include metabolomics (the study of the chemical processes involved in the functioning of cells and the abundance and diversity of microbes living in the gut - the gut microbiome). "We have also begun an analysis of the causal role of higher BMI on detailed measures of cardiac structure and function within the ALSPAC data. We hope to further explore these associations within an older population - the UK 1946 birth cohort," said Dr Wade.

He concluded by saying, "Whilst randomised controlled trials are important for disentangling cause and effect in disease, they are expensive, time-consuming and labour-intensive. Modern genomics allows us to detect causality more quickly and cheaply, and the availability of large quantities of genetic data means that we can overcome the limitations of observational epidemiological studies. We believe that there are clear messages for cardiovascular health in our findings and we hope that they may lead to increased efforts to tackle obesity from early life."

Professor Joris Veltman, Director of the Institute of Genetic Medicine at Newcastle University¸ Newcastle, United Kingdom, noted, "Distinguishing between correlation and causation is tremendously difficult in medical sciences, especially for complex interactions like those between obesity and cardiovascular disease. In this study, statistical genetics approaches were applied to longitudinal cohorts from the UK to improve this. The scientists could demonstrate that obesity also causes poorer cardiovascular health in young adults. In contrast, higher BMI did not seem affect heart rate in this group."