Archive for April 2016

Take a nap: It’s good for your heart

April 29, 2016
Photo by Ludosphère

Photo by Ludosphère

Poor sleep is likely to make you feel grumpy and unfocused, but more importantly it puts you at risk for serious medical conditions such as obesity, type 2 diabetes and heart disease — and it shortens your lifespan.

A new study shows that sleep loss also increases your risk of cardiovascular disease by changing how your body metabolizes cholesterol.

Recently reported in Scientific Reports, University of Helsinki’s sleep team studied the cholesterol metabolism of sleep-deprived people, measuring their gene expression and the levels of blood lipoprotein, a molecule that transports cholesterol through the blood. They assessed these factors for a small group of volunteers who only slept four hours per night for five days. The team also looked at longer-term effects on cholesterol metabolism using data from two large population studies with 2739 participants.

The study found that people getting insufficient sleep have fewer high-density lipoproteins (HDL) — the “good” proteins that act as cholesterol scavengers to decrease accumulation of atherosclerosis within the walls of arteries — than people who get enough sleep.

“It is particularly interesting that these factors contributing to the onset of atherosclerosis, that is to say, inflammatory reactions and changes to cholesterol metabolism, were found in the experimental study and in the epidemiological data,” said Vilmo Aho, a graduate student at the University of Helsinki, in a recent news release.

The bad news is they showed that even a week of sleep deprivation had a significant impact. Aho explained in the release:

The experimental study proved that just one week of insufficient sleep begins to change the body’s immune response and metabolism. Our next goal is to determine how minor the sleep deficiency can be while still causing such changes.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Familial Hypercholesterolemia: A genetic disease in need of early testing

April 26, 2016

New research shows that familial hypercholesterolemia — a genetic condition that leads to high LDL cholesterol — is commonly diagnosed late and patients often don’t get adequate treatment. FH can cause aggressive and premature heart disease, including heart attacks, strokes, narrowing heart valves and sudden cardiac death.

Joshua Knowles, MD, PhD, assistant professor of cardiovascular medicine and chief medical advisor for the FH Foundation, is senior author of a new study that characterizes adult FH patients in the United States using data from the new CASCADE FH Registry™. As reported in Circulation: Cardiovascular Genetics, the study found many flaws in the current treatment of patients with FH. I spoke with Knowles about this silent and deadly disease:

What is Familial Hypercholesterolemia?

Familial Hypercholesterolemia is the medical term given to very high cholesterol that runs in families. We say, ‘We never find an individual with FH. We only find families with FH.’

It’s caused by genetic mutations that control the body’s ability to recycle LDL cholesterol. Your liver makes cholesterol and sends it through the bloodstream. Your body takes what it needs and then sends excess LDL cholesterol back to the liver for recycling.

In FH patients, the liver cannot recycle LDL cholesterol because there are defects in some receptors that pull the cholesterol from the blood. Therefore, the LDL levels remains very high in the blood, which is toxic to the blood vessels over time. If you have FH, your LDL cholesterol levels are two to three times higher than normal and that puts you at a much, much higher risk of early onset coronary disease such as heart attacks.

How is FH diagnosed?

There are over a million people in the US with this disorder, but less than ten percent have been diagnosed. In the US, genetic testing hasn’t become standard of care yet, largely due to the cost. So usually FH is diagnosed with a clinical point system based primarily on your personal and family medical history.

If you’re not diagnosed and treated, your risk of a heart attack is extremely high. However, if you are diagnosed, you can be treated and live a long and healthy life. So it’s a poster child for preventative and personalized medicine.

How is FH treated?

 Lifestyle changes — like improving your diet or exercising — are almost never enough for FH patients. FH patients need to be treated with medications that lower their LDL cholesterol. For most people with high cholesterol, one drug is sufficient. However, many FH patients require more than one drug.

The most common and important medications for FH are statins, which work by tricking the body into activating the LDL recycling program. Normally for every gene, you have one copy from Mom and one copy from Dad. In the most common form of FH, you’ve inherited the mutation from one parent. So you have one receptor in the liver that works well and one that doesn’t work at all. The statin drug tricks the body into increasing the levels of the good receptors to compensate for the bad ones — basically putting the good receptors in overdrive to activate the LDL recycling program.

What do you recommend for patients with a family history of early heart disease?

Really the biggest and best thing is to get your cholesterol tested when you’re young, when nothing but the genetic condition causes high cholesterol. If you wait until your 60 years old, it can get trickier to figure out and may be too late. Guidelines from the American Academy of Pediatrics recommend cholesterol screening for children as young as ten years old for the general population and as young as two years old for families with a history of FH. Current research shows that intervening early has a big impact.

What is the CASCADE FH Registry and why is it important?

To advocate for change, it’s really important to have some numbers to back up what we’re saying. When we publish on the data, it raises the profile of the condition. We also need a baseline to compare to in the future. The beauty of the new CASCADE FH Registry is that we’ll be able to follow patients over time to see if what we are doing is making a difference.

It’s not just important for the individual to know whether they have FH. It’s also important for the family to know. When you identify one person with FH, the real potential benefit comes with screening the rest of the family so you can identify ticking time bombs before they have problems. This is called cascade screening – hence the name of the registry. We want to prevent people with FH from becoming patients with FH. We want to prevent those heart attacks.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

After heart transplant, who survives? New study offers tools to tell

April 20, 2016
Photo by Ms. Phoenix

Photo by Ms. Phoenix

Despite careful patient selection, only about 75 percent of heart recipients survive three years after the transplant surgery. Identifying the patients most in need of additional care has always been tricky, but now Stanford researchers have found a better way to predict which heart transplant recipients have a higher risk of dying or needing another heart transplant, as reported in Circulation today.

One key reason transplant patients die is cardiac allograft vasculopathy, an accelerated and aggressive form of coronary artery disease.

William Fearon, MD, professor of cardiovascular medicine and senior author, explained the significance of their results in a recent email:

Identifying patients at higher risk of dying from cardiac allograft vasculopathy is helpful, because it allows the transplant physicians to be more aggressive with medical therapy and monitoring than they might otherwise be, in order to hopefully prevent adverse events.

The researchers conducted a clinical trial involving seventy-four heart transplant recipients, whose heart physiology was invasively assessed within eight weeks and one year after transplantation. They found that two particular diagnostic procedures were able to successfully identify high-risk recipients — fractional flow reserve and index of microcirculatory resistance.

Fractional flow reserve is a procedure that measures the blood pressure and flow through a specific part of the coronary artery. It is often used to determine whether blood flow is significantly obstructed by a blockage or lesion, guiding a cardiologist’s decision of whether to stent the blockage.

Fearon’s team determined that a low fractional flow reserve measured soon after the transplant independently predicted the heart transplant recipients’ risk of death or retransplantation.

Index of microcirculatory resistance measures the functionality of the tiny vessels that supply blood to the heart, such as capillaries, arterioles and venules. Fearon found that a higher than normal reading measured one year after the heart transplant was also an independent predictor of the recipients’ event-free survival.

The Stanford researchers hope that more emphasis will be placed on these two invasive assessments of cardiac physiology in heart transplant recipients, so their medical regimen can be adjusted to improve the odds of their survival.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Connecting with others is good for your health

April 11, 2016

Just about everyone I know feels overwhelmed with an endless ‘to do’ list of work assignments, chores, errands and appointments. By the end of the day, we often don’t feel up to hitting the gym or going out. We just want to go home to collapse and recharge.

Our busy lives can make it hard to spend much quality time with friends and family. However, research suggests that we need to make this a priority, because social connections impact our health and wellness.

Rosan Gomperts, director of the Faculty Staff Help Center at Stanford, explained the importance of prioritizing relationships in a recent BeWell@Stanford interview:

Many studies show that there are distinct, positive physical and emotional benefits from having supportive social connections. Research suggests that illness rates are lower, as is premature death, for those who are socially connected. What seems eminently clear is that positive, supportive connections help people manage the stress of daily living better than people who do not have the outlet of someone who will listen and empathize with their experience.

Gomperts recommends several ways to expand your social connections, such as joining a book club or knitting club, taking a class or volunteering. The key is to find something that works for you. She explained:

For some people, getting out can be really hard — whether due to depression, social anxiety or a lack of time due to pressures in life. However, finding a way to connect is incredibly important, and there are Internet options that can be very useful.

Some people can also benefit from sharing their sense of isolation, loneliness or desire to have more social connections with a counselor or support group — such as those offered at the Faculty Staff Help Center.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Imaging study shows genetics and environment affect different parts of the brain

April 7, 2016
Photo by AdinaVoicu

Photo by AdinaVoicu

One of the oldest scientific debates is “nature versus nurture” — do inherited traits or environmental factors shape who we are, and what we do?

So far it’s a draw.

For instance, a massive meta-study, reported in Nature Genetics, quantified the heritability of human traits by analyzing more than 50 years of data on almost 18 thousand traits measured in over 14.5 million pairs of twins. They determined that heritability accounted for 49 percent of all traits and environmental influences for 51 percent.

They essentially found that genes and the environment play an equal role in human development. But that isn’t the end of the debate.

Researchers in Osaka University Graduate School of Medicine in Japan have now added a new twist. They used positron emission tomography (PET) to examine how genetics and environmental factors affect the brain, as reported in the March issue of Journal of Nuclear Medicine.

The researchers used PET imaging to measure the glucose — or energy — metabolism throughout the brain. The authors explained their motivation in the JNM article:

“The patterns of glucose metabolism in the brain appear to be influenced by various factors, including genetic and environmental factors. However, the magnitude and proportion of these influences remain unknown.”

The researchers studied 40 identical twin pairs and 18 fraternal twin pairs. Any differences between identical twins is expected to be due to environmental factors since they are genetically identical, whereas fraternal twins only share half the same genes on average.

The researchers compared imaging results between the two types of twins to estimate the extent of genetic and environmental influences. When a genetic influence is dominant, the identical twins would have more trait similarity than fraternal twins. When an environmental influence is dominant, the trait similarity would be the same for identical and fraternal twins.

The researchers found that both genetic and environmental factors influenced glucose metabolism in the brain, but they predominantly affected different areas. Genetic influences played a major role in the left and right parietal lobes and the left temporal lobe, whereas environmental influences were dominant in other regions of the brain.

The brain’s parietal lobes process sensory information such as taste, temperature and touch, and the temporal lobes process sounds and speech comprehension. More research is needed to understand why these areas of the brain where influenced more by genetics.

In addition to adding new information to the “nature verses nurture” debate, these results could be applied to other research areas, such as using imaging to better understand the underlying cause of Alzheimer’s disease or psychiatric disorders. Identifying which regions of the brain are more influenced by genetics or the environment may add critical information to help better understand and treat diseases.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.


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