Research news in brief

Chocolate consumption linked with lower risk of atrial fibrillation

Regular chocolate consumption may be linked to a lower risk of developing atrial fibrillation (AF) and flutter, according to US research published in Heart. AF affects more than 33 million people worldwide, with one in four adults likely to develop it at some point during the life course. Regular chocolate consumption, particularly of dark chocolate, has previously been linked to improvements in various indicators of heart health. Since recent evidence suggests that the pathophysiology of AF involves an inflammatory process, the authors hypothesised that the anti-inflammatory benefits of cocoa may also be associated with a lower rate of AF. Researchers from Beth Israel Deaconess Medical Center in Boston drew on 55 500 (26 400 men and 29 100 women) participants, aged between 50 and 64 years, from the population-based Danish Diet, Cancer and Health study. Participants provided information on their usual weekly chocolate consumption, with one serving classified as 30 g, although they did not specify which type of chocolate they ate. Most chocolate eaten in Denmark is milk chocolate (minimum 30% cocoa solids). Information on heart disease risk factors, diet and lifestyle was obtained when the participants were recruited to the study. Their health was then tracked using national registry data on episodes of hospital treatment and deaths. Those at the higher end of chocolate consumption tended to consume more daily calories (with a higher proportion of these coming from chocolate), and to be more highly educated than those at the lower end of the scale. During the monitoring period, which averaged 13.5 years, 3346 new cases of AF were diagnosed. After accounting for other factors related to heart disease, compared with participants who consumed chocolate less than once a month, the newly diagnosed AF rate was 10% lower for participants who consumed one to three servings of chocolate a month, 17% lower for those consuming one weekly serving, 20% lower for two to six weekly servings and 14% lower for one or more daily servings. When the data were analysed by sex, the incidence of AF was lower among women than among men irrespective of intake, but the associations between higher chocolate intake and lower risk of AF remained even after accounting for potentially influential factors. The strongest association for women seemed to be one weekly serving of chocolate (21% lower risk), while for men, it was two to six weekly servings (23% lower risk). However, a linked editorial from doctors at the Duke Center for AF in North Carolina highlighted a number of limitations of the study, including that the chocolate eaters were generally healthier and more highly educated, which may have influenced the findings.

High fibre diet linked to lower risk of knee osteoarthritis

Combined findings from two long term studies indicate an association between a fibre-rich diet and a lower risk of painful knee osteoarthritis (OA). Dietary fibre is known to reduce body weight and inflammation, both of which are linked with knee OA. Thus, researchers from Tufts University in Massachusetts mined data from two US studies in a bid to find out if dietary fibre may have any bearing on the risks of x-ray evidence of knee OA, symptomatic knee OA (x-ray evidence and symptoms, such as pain and stiffness), and worsening knee pain. Data were taken from the Osteoarthritis Initiative (OAI) of 4796 participants and the Framingham Offspring Osteoarthritis Study (Framingham) of 1268 persons. For both studies, dietary fibre intake was measured at baseline using Food Frequency Questionnaire responses. Information on symptoms and x-ray evidence were collected every year for 4 years in the OAI and assessed after 9 years in the Framingham study. Data were also gathered on potentially influential factors, such as knee injury or surgery, medication and lifestyle, including tobacco and alcohol use and physical exercise. At the end of 4 years, among the 4051 participants in the OAI with complete data on dietary fibre intake, 869 knees were symptomatic, 152 displayed x-ray evidence of OA and pain had worsened in 1964. In the Framingham study, after an average of 9 years, among the 971 participants with complete dietary fibre data, 143 knees were symptomatic and 175 displayed x-ray evidence of OA. The study found that patients with the lowest fibre intake (bottom 25% of participants) had a 30% lower risk of painful knee OA than those with the highest fibre intake (top 25%) in the OAI, and a 61% lower risk in the Framingham study. But it was not associated with x-ray evidence of knee OA. In addition, among the OAI participants, eating more fibre in general and a high cereal fibre intake were associated with a significantly lower risk of worsening knee pain. This is an observational study, so no firm conclusions can be drawn about cause and effect. The findings were published in the Annals of the Rheumatic Diseases.

Pregnancy complications linked to early coronary disease in offspring

Complications of pregnancy, such as high blood pressure and infections, may be linked to a heightened risk of early coronary heart disease in the young adult offspring, finds Australian and Dutch research published in Heart Asia. More than 600 million people live in South East Asia, most of whom are under the age of 65 years. Both maternal pregnancy complications and premature cardiovascular disease are major health problems in South-East Asia. Rates of premature deaths attributable to non-communicable diseases in this region are high, with around one in three deaths due to non-communicable diseases occurring before the age of 60 years. To find out if complications of pregnancy may be associated with the risk of early coronary heart disease, the researchers compared 153 patients with acute coronary syndrome with the same number of healthy people matched for age and sex. The patients had been diagnosed with cardiovascular disease before the age of 55 years, and admitted to a single cardiac centre in eastern Indonesia. Detailed information was collected from both groups on background social and economic factors, current lifestyle, cardiovascular risk factors and parents’ history of heart disease, and this was combined with the results of a physical examination and relevant lab tests. Maternal medical history included complications of pregnancy — specifically, high blood pressure; premature birth; and any respiratory, gut, genitourinary, malarial or dengue fever, measles, chickenpox and unspecified infections that had lasted for at least 3 days or had required admission to hospital. Patients with premature heart disease were more likely to have relevant risk factors than their healthy counterparts. These included high blood pressure, diabetes, eating an unhealthy diet and smoking. In addition, significantly more mothers of patients with premature cardiovascular disease had experienced pregnancy complications (30 mothers; 19.6%) than mothers of controls (11 mothers; 7.2%, P = 0.003). When all the data were analysed, participants whose mothers had experienced a complication of pregnancy were almost three times as likely to develop early coronary artery heart disease as those whose mothers had had a problem-free pregnancy. The findings held true, irrespective of potentially influential risk factors, such as lifestyle and unfavourable lab test results. The researchers acknowledged that this was an observational study so no firm conclusions could be drawn about cause and effect. Moreover, the small size and single-centre nature of the study may limit the generalisablity of the findings.

Brain images reveal roots of kids’ increasing cognitive control

As children age into adolescence and on into young adulthood, they show dramatic improvements in executive functions – the ability to control impulses, stay organised and make decisions – which are key factors in determining outcomes, including educational success, drug use and psychiatric illness. Researchers from the University of Pennsylvania have now mapped the changes in the network organisation of the brain which underlie those improvements in executive function. The study, published in Current Biology, reveals that the maturing brain becomes increasingly segregated into distinct network modules for greater efficiency. The findings show that the degree to which executive function improves in a person with age depends on the degree to which that well defined modular network structure emerges. They researchers used data from a sample of 882 youths between the ages of 8 and 22 years who completed diffusion imaging as part of the Philadelphia Neurodevelopmental Cohort, a community-based study of brain development that includes rich neuroimaging and cognitive data. As expected, executive function improved markedly in study participants with age. An analysis of the brain images revealed an increasingly specialised and modular structure that was nonetheless fully integrated. The findings suggest that modular brain architecture is critical for the development of complex cognition and behaviour. They may also lead to the identification of biomarkers of abnormal brain development that could predict a person’s risk for psychosis and major mood disorders, the researchers say. They suggest that a globally integrated network architecture may be critical for supporting specialised processing and reducing interference between brain systems. At the same time, the increase in global integration may allow those specialised parts to work together in a coordinated fashion. The researchers also found a relationship between the emergence of that modular structure and a person’s performance on tests of executive function.

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