Could Cholesterol Help Drive Alzheimer’s Disease?

Cholesterol made in the brain may spur development of Alzheimer’s disease, a new study suggests.

Cholesterol made by cells called astrocytes is needed for controlling production of amyloid beta, a sticky protein that builds up in the brain and accumulates into the plaques that are the tell-tale sign of Alzheimer’s.

Researchers say these new findings may offer insight into how and why plaques form and may help explain why genes tied with cholesterol have been linked to increased Alzheimer’s risk.

“This study helps us to understand why genes linked to cholesterol are so important to the development of Alzheimer’s disease,” said study co-author Dr. Heather Ferris, an assistant professor at the University of Virginia School of Medicine.

“Our data point to the importance of focusing on the production of cholesterol in astrocytes and the transport to neurons as a way to reduce amyloid beta and prevent plaques from ever being formed,” she said in a university news release.

Researchers found that astrocytes contribute to Alzheimer’s progression by making cholesterol and sending it to neurons. This cholesterol buildup increases amyloid beta production and, in turn, fuels plaque accumulation, according to the authors.

They found that blocking cholesterol production decreases amyloid beta production in mice. It’s too soon to say if this could happen in people and prevent plaque formation, they said.

“If we can find strategies to prevent astrocytes from over-producing cholesterol, we might make a real impact on the development of Alzheimer’s disease,” Ferris said.

“Once people start having memory problems from Alzheimer’s disease, countless neurons have already died,” she added. “We hope that targeting cholesterol can prevent that death from ever occurring in the first place.”

Source: HealthDay

Eating Walnuts Daily Lowered Bad Cholesterol and May Reduce Cardiovascular Disease Risk

Eating about ½ cup of walnuts every day for two years modestly lowered levels of low-density lipoprotein (LDL) cholesterol, known as “bad cholesterol,” and reduced the number of total LDL particles and small LDL particles in healthy, older adults, according to new research published today in the American Heart Association’s flagship journal Circulation.

Walnuts are a rich source of omega-3 fatty acids (alpha-linolenic acid), which have been shown to have a beneficial effect on cardiovascular health.

“Prior studies have shown that nuts in general, and walnuts in particular, are associated with lower rates of heart disease and stroke. One of the reasons is that they lower LDL-cholesterol levels, and now we have another reason: they improve the quality of LDL particles,” said study co-author Emilio Ros, M.D., Ph.D., director of the Lipid Clinic at the Endocrinology and Nutrition Service of the Hospital Clínic of Barcelona in Spain. “LDL particles come in various sizes. Research has shown that small, dense LDL particles are more often associated with atherosclerosis, the plaque or fatty deposits that build up in the arteries. Our study goes beyond LDL cholesterol levels to get a complete picture of all of the lipoproteins and the impact of eating walnuts daily on their potential to improve cardiovascular risk.”

In a sub-study of the Walnuts and Healthy Aging study, a large, two-year randomized controlled trial examining whether walnuts contribute to healthy aging, researchers evaluated if regular walnut consumption, regardless of a person’s diet or where they live, has beneficial effects on lipoproteins.

This study was conducted from May 2012 to May 2016 and involved 708 participants between the ages of 63 and 79 (68% women) who were healthy, independent-living adults residing in Barcelona, Spain, and Loma Linda, California.

Participants were randomly divided into two groups: active intervention and control. Those allocated to the intervention group added about a half cup of walnuts to their usual daily diet, while participants in the control group abstained from eating any walnuts. After two years, participants’ cholesterol levels were tested, and the concentration and size of lipoproteins were analyzed by nuclear magnetic resonance spectroscopy. This advanced test enables physicians to more accurately identify lipoprotein features known to relate to the risk of cardiovascular disease.

The two-year study had a 90% retention rate (632 participants completed the study). Complete lipoprotein analyses were available in 628.

Among key findings of all study participants:

  • At 2 years, participants in the walnut group had lower LDL cholesterol levels – by an average of 4.3 mg/dL, and total cholesterol was lowered by an average of 8.5 mg/dL.
  • Daily consumption of walnuts reduced the number of total LDL particles by 4.3% and small LDL particles by 6.1%. These changes in LDL particle concentration and composition are associated with a lower risk of cardiovascular disease.
  • Intermediate Density Lipoprotein (IDL) cholesterol also decreased. It is known that IDL cholesterol is a precursor to LDL and refers to a density between that of low-density and very-low-density lipoproteins. In the last decade, IDL cholesterol has emerged as a relevant lipid cardiovascular risk factor independent of LDL cholesterol.
  • LDL cholesterol changes among the walnut group differed by sex; in men, LDL cholesterol fell by 7.9% and in women by 2.6%.

“While this is not a tremendous decrease in LDL cholesterol, it’s important to note that at the start of the study all our participants were quite healthy, free of major non-communicable diseases. However, as expected in an elderly population, close to 50% of participants were being treated for both high blood pressure and hypercholesterolemia. Thanks in part to statin treatment in 32%, the average cholesterol levels of all the people in our study were normal,” Ros said. “For individuals with high blood cholesterol levels, the LDL cholesterol reduction after a nut-enriched diet may be much greater.”

“Eating a handful of walnuts every day is a simple way to promote cardiovascular health. Many people are worried about unwanted weight gain when they include nuts in their diet,” Ros said. “Our study found that the healthy fats in walnuts did not cause participants to gain weight.”

The major limitation of this investigation is that both participants and researchers knew who was and was not eating walnuts. However, the study did involve two very different populations with distinct diets. “The outcomes were similar in both groups, so we can safely apply the results of this study to other populations,” Ros said. More research is also needed to clarify the different LDL results in men and women.

According to the American Heart Association, walnuts are especially high in omega-3 fatty acids, the same heart-healthy fat found in oily fish. A serving size is a small handful or 1.5 ounces of whole nuts or 2 tablespoons of nut butter.

Source: American Heart Association

“Prescription” to Sit Less, Move More Advised for Mildly High Blood Pressure & Cholesterol

A “prescription” to sit less and move more is the optimal first treatment choice for reducing mild to moderately elevated blood pressure and blood cholesterol in otherwise healthy adults, according to the new American Heart Association scientific statement published today in the American Heart Association’s journal Hypertension.

“The current American Heart Association guidelines for diagnosing high blood pressure and cholesterol recognize that otherwise healthy individuals with mildly or moderately elevated levels of these cardiovascular risk factors should actively attempt to reduce these risks. The first treatment strategy for many of these patients should be healthy lifestyle changes beginning with increasing physical activity,” said Bethany Barone Gibbs, Ph.D., FAHA, chair of the statement writing group and associate professor in the department of health and human development and clinical and translational sciences at the University of Pittsburgh in Pittsburgh, Pennsylvania.

An estimated 21% of U.S. adults, about 53 million, have systolic (top number) blood pressure between 120-139 mm Hg or diastolic (bottom number) blood pressure between 80-89 mm Hg; both values are abnormally high. Individuals in this range who have an otherwise low risk of heart disease or stroke meet the American College of Cardiology (ACC)/American Heart Association (AHA) High Blood Pressure Guideline criteria for lifestyle-only treatment for elevated blood pressure.

Likewise, the scientific statement authors estimate that 28% of U.S. adults, or about 71 million, have an LDL cholesterol score above 70 mg/dL and otherwise meet criteria for low risk of heart disease or stroke. These people would meet the 2018 AHA/ACC Cholesterol Treatment Guidelines criteria for lifestyle-only treatment. Lifestyle changes highlighted in the blood pressure and cholesterol guidelines include increased physical activity, weight loss, improving diet, stopping smoking and moderating alcohol intake.

“Increasing physical activity can help lower blood pressure and cholesterol, along with many other health benefits.” Gibbs said. Physical activity also has benefits beyond cardiovascular health, including a decreased risk of some cancers, improved bone, brain and mental health, and better sleep.

Increasing physical activity results in clinically meaningful reductions in systolic and diastolic blood pressure, typically an average reduction of 3 or 4 mm Hg. Similar improvements are seen with blood cholesterol. For example, increased physical activity typically decreases LDL cholesterol by 3 to 6 mg/dL.

The statement highlights research concluding that physically active people have a 21% lower risk of developing cardiovascular disease and a 36% lower risk of death from cardiovascular diseases compared to those who are not physically active.

To improve health, the U.S. Department of Health and Human Services 2018 Physical Activity Guidelines for Americans suggest individuals participate in either a cumulative 150 minutes of moderate intensity aerobic exercise, or 75 minutes of vigorous aerobic activity weekly plus two or more strength training sessions each week.

However, there is no minimum amount of time to receive benefits from physical activity. “Every little bit of activity is better than none,” said Gibbs. “Even small initial increases of 5 to 10 minutes a day can yield health benefits.”

The statement provides suggestions for clinicians to provide exercise “prescriptions” such as patient counselling, incorporating health behavior professionals (e.g., health coaches) and connecting patients to local resources like community centers to help meet their physical activity needs.

According to the statement, prescribing exercise includes:

  • Screening patients about physical activity at every interaction, as recommended by the American College of Sports Medicine’s ‘Exercise is Medicine’ campaign. Clinicians can ask patients to report their physical activity with a few questions or by using a wearable device.
  • Providing ideas and resources for supporting patients to improve and sustain regular physical activity;
  • Meeting patients where they are by exploring activities that the patient enjoys and provide ideas for early success; and
  • Encouraging and celebrating small increases in physical activity, such as walking more or taking the stairs.

“In our world where physical activity is increasingly engineered out of our lives and the overwhelming default is to sit – and even more so now as the nation and the world is practicing quarantine and isolation to reduce the spread of coronavirus – the message that we must be relentless in our pursuit to ‘sit less and move more’ throughout the day is more important than ever,” said Gibbs.

Source: American Heart Association

Managing Children’s Weight, Blood Pressure & Cholesterol Protects Brain Function Mid-life

Managing weight, blood pressure and cholesterol in children may help protect brain function in later life, according to new research published in the American Heart Association’s flagship journal Circulation. This is the first study to highlight that cardiovascular risk factors accumulated from childhood through mid-life may influence poor cognitive performance at midlife.

Previous research has indicated that nearly 1 in 5 people older than 60 have at least mild loss of brain function. Cognitive deficits are known to be linked with cardiovascular risk factors, such as high blood pressure, obesity, type 2 diabetes, smoking, physical inactivity and poor diet, as well as depression and low education level.

Many diseases that cause neurological deficits, such as Alzheimer’s, have a long preclinical phase before noticeable symptoms begin, so finding links between childhood obesity and other cardiovascular risk factors is important for cognitive health. The researchers noted that there are currently no cures for major causes of dementia, so it is important to learn how early in life cardiovascular risk factors may affect the brain.

“We can use these results to turn the focus of brain health from old age and midlife to people in younger age groups,” said the study’s first author Juuso O. Hakala, M.D., a Ph.D. student at the Research Centre of Applied and Prevention Cardiovascular Medicine at the University of Turku, in Turku, Finland. ”Our results show active monitoring and prevention of heart disease and stroke risk factors, beginning from early childhood, can also matter greatly when it comes to brain health. Children who have adverse cardiovascular risk factors might benefit from early intervention and lifestyle modifications.”

The Cardiovascular Risk in Young Finns Study is a national, longitudinal study on cardiovascular risk from childhood to adulthood in Finland. Researchers followed the participants’ cardiovascular risk factor profiles for 31 years from childhood to adulthood. Baseline clinical examinations were conducted in 1980 on approximately 3,600 randomly selected boys and girls, ranging in ages from 3 to 18, all of whom were white. More than 2,000 of the participants, ranging in ages from 34 to 49, underwent a computerized cognitive function test in 2011. The test measured four different cognitive domains: episodic memory and associative learning; short-term working memory; reaction and movement time; and visual processing and sustained attention.

Researchers found:

  • Systolic blood pressure, total blood cholesterol and low-density lipoprotein (LDL) cholesterol, as well as body mass index, from childhood to midlife are associated with brain function in middle age.
  • Consistently high systolic blood pressure or high blood total cholesterol and LDL cholesterol were linked to worse memory and learning by midlife when compared with lower measures.
  • Obesity from childhood to adulthood was associated with lower visual information processing speed and maintaining attention.
  • Having all three cardiovascular risk factors was linked to poorer memory and associative learning, worse visual processing, decreased attention span, and slower reaction and movement time.

These results are from observational findings, so more studies are needed to learn whether there are specific ages in childhood and/or adolescence when cardiovascular risk factors are particularly important to brain health in adulthood. Study limitations include that a definite cause-and-effect link between cardiovascular risk factors and cognitive performance cannot be determined in this type of population-based study; cognition was measured at a single point in time; and because all study participants are white, the results may not be generalizable to people from other racial or ethnic groups.

Source: American Heart Association

Not All “Good” Cholesterol is Healthy

HDL cholesterol (high-density lipoprotein cholesterol) or good cholesterol is associated with a decreased risk of cardiovascular disease as it transports cholesterol deposited in the arteries to the liver to be eliminated. This contrasts with the so-called bad cholesterol, LDL (low-density lipoprotein cholesterol), which causes cholesterol to accumulate in the arteries and increases cardiovascular risk. Although drugs that lower bad cholesterol reduce cardiovascular risk, those that raise good cholesterol have not proven effective in reducing the risk of heart disease. This paradox has called into question the relationship between good cholesterol and cardiovascular risk, and researchers are now studying the characteristics of these HDL or good cholesterol particles.

A study led by the Hospital del Mar Medical Research Institute (IMIM), published in the journal Metabolism, Clinical and Experimental, has now demonstrated that not all good cholesterol is healthy. Researchers from the CIBER on Cardiovascular Diseases (CIBERCV), the CIBER on Obesity and Nutrition (CIBEROBN), and the CIBER on Epidemiology and Public Health (CIBERESP), as well as others from Hospital Clínic-IDIBAPS, IDIBELL, the Hospital de la Santa Creu i Sant Pau Research Institute, and the Hospital Clínico Universitario in Zaragoza also took part in this study.

In the work, the researchers analysed genetic characteristics that determine the size of good cholesterol particles, and then studied their relationship with the risk of myocardial infarction. The conclusion is that genetic characteristics linked to the generation of large good cholesterol particles are directly associated with a higher risk of heart attack, while features linked to small good cholesterol particles are related to a lower risk of heart attack. “There is a positive causal relationship between the size of HDL cholesterol particles and the risk of heart attack, so although we have to increase the levels of good cholesterol in the blood, they must always be small particles”, explains the study’s principal investigator, Dr. Robert Elosua, a researcher at the Hospital del Mar-IMIM, CIBERCV, and the University of Vic-Central University of Catalonia (UVic-UCC).

The good cholesterol particles are more effective in transferring cholesterol to the liver so that it can be eliminated. “If we need to do something in relation to HDL, it is to increase the number of small particles, which are those that adequately perform the function of eliminating cholesterol, those that really move it to the liver for removal, and do not allow it to accumulate in the arteries and cause cardiovascular disease”, says Dr. Álvaro Hernáez, a IDIBAPS and CIBEROBN researcher.

Currently, there are no drugs that increase good cholesterol levels and reduce the risk of cardiovascular disease. “This study highlights new and potential therapeutic targets in the field of cardiovascular diseases, including several genes related to the qualitative aspects of HDL particles, which may contribute to cardiovascular prevention”, concludes Dr. Albert Prats, a researcher in the Epidemiology and Cardiovascular Genetics Research Group at the Hospital del Mar-IMIM and first author of the study.

Source: EurekAlert!