Cardiovascular medicine

Winter getting you down? It might also be making you unhealthy

March 19, 2010 No Comments

Do the long nights and shoddy weather over the winter months make you feel low? If so, you could also be at raised risk of cardiovascular disease and being overweight, according to new research in PLoS ONE.

This study of 11,545 Norwegian adults found that people who were classified as having considerable variations in mood across the seasons had a higher BMI and waist to hip ratio, and higher levels of fat in their blood, than people who were less affected by the seasons.

In addition, women who had “high seasonality” tended to do less exercise and were more likely to smoke daily than their “low seasonality” counterparts. All these factors add up to an elevated risk of cardiovascular disease, according to the study authors.

The most well known variant of seasonal mood changes is seasonal affective disorder (SAD), which is characterised by severe episodes of depression that only occur during a particular time of year. SAD affects an estimated 7% of the UK population every winter between September and April, in particular during December, January, and February. Seasonality is distinguished by milder variations in mood rather than major lows, although high seasonality combined with a propensity for depression is thought to be a risk factor for SAD.

People with SAD or high seasonality tend to eat more, gain weight, and feel more sleepy during episodes. This could be advantageous from an evolutionary point of view, because it could facilitate energy storage and promote reproductive potential in the seasons optimal for conception, gestation, and lactation. In the modern world, however, we have access to resources all year round and don’t have to worry about energy storage, so seasonality may conversely be a stress factor.

In the new PLoS ONE study, all individuals in Hordaland county, Norway, born between 1953 and 1957 (i.e. aged 40–45 years) were invited to participate, 63% of whom said yes. These 8,598 men and 9,983 women filled in questionnaires about their seasonal fluctuations in mood and behaviour and about their health behaviours. Blood samples were taken and height, weight, waist circumference, hip circumference, and blood pressure were measured.

In both men and women, weight, BMI, waist-hip ratio, and blood levels of triglycerides increased as the level of seasonality increased. For example, the average BMI for men with low seasonality was 25.9, a touch overweight but otherwise fine, but for men with high seasonality to the point of having SAD the average BMI was 27.1, definitely overweight.

Women with high seasonality were about 20% less likely to do at least three hours of exercise a week than their less affected counterparts, and tended to drink and smoke more. Furthermore, the association between seasonality and BMI in women was affected by when the researchers took their measurements: BMI increased over autumn and winter in women with high seasonality.

Given the high BMI, weight, and blood fat levels in people with high seasonality, the authors state that “Overall it seems to be fair to conclude that subjects with high seasonality have an elevated risk for cardiovascular disease.” They do point out that a cross-sectional study such as theirs can’t pinpoint causation though: we don’t know whether high seasonality causes poor health or whether poor health is responsible for high seasonality.

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Øyane N et al. (2010) Increased Health Risk in Subjects with High Self-Reported Seasonality. PLoS ONE 5 (3). DOI: 10.1371/journal.pone.0009498

Cardiovascular medicine, Diet and nutrition

Obese children are at high risk of death before middle age

February 19, 2010 1 Comment

A study published in the New England Journal of Medicine has found that children who were obese were almost twice as likely to die before 55 years of age than those who were not obese. Moreover, children whose weight was in the top 25% out of nearly 5,000 kids were 2.3 times more likely to die from diseases before middle age than those whose weight fell in the bottom 25%.

The authors of this big, long study looked at body mass index (BMI; a measure of weight that takes into account a person’s height) and risk factors for cardiovascular disease in 4,857 children aged 5-19 years who lived on an American Indian reserve in Arizona.

BMI and markers of cardiovascular disease were measured in all children when the study started in 1966 or after. The participants were then followed up until their death, their 55th birthday, or the end of 2003, whichever came first.

A total of 559 (11.5%) participants died before the age of 55, 166 (3.4%) of whom died from a disease or from self inflicted injury such as alcohol or drug abuse – so-called “endogenous causes.”

Children whose BMI fell within the top 25% of all those in the study were 2.3 times more likely to die from endogenous causes before the age of 55 than those whose BMI was in the lowest 25%. In fact, each one unit increase in BMI increased the risk of early death from endogenous causes by 40%. This relationship persisted but at a slightly lower level once factors like cholesterol level and blood pressure were taken into account.

The authors then looked specifically at the 1394 (28.7%) children who were obese – those whose BMI fell in the top 5% on growth charts from governmental public health body the Centers for Disease Control and Prevention. Compared with non-obese children, these kids were 31% more likely to die before they reached 55.

Children with high blood glucose levels – a sign that diabetes might be on the horizon – were at 73% higher risk of dying early, whereas those with hypertension were at 57% higher risk. This link prompted the authors to say that the link between obesity and premature death “may be partially mediated by the development of glucose intolerance and hypertension in childhood.”

Childhood cholesterol level and blood pressure, however, had no effect on the risk of premature death from endogenous causes.

Speaking to the New York Times, senior author Helen Looker said, “This suggests that obesity in children, even prepubescent children, may have very serious long-term health effects through midlife — that there is something serious being set in motion by obesity at early ages. We all expect to get beyond 55 these days.”

American Indians were studied because childhood obesity has been common for decades in this ethnic group. The prevalence of obesity in young Arizona Pima Indians in the 1960s, when this study was initiated, was similar to that seen in Hispanic and African American children today, so hopefully the results from this long study should be generalisable to kids today.

In a linked editorial, Edward W Gregg of the Centres for Disease Control and Prevention pointed out: “Since the trends with respect to obesity and diabetes among the Pima Indians have been a reliable harbinger for trends in the rest of the U.S. population during recent decades, the present study should intensify the debate about whether interventions that are initiated during childhood and young adulthood can affect our broader diabetes epidemic.”

Furthermore, in a previous study the same authors found that BMI correlated closely with total body fat – adiposity – and that adiposity in turn correlated with cardiovascular risk factors. By extension, the link between BMI and early death in this study suggests that actual body fat is linked with early death.

This is important because BMI is an imperfect measure of weight – for example, some very muscular people might be heavy for their height and thus have a high BMI – thus despite the study results weight might not genuinely be associated with early death. On the other hand, high adiposity – “fatness” – is a more indicative of an unhealthy weight.

“Childhood obesity is becoming increasingly prevalent around the globe. Our observations, combined with those of other investigators, suggest that failure to reverse this trend may have wide-reaching consequences for the quality of life and longevity,” conclude the study authors.

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Franks P et al. (2010) Childhood Obesity, Other Cardiovascular Risk Factors, and Premature Death. New England Journal of Medicine 362 (6): 485-493. DOI: 10.1056/NEJMoa0904130

Arts, Cardiovascular medicine

Clinical research from the heart

February 18, 2010 No Comments

Hot on the heels of Valentine’s day, the British Heart Foundation has announced the winners of their images competition “Reflections of Research,” in which UK scientists funded by the foundation were asked to submit the most striking still and video images of their research.

Winners of the video category are Dr Michael Markl of University of Freiburg, Germany, and Dr Philip Kilner of Imperial College London, and their video of blood flowing through the heart. Concentrate hard and you can see, in red/yellow, blood flowing through the left side of the heart, down the aorta, and into the body as the heart rotates. Blood flowing through the right side of the heart towards the lungs is shown in blue. According to the BBC, in the future doctors may be able to use this type of imaging to help simulate the blood flow in a patient’s heart.

Winners of the picture category were Mathieu-Benoit Voisin and Doris Proebstl from London with their remarkable heart shaped cell stain.

The researchers are studying how white blood cells move from the blood into into damaged tissue to cause inflammation; for example, after a heart attack. They were using using fluorescent pigments to stain two key players in this inflammatory process – pericyte cells from the blood vessel wall (stained red and blue) and collagen (green) – when looking through the microscope they noticed that the cells had arranged themselves into a heart shape.

“Through better understanding of how white blood cells interact with the components of the vessel walls, we hope to identify new avenues to treat conditions that underlie heart and circulatory inflammatory diseases,” said Dr Voisin. “Our research is funded by the British Heart Foundation so we were really delighted to see this heart shaped arrangement of cells appear by chance through the microscope!”

I think my favourite image from the competition is this runner up picture of the muscle fibres in the left ventricle of the heart.

The image, from Dr Patrick Hales at University of Oxford, was generated using diffusion tensor imaging of the heart. This magnetic resonance imaging (MRI) technique tracks the movement of water molecules through the heart muscle, which reveals how the muscle cells are aligned.

“This technology allows us to model the structure of muscles in the heart in a non-invasive way, and how diseases can cause it to change,” said Dr Hales. “In the future, we hope that our research might be able to determine how the structure of the heart is damaged during a heart attack, and how the muscle fibres respond.

“We also hope that our computer models of individual hearts will one day be used as a tool for diagnosis, and could even provide patient-specific assessment of treatment options. Imagine your doctor trying out treatments on a ‘virtual’ version of you, before choosing the right prescription.”

See all the shortlisted images on Flickr and the shortlisted videos on the British Heart Foundation website.

Cardiovascular medicine, Diet and nutrition, Public health

Reducing dietary salt by half a teaspoon could save 92,000 lives a year

February 5, 2010 1 Comment

A Californian population based study has found that if everyone in the US reduced their daily salt intake by 3 grams – half a teaspoon – the annual number of deaths could be slashed by up to 92,000. In addition, the number of new people who get cardiovascular disease each year could drop by up to 120,000 – that’s equivalent to the population of Cambridge!

In fact, cutting dietary salt intake by as little as 1 gram a day could reduce the number of deaths from any cause by 15,000 to 32,000 and the number of new cases of cardiovascular disease by 20,000 to 40,000.

US regulations recommend that people consume less than 5.8 g of salt a day, yet the average American man gets through almost double that – 10.4 g of salt daily. This is bad news – high salt intake is associated with an increased risk of stroke and cardiovascular disease.

In this study, published in the New England Journal of Medicine, the authors used computer modelling to simulate heart disease and stroke in US adults aged 35-84 years.

They found that a population wide reduction in dietary salt of 3 g per day could potentially reduce the annual number of cases of cardiovascular disease by 60,000 to 120,000, stroke by 32,000 to 66,000, and heart attack by 54,000 to 99,000. The annual number of deaths from any cause could be cut by by 44,000 to 92,000.

Even a modest reduction of 1 g of salt per day could cut the yearly rates of cardiovascular disease, stroke, and heart attack by at least 20,000, 18,000, and 11,000, respectively. “It was a surprise to see the magnitude of the impact on the population, given the small reductions in salt that we were modeling,” Kirsten Bibbins-Domingo, lead author of the study, told Science Daily.

The effects seemed greater in black people – a population with high rates of hypertension and cardiovascular disease – and women would benefit in particular from a reduction in stroke incidence. The number of events related to cardiovascular disease – such as heart attack – would drop in older adults, whereas young people would benefit from lower overall mortality rates.

The public health benefits of a drop in salt intake of 3 g a day would be equivalent to half of all smokers quitting or a 5% reduction in body fat among obese adults, and would save $10 billion to $24 billion a year in healthcare costs.

“Reducing dietary salt is one of those rare interventions that has a huge health benefit and actually saves large amounts of money,” said senior author Lee Goldman. “At a time when so much public debate has focused on the costs of health care for the sick, here is a simple remedy, already proven to be feasible in other countries.”

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Bibbins-Domingo K et al. (2010) Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease. New England Journal of Medicine DOI: 10.1056/NEJMoa0907355

Cancer, Cardiovascular medicine

Watching too much TV increases risk of death within the next six years

February 3, 2010 No Comments

A study of nearly 9,000 Australian adults has reported that people who watched 4 hours of TV a day or more were 46% more likely to die within the next six and a half years than those who watched less than 2 hours a day. Each one hour increase in daily television viewing increased the risk of death from any cause by 11% and death by cardiovascular disease by 18%.

Previous studies have suggested that sedentary behaviour is associated with a mortality risk. Furthermore, surveys in the US and the UK indicate that, aside from sleeping, lounging around watching television takes up the most of our time at home – about 3 hours a day in the UK and up to 8 hours a day in the US, apparently.

This study, published in the journal Circulation, examined 8,800 adults aged 25 years or older who were in the Australian Diabetes, Obesity and Lifestyle Study (AusDiab). All participants were interviewed at the start of the study to find out their lifestyle habits, medical history, and the amount of time they had spent watching television or videos in the previous 7 days.

About six and a half years later, on average, mortality status and cause of death for each participant was established from the Australian National Death Index.

Each one hour increase in television viewing time was associated with an 11% increase in the risk of death from any cause and an 18% increase in the likelihood of death related to cardiovascular disease. However, these relationships were attenuated once other factors like medical history and smoking habits were taken into account, but the association between TV time and death from any cause did remain important. The link between television viewing time and cancer mortality was negligible though.

Strikingly, the risk of mortality was much higher in people who watched at least 4 hours of TV a day than in those who watched less than 2 hours – the risk of death from any cause was 46% higher and the risk of death from cardiovascular disease was a whopping 80% more.

Individuals who watched 4 hours of TV a day or more were more likely to be a current or ex-smoker, have a poor diet, be overweight, or have raised blood pressure than those who watched less than 2 hours daily – that is, they seemed generally less healthy and, in theory, would be more likely to just drop dead. However, none of these factors affected the associations between television viewing and mortality.

The public health implications of this study are pretty serious – get TV addicts to cut their viewing in half and they could considerably reduce their risk of death over the next 6 years or so. As the authors say, “our findings suggest that reducing time spent watching television (and possibly other prolonged sedentary behaviors) may also be of benefit in preventing CVD and premature death.” They recommend that as well as promoting exercise, public health bodies should also “focus on reducing sitting time, particularly prolonged television viewing.”

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Dunstan D et al. (2010) Television Viewing Time and Mortality: The Australian Diabetes, Obesity and Lifestyle Study (AusDiab). Circulation 121 (3): 384-391. DOI: 10.1161/CIRCULATIONAHA.109.894824

Cardiovascular medicine

Does IQ affect cardiovascular disease risk?

July 24, 2009 3 Comments

Err, well, maybe. IQ does seem to account for some of the well-documented relationship between socioeconomic status and cardiovascular risk, according to new research in European Heart Journal. Simply put, being more intelligent could be one reason why people from a high socioeconomic background are less likely to die from cardiovascular disease than those who are more disadvantaged.

The authors of this study wanted to unravel how low socioeconomic status leads to cardiovascular disease and poor health. Factors like access to resources (e.g. education and income) and environmental exposures (e.g. housing conditions) have a role, but taking account of these factors in calculations – effectively eliminating their influence – doesn’t level the playing field, meaning that there must be some other elements at play.

Previous studies have shown that IQ is inversely correlated with total mortality and cardiovascular mortality – that is, people with a high IQ are at least risk of death from any cause and death from heart disease.

Batty et al. looked at data from 4,289 male former US soldiers to establish the extent to which IQ ‘explains’ socioeconomic disparities in health. All participants took a general aptitude test when they joined the army between 1965 and 1971. Results from this test, as well as data on their income at 20 years of age, were combined with IQ, health and financial data gleaned from a telephone survey when the participants were on average 38 years old.

As expected, men who had a high IQ – both at 20 years old and at middle age – tended to have more favourable social circumstances, such as higher family income, than those with a lower IQ.

In a second analysis, socioeconomic status was inversely associated with total mortality, cardiovascular mortality and death from any cause. For example, men with a low current income or little education were more than six times more likely and three times more likely, respectively, to die from cardiovascular disease.

When the calculations were adjusted to take into account IQ scores at 20 years old, the huge differences in cardiovascular mortality between those who were well off and those who were less fortunate shrunk by a third; the disparity was reduced by more than half when IQ score at middle age was added instead.

Adjusting for other risk factors for cardiovascular disease – such as blood pressure and cholesterol level – had less of an effect on the mortality differences between the most fortunate and the least fortunate, suggesting that IQ has more of an effect on risk of cardiovascular disease according to socioeconomic status than do traditional risk factors.

The implication of this study is that efforts directed at reducing socioeconomic disadvantage to improve health should also include educational opportunities as well as improving housing and so on.
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Batty G et al. (2009) Does IQ explain socio-economic differentials in total and cardiovascular disease mortality? Comparison with the explanatory power of traditional cardiovascular disease risk factors in the Vietnam Experience Study. European Heart Journal 30 (15): 1903-1909. DOI: 10.1093/eurheartj/ehp254

Cardiovascular medicine

Cycling or walking to work reduces risk of obesity and cardiovascular disease… but only in men

July 20, 2009 2 Comments

OK, so it seems pretty obvious that cycling or walking to work is better for you than taking the car. New research published in Archives of Internal Medicine has clarified the beneficial effects in terms of fitness and cardiovascular health of walking or cycling to work – but they’re largely only seen in men.

This study assessed 2,364 adults from four US states, and found that less than a fifth (16.7%) used active means to get to work. Men who walked or cycled to work were fitter (able to run for longer on a treadmill) and were less likely to be obese (had a lower body mass index) than those who commuted by car, bus, train or subway. Female active commuters were fitter than their more sedentary counterparts, but no less likely to be obese.

In addition, men who walked or cycled to work were at lower risk of cardiovascular disease, as they had lower levels of a range of cardiovascular disease biomarkers (i.e. blood levels of triglycerides and fasting insulin, and diastolic blood pressure). This inverse correlation was not seen in women though.

So why the difference between men and women? Well, women were less likely to be active commuters (15.6% of women versus 18.0% of men), and those who were active commuters were more likely to walk than cycle (82.8% in women versus 64.1% in men). Although the median distance to work for active commuters was 5 miles for both men and women, men would cycle or walk up to 13.5 miles whereas the maximum commute in women was 10 miles. It seems that women need to commute a bit further and at a higher intensity of exercise in order to see weight and cardiovascular benefits of active commuting.

The authors of this study conclude that nonleisure forms of exercise such as active commuting can help people increase their levels of physical activity and have beneficial effects on health.
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Penny Gordon-Larsen, Janne Boone-Heinonen, Steve Sidney, Barbara Sternfeld, David R Jacobs Jr, Cora E Lewis (2009) Active Commuting and Cardiovascular Disease Risk: The CARDIA Study. Arch Intern Med 169(13): 1216-1223. PMID: 19597071

Cardiovascular medicine, Public health

Here it is, your heart

January 12, 2009 No Comments

The British Heart Foundation has launched a new advertising campaign that features an amazing real-time simulation of a beating heart.

The campaign confronts viewers with the perhaps gory but nevertheless fascinating reality of the most vital of vital organs, and challenges them to think about heart and circulatory disease – Britain’s biggest killer.

British Heart Foundation Director of Policy and Communications, Betty McBride, said, “We wanted to confront people with the reality of what a working heart looks like. This is a rare chance for people to see in incredible detail how it works. We expect people to react in lots of different ways – whether it’s amazed, squeamish or disturbed. It’s vital that we get people to take time to think about their heart health.”

The Virtual Heart Simulator was developed in a collaboration between specialists at The Heart Hospital in London and design agency Glassworks. The British Heart Foundation boasts that this fantastic video represents “the biggest technical advancement since Leonardo da Vinci sketched the heart 500 years ago.”

The campaign advertises the guidance and advice that the British Heart Foundation provides, not least through its Heart Helpline, where cardiac nurses and information officers are on hand 9am-10pm, seven days a week, to provide free confidential information on heart health issues.

The campaign website also features a helpful A-Z of the heart, which explains in plain english cardiology terms such as ‘supraventricular tachycardia’ and ‘cardiomyopathy’.

You can call the Heart Helpline on 0300 333 1 333, or alternatively peruse the British Heart Foundation website www.bhf.org.uk for stacks of information on heart health

Cardiovascular medicine

Drinkers don’t take their medications often enough

December 22, 2008 No Comments

alcohol A recent study by Bryson et al. has found that moderate to severe alcohol misuse increases the likelihood that patients won’t take their medication properly.

Many patients do not take their medications as often as they should – i.e. on at least 80% of the days they are supposed to. In fact, a recent study found that over the space of a year, 40% of patients taking cardiovascular or diabetes medications didn’t take their medications often enough. Such ‘medication nonadherence’ is associated with worsening of disease, increased health care costs, and even death.

Bryson et al. looked at more than 20,000 patients who were receiving treatment for high blood pressure, high cholesterol levels, or diabetes. All participants undertook a three-point questionnaire to evaluate their alcohol use on the basis of frequency and typical quantity of drinking during the past year, and the frequency of heavy episodic drinking (at least 6 drinks per occasion). Medication adherence over the space of a year was measured by how often patients went back to their pharmacy for a refill.

Among patients taking medication for high blood pressure or high cholesterol levels, nonadherence increased as the severity of alcohol misuse increased. Compared with patients who did not drink, the proportion of patients who did not stick to their cardiovascular medications was significantly higher among those who moderately or severely misused alcohol. Interestingly, there was no difference in adherence to diabetes medications between diabetic patients who did not drink and those who did.

This research might seem like it’s straight from the department of the obvious: “Of course people with alcohol problems don’t take their medications properly!” There are a couple of key findings that are important to bear in mind though. For one, the authors were able to assess alcohol consumption with a brief questionnaire , unlike previous studies on this subject that used lengthy, time consuming interviews. Thus the approach used in this study could be used easily in clinical practice.

In addition, a fair few studies have examined the problem of medication nonadherence, but most have found that the factors responsible for nonadherence are ones that would be very difficult to modify, such as older age (over 80 years old) or low socioeconomic status. The study by Bryson et al. is important because it identifies a modifiable factor responsible for medication nonadherence. Counsel a patient to cut their drinking and, in theory, they should be more likely to take their medication properly, which would keep their condition in check and enable them to get on with their life unhindered.

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Bryson CL et al. (2008) Alcohol screening scores and medication nonadherence. Ann Intern Med 149 (11): 795-803. PMID: 19047026

Cardiovascular medicine, Public health

British Heart Foundation petition against cigarette machines

November 23, 2008 No Comments

The British Heart Foundation has launched a petition to ban the sale of cigarettes from vending machines in the UK. The charity hopes that banishing cigarette vending machines will reduce the number of under 18s who take up smoking.

In the UK you need to be at least 18 years old to buy cigarettes from a shop and, technically, this old to get cigarettes from a vending machine. Vending machines aren’t manned, however, making it easier for under 18s to circumvent this rule and get their hands on cigarettes. 66% of adult smokers started when they were under age, so stopping people from taking up smoking as teenagers is crucial to prevent a livelong addition to cigarettes.

According to the BHF, 6% of children aged 11-15 are regular smokers and as many as one in six of these teenagers buy their cigarettes from cigarette vending machines. A 2007 study reporting on test purchases by young people found that teenagers were able to buy cigarettes from vending machines on more than four in ten occasions, with a number of councils reporting a 100% successful purchase rate. Using vending machines was the most successful way for young people to get hold of cigarettes – almost twice as successful as other ways tested such as purchasing cigarettes from a newsagent, off licence or petrol station kiosk.

Smoking is a leading risk factor for heart disease – of the 114,000 smokers who die as a result of smoking each year in the UK, one in four die from cardiovascular disease. Measures to help people quit smoking, or stop them from smoking in the first place, are thus a key part of the BHF’s strategy.

You can help put cigarette vending machines out of order for good by signing the BHF petition here.

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