Napping may help with blood pressure management

ScienceDaily (Feb. 28, 2011) — A daytime sleep could have cardiovascular benefits according to new research by Ryan Brindle and Sarah Conklin, PhD, from Allegheny College in Pennsylvania in the US. Their study, looking at the effect of a daytime nap on cardiovascular recovery following a stress test, found that those participants who slept for at least 45 minutes during the day had lower average blood pressure after psychological stress than those who did not sleep.

Long work schedules, shift work, increased anxiety and a greater use of the internet and television late at night -- all characteristics of our modern society -- have had an impact on nocturnal sleep. We no longer sleep as long as we used to: The average sleep duration is now almost 2 hours shorter per night than it was 50 years ago. And this could be impacting our long-term health. For example, sleeping less has been linked to an increased risk of hypertension and cardiovascular problems generally.

Brindle and Conklin's experiment examined how daytime sleep might influence cardiovascular recovery after a mental stress test in the laboratory. They split 85 healthy university students into two groups: One group was allotted a 60-minute interval during the day when they had the opportunity to sleep; the other group did not sleep during the day. The researchers also asked the students to complete questionnaires assessing sleep quality and complete a cardiovascular reactivity task, involving a complex mental subtracting exercise. Brindle and Conklin measured the students' blood pressure and pulse rates at regular intervals throughout the experiment.

They found that daytime sleep seemed to have a restorative effect with students in the sleep condition reporting lower scores of sleepiness than those who did not sleep. Although blood pressure and pulse rates rose in both groups between baseline and the stress phase, during the recovery phase, those who had napped had significantly lower average blood pressure readings than those who had not slept. These results show that sleeping between 45 and 60 minutes during the day appears to facilitate blood pressure recovery after a mental stress task in the laboratory.

Brindle and Conklin conclude: "Our findings suggest that daytime sleep may offer cardiovascular benefit by accelerating cardiovascular recovery following mental stressors. Further research is needed to explore the mechanism by which daytime sleep is linked with cardiovascular health and to evaluate daytime sleep as a recuperative and protective practice, especially for individuals with known cardiovascular disease risk and those with suboptimal sleep quality."

The work is published in Springer's journal International Journal of Behavioral Medicine.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Springer Science+Business Media, via AlphaGalileo.

Journal Reference:

Brindle RC and Conklin S. Daytime sleep accelerates cardiovascular recovery after psychological stress. International Journal of Behavioral Medicine, 2011

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Proteins regulating water retention in salt-sensitive hypertension identified

ScienceDaily (Oct. 25, 2010) — Research conducted by scientists at LSU Health Sciences Center New Orleans has found that two proteins in the brain act as valves to turn the hormone that regulates water retention in the body on and off. Their findings may lead to advances in treatment for diseases like high blood pressure, congestive heart failure, and cirrhosis of the liver.

The research is published in the Nov. 1, 2010 issue of Endocrinology.

Daniel Kapusta, PhD, Professor of Pharmacology at LSU Health Sciences Center New Orleans, and Richard Wainford, PhD, LSUHSC Instructor of Pharmacology, report the role of these brain proteins, called Gaq and Gaz, in producing elevated secretion of the hormone, vasopressin, and water retention in salt-sensitive hypertension, a condition in which blood pressure becomes elevated when salt is consumed. It is estimated that salt-sensitive hypertension occurs in about 26% of Americans with normal blood pressure and in 58% of those whose blood pressure is already high.

"Throughout the day, vasopressin, a peptide hormone produced by the hypothalamus, is released into the circulation from the pituitary gland and plays a vital role as the flood-gate keeper to prevent excessive loss of water from the kidneys," notes Dr. Kapusta. "Under most conditions, the water-retaining action of vasopressin is vital for survival. However, it has remained essentially a black box as to why, in susceptible individuals, the regulatory mechanisms that control vasopressin secretion cannot turn off when the body already has elevated water content."

For 21-days, the research team fed groups of male salt-resistant and salt-sensitive rats a diet containing either normal or high salt. Then they measured how the treatments influenced the animal's ability to excrete water and how the salt stress altered levels of vasopressin, Gaq and Gaz.

The consumption of high salt triggered a decrease in Gaq proteins in the brain of salt-resistant, but not salt-sensitive, rats. In salt-sensitive rats, the team demonstrated that reducing brain Gaq proteins returned plasma vasopressin to normal levels, decreased salt-induced water retention, and restored the animal's ability to excrete water.

"Our findings are novel and provide evidence that the Gaq sub-unit proteins in the hypothalamus act as a molecular/cellular switch to control the level of vasopressin secretion," says Dr. Wainford.

The researchers concluded that reducing brain Gaq proteins plays a critical counter-regulatory role in preventing the secretion of too much vasopressin in those with salt-resistance and may represent a new therapeutic target in diseases associated with fluid retention.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Louisiana State University Health Sciences Center, via EurekAlert!, a service of AAAS.

Journal Reference:

R. D. Wainford, D. R. Kapusta. Hypothalamic Paraventricular Nucleus Gaq Subunit Protein Pathways Mediate Vasopressin Dysregulation and Fluid Retention in Salt-Sensitive Rats. Endocrinology, 2010; 151 (11): 5403 DOI: 10.1210/en.2010-0345

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Deep brain stimulation may help hard-to-control high blood pressure

ScienceDaily (Jan. 24, 2011) — Researchers were surprised to discover what may be a potential new treatment for difficult-to-control high blood pressure, according to a case report published in the January 25, 2011, print issue of Neurology®, the medical journal of the American Academy of Neurology.

The report involved one man who received a deep brain stimulator to treat his pain from central pain syndrome that developed after a stroke. Deep brain stimulation uses a surgical implant similar to a cardiac pacemaker to send electrical pulses to the brain.

The 55-year-old man was diagnosed with high blood pressure at the time of the stroke, and his blood pressure remained high even though he was taking four drugs to control it.

While the electrical stimulation did not permanently alleviate his pain, researchers were surprised to see that stimulation decreased his blood pressure enough that he could stop taking all of the blood pressure drugs.

"This is an exciting finding as high blood pressure affects millions of people and can lead to heart attack and stroke, but for about one in 10 people, high blood pressure can't be controlled with medication or they cannot tolerate the medication," said Nikunj K. Patel, BSc MBBS, MD, FRCS, of Frenchay Hospital in Bristol, UK, who wrote the case study.

Patel noted that the decrease in blood pressure was a response to the deep brain stimulation, and not a result of changes to his other conditions.

The man's blood pressure gradually decreased after the deep brain stimulator was implanted in the periaqueductal-periventricular grey region of the brain, which is involved in regulating pain. His blood pressure was controlled for the nearly three years of follow-up; at one point he went back on an anti-hypertension drug for a slight increase in blood pressure, but that drug was withdrawn when the blood pressure went down again.

At one point researchers tested turning off the stimulator. This led to an increase of an average of 18/5 mmHg in blood pressure. When the stimulator was turned back on, blood pressure dropped by an average of 32/12 mmHg. Repeating the tests produced the same results.

"More research is needed to confirm these results in larger numbers of people, but this suggests that stimulation can produce a large, sustained lowering of blood pressure," Patel said. "With so many people not responding to blood pressure medications, we are in need of alternative strategies such as this one."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Academy of Neurology.

Journal Reference:

N.K. Patel, S. Javed, S. Khan, M. Papouchado, A.L. Malizia, A.E. Pickering, J.F.R. Paton. Deep brain stimulation relieves refractory hypertension. Neurology, 2011; 76: 405-407 DOI: 10.1212/WNL.0b013e3182088108

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Population-wide reduction in salt consumption recommended

ScienceDaily (Jan. 14, 2011) — The American Heart Association January 13 issued a call to action for the public, health professionals, the food industry and the government to intensify efforts to reduce the amount of sodium (salt) Americans consume daily.

In an advisory, published in Circulation: Journal of the American Heart Association, the association sets out the science behind the American Heart Association's recommendation for the general population, which is to consume no more than 1500 milligrams (mg) of sodium a day because of the harmful effects of sodium -- elevated blood pressure and increased risk of stroke, heart attacks and kidney disease. Elevated blood pressure (hypertension) is a major public health problem -- approximately 90 percent of all Americans will develop hypertension over their lifetime.

Sodium consumption is currentlymore than two times higher than the recommended upper limit of 1,500 mg daily, with 77 percent of that consumption coming from packaged, processed and restaurant foods. "Even a modest decline in intake -- say 400 mg per day -would produce benefits that are substantial and warrant implementation," say the advisory authors. The 2005 United States Dietary Guidelines for Americans recommended a sodium intake limit of 2,300 mg per day, which many health experts say is too much for most Americans. Earlier this year, the Dietary Guidelines Advisory Committee recommended to the secretaries of the United States Departments of Agriculture (USDA) and U.S. Department of Health and Human Services (HHS) that the goal should be modified to 1,500 mg per day for the general population. The advisory committee consists of leading scientists who reviewed the most recent scientific studies and created a set of recommendations that are being reviewed by the secretaries.

Recently, the American Heart Association lowered their recommendation to no more than 1500 mg of sodium daily for the general public, after a report from the Centers for Disease Control found that a majority of the American population either have high blood pressure or are at high risk for developing it.

According to the advisory:

As sodium intake rises, so does blood pressure and the risk of negative health outcomes.Independent of its effects on blood pressure, excess sodium intake adversely affects the heart, kidneys, and blood vessels.The potential public health benefits of sodium reduction are enormous and extend to all Americans.Scientific evidence on the adverse effects of excess sodium is strong and compellingThe American Heart Association's 2020 impact goals -- to improve the cardiovascular health of all Americans by 20 percent while reducing deaths from cardiovascular diseases and stroke by 20 percent -- include a population-wide reduction of sodium consumption to less than 1,500 mg/daily as one of the ways the association will measure the nation's cardiovascular health. Furthermore, a normal range blood pressure is another key factor the association will use to measure the nation's cardiovascular health status.The American Heart Association is part of the National Salt Reduction Initiative, which is working with the food industry to reduce sodium content in packaged and restaurant food.

Inherent to the negative health effects are rising healthcare costs, the authors add. They point to one recent study that suggests a national effort that reduces sodium intake by 1,200 mg per day should reduce the health burdens related to heart disease in addition to reducing costs by up to $24 billion per year.

"Americans deserve the opportunity to choose how much sodium is in the food they eat. By supporting measures that will reduce sodium in the overall food supply, we are giving consumers freedom to select foods that could allow them to meet sodium recommendations and improve their ideal cardiovascular health," said Ralph Sacco, M.D., president of the American Heart Association.

The American Heart Association advocates for more robust sodium criteria within school nutrition standards, foods advertised and marketed to children and foods purchased by employers or government feeding programs, and for the Secretaries of HHS and USDA to adopt the Dietary Guidelines Advisory Committee recommendations.

The association also supports improved food labeling that helps consumers understand how much sodium is in their diet and consumer education in restaurants to help consumers choose lower-sodium options.

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Gene therapy can reverse pulmonary hypertension, study suggests

ScienceDaily (Oct. 25, 2010) — A Heart and Stroke Foundation researcher has discovered what could be the first truly effective breakthrough in the diagnosis and treatment of pulmonary hypertension, a devastating, life-threatening condition which results in an enlargement of the heart.

"We have discovered an early warning system in a protein called PIM-1," Dr. Sébastien Bonnet told the Canadian Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

Dr. Bonnet has established that the PIM-1 cells can be used as markers of pulmonary hypertension.

"Blood samples were taken from patients to measure PIM-1 expression in the blood," says Dr. Bonnet, who is a professor at Laval University and a researcher at Centre hospitalier universitaire de Québec. "We were surprised to find that the greater the PIM-1 levels, the more severe the pulmonary hypertension in the patient."

He says this opens the doors to using regular blood tests to look at PIM-1 levels. "If there is a slight increase in PIM-1, we will know that something is going on." This is important since the condition is under-diagnosed and often not discovered until it is in a late stage. Without earlier treatment it has a very poor prognosis. The condition has traditionally been diagnosed by a six minute walking test.

PIM-1 also offers the opportunity to move beyond the diagnosis of pulmonary hypertension to treatment. By blocking the PIM-1 protein, researchers were able to reverse the condition.

"This is a remarkable finding," says Dr. Bonnet. "We have found that using gene therapy to inhibit the inappropriate activation of this protein is a novel and effective therapy that can reverse the disease altogether."

Before this discovery there has been no agent to reverse the disease. Current drug treatments can improve quality of life but to this date there has been nothing that can cure the disease.

"Pulmonary hypertension is a rare but life-threatening condition," says Heart and Stroke Foundation spokesperson Dr. Beth Abramson. "These are often very sick individuals. By the time a patient gets to a doctor, the disease is usually well established." Individuals at increased risk of developing pulmonary hypertension include those with a family history and people with a history of blood clots in the lungs (pulmonary embolism).

She recommends that patients pay particular attention to any symptoms like shortness of breath or extreme tiredness. "There are treatments that can help patients live longer, healthier lives."

Pulmonary hypertension is abnormally high blood pressure in the pulmonary arteries, the arteries which carry blood from the heart to the lungs. The condition makes it more difficult for blood to flow to the lungs, causing shortness of breath, fatigue, and swelling of the feet and ankles. It can make everyday tasks almost impossible.

The number of Canadians with pulmonary hypertension is difficult to estimate, because it is under-diagnosed and the early symptoms are common to other conditions such as asthma and general fatigue. In addition, few studies have been conducted.

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Storytelling may help control blood pressure in African-Americans

ScienceDaily (Jan. 18, 2011) — Controlling blood pressure is not only a medical challenge, but a social one as well. Because patients are required to strictly adhere to a treatment plan that may include medication, dietary restrictions and regular doctor visits, the ideas of wellness and health are also powerful parts of the social reinforcement needed for behavioral change.

This is especially true in the African American population, which is particularly susceptible to hypertension. Social and cultural barriers have been found to contribute to African American patients being far more likely than white patients to suffer from uncontrolled high blood pressure and resulting complications.

A new study suggests that a storytelling approach -- in which recognizable members of a community provide positive messages aimed at controlling hypertension through diet and medication adherence -- may offer a unique opportunity to communicate positive disease management choices in a culturally appropriate context.

Researchers at UMass Medical School, working with colleagues at Cooper Green Mercy Hospital and the University of Alabama at Birmingham have identified one promising approach. They identified "exceptionally eloquent and persuasive" patients with hypertension from focus groups where blood pressure control and the benefits of intervention were discussed; these volunteers were then videotaped, and edited DVDs, distilled from 80 hours of taping, were created.

The study appears in the Jan. 18 issue of the Annals of Internal Medicine. Researchers randomly assigned 299 African American patients with hypertension to receive either usual care or to view three videos that presented stories of real patients with hypertension. Among patients who had uncontrolled hypertension, those assigned to view the stories had better blood pressure control than those assigned to usual care -- the first such study that based a health intervention for hypertensive African Americans on positive, culturally sensitive storytelling.

"Overall," the authors wrote, "Among the 300 patients randomized, we found a difference in blood pressure favoring the intervention group, and the significance of this difference was driven by the positive effect among those with uncontrolled blood pressure. Patients with uncontrolled hypertension who were randomized to the intervention group experienced a 10 mmHg advantage in systolic blood pressure reduction relative to control Meaningful advantages were also found for diastolic pressure among the uncontrolled substrata. Blood pressures for both groups subsequently increased over time, but the relative advantage for the intervention group was maintained until the end of follow up."

What accounts for the result? Although there is no direct evidence about the mechanism by which the intervention worked, the researchers believe that the DVDs provided a "parasocial" interaction, one that rendered the viewer of the messages more susceptible to behavior change. "In prior hypertension work, we…translated patient stories into re-enactments using trained actors using high production quality in studio. To maximize [the] para-social interaction [in this study], we enhanced the realism of the current intervention by purposefully avoiding the studio, taping patients in the actual hypertension clinic."

Authors included Thomas K. Houston, MD, MPH, professor of quantitative health sciences and division chief, health informatics and implementation science; Jeroan J. Allison, MD, MSc, vice chair and professor of quantitative health sciences; John Trobaugh, MFA; Yendelela L. Cuffee, MPH; Bruce Barton PhD, research professor of quantitative health sciences; and Catarina I. Kiefe, PhD, MD, professor and chair of quantitative health sciences.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Massachusetts Medical School, via EurekAlert!, a service of AAAS.

Journal Reference:

Houston et al. Culturally Appropriate Storytelling to Improve Blood Pressure: A Randomized Trial. Annals of Internal Medicine, 2011;

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One in four U.S. adults had high blood pressure in 2008

ScienceDaily (Mar. 5, 2011) — More than 59 million Americans age 18 and older were diagnosed with high blood pressure in 2008, according to the latest News and Numbers from the Agency for Healthcare Research and Quality.

AHRQ also found that in 2008:

Three-quarters of people diagnosed with high blood pressure were overweight, obese, or morbidly obese. Roughly 15 percent of healthy weight adults were diagnosed with high blood pressure.Adults who exercised vigorously for 30 minutes or more at least three times a week were one-third less likely than those who didn't to have reported having high blood pressure (21 percent versus 32 percent, respectively).Nearly 32 percent of black adults reported having high blood pressure, compared to 27 percent of white and 18 percent of Hispanic adults.Roughly 29 percent of adults less than 65 years old with public health insurance reported having high blood pressure, versus 19 percent with private insurance and 14 percent of the uninsured.Almost 59 percent of seniors age 65 and older reported having been told they had high blood pressure, compared to nearly 34 percent of people ages 45 to 64, 10 percent of those ages 25 to 44, and almost 3 percent of younger adults.

Statistical Brief: Hypertension in America: Estimates for the U.S. Civilian Noninstitutionalized Population Age 18 and Older, 2008

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E. coli infection linked to long-term health problems

ScienceDaily (Nov. 19, 2010) — People who contract gastroenteritis from drinking water contaminated with E. coli are at an increased risk of developing high blood pressure, kidney problems and heart disease in later life, finds a study published on the British Medical Journal website.

The findings underline the importance of ensuring a safe food and water supply and the need for regular monitoring for those affected.

It is estimated that E. coli O157:H7 infections cause up to 120,000 gastro-enteric illnesses annually in the US alone, resulting in over 2,000 hospitalisations and 60 deaths. However, the long term health effects of E. coli infection in adults are largely unknown.

So a team of researchers in Canada assessed the risk for hypertension, renal impairment and cardiovascular disease within eight years of gastroenteritis from drinking contaminated water.

They used data from the Walkerton Health Study -- the first study to evaluate long term health after an outbreak of gastroenteritis in May 2000 when a municipal water system became contaminated with E. coli O157:H7 and Campylobacter bacteria.

Study participants were surveyed annually and underwent a physical examination and laboratory assessment to track their long term health.

Of 1,977 adult participants, 1,067 (54%) experienced acute gastroenteritis of whom 378 sought medical attention.

Compared with participants who were not ill or only mildly ill during the outbreak, participants who experienced acute gastroenteritis were 1.3 times more likely to develop hypertension, 3.4 times more likely to develop renal impairment, and 2.1 times more likely to have a cardiovascular event, such as a heart attack or stroke.

The authors conclude: "Our findings underline the need for following up individual cases of food or water poisoning by E. coli O157:H7 to prevent or reduce silent progressive vascular injury."

They add: "These long term consequences emphasise the importance of ensuring safe food and water supply as a cornerstone of public health."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by BMJ-British Medical Journal, via EurekAlert!, a service of AAAS.

Journal Reference:

W. F. Clark, J. M. Sontrop, J. J. Macnab, M. Salvadori, L. Moist, R. Suri, A. X. Garg. Long term risk for hypertension, renal impairment, and cardiovascular disease after gastroenteritis from drinking water contaminated with Escherichia coli O157:H7: a prospective cohort study. BMJ, 2010; 341 (nov17 2): c6020 DOI: 10.1136/bmj.c6020

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Short and long sleep in early pregnancy linked to high blood pressure in the third trimester

ScienceDaily (Oct. 2, 2010) — A study in the Oct. 1 issue of the journal Sleep found that getting too little or too much sleep in early pregnancy is associated with elevated blood pressure in the third trimester. The study suggests that improving prenatal sleep hygiene may provide important health benefits.

Results show that the mean systolic blood pressure in the third trimester was 114 mm Hg in women with a normal self-reported nightly sleep duration of nine hours in early pregnancy, 118.05 mm Hg in women who reported sleeping six hours or less per night, and 118.90 mm Hg in women with a nightly sleep duration of 10 hours or more in early pregnancy. After adjustments for potential confounders such as age, race and pre-pregnancy body mass index, mean systolic blood pressure was 3.72 mm Hg higher in short sleepers and 4.21 mm Hg higher in long sleepers. Similar results also were found for diastolic blood pressure.

"Both short and long sleep duration in early pregnancy were associated with increased mean third trimester systolic and diastolic blood pressure values," said principal investigator and lead author Dr. Michelle A. Williams, professor of epidemiology in the School of Public Health at the University of Washington and co-director of the Center for Perinatal Studies at Swedish Medical Center in Seattle, Wash.

The study also found an association between sleep duration and preeclampsia, a condition that involves pregnancy-induced hypertension along with excess protein in the urine. The risk of developing preeclampsia was almost 10 times higher (adjusted odds ratio = 9.52) in very short sleepers who had a nightly sleep duration of less than five hours during early pregnancy. Overall, about 6.3 percent of participants were diagnosed with either preeclampsia or pregnancy-induced hypertension without proteinuria.

"If our results are confirmed by other studies, the findings may motivate increased efforts aimed at exploring lifestyle approaches, particularly improved sleep habits, to lower preeclampsia risk," said Williams.

According to the National Heart, Lung, and Blood Institute, systolic blood pressure -- the top number in a blood pressure reading -- is the force of blood in the arteries as the heart beats. A systolic blood pressure reading is considered to be "high" if it is 140 or more millimeters of mercury.

The Eunice Kennedy Shriver National Institute of Child Health and Human Development reports that preeclampsia is a syndrome that occurs after the 20th week of pregnancy. It should be monitored closely by a medical professional because it can have a severe impact on the health of the mother and her baby.

The study involved 1,272 healthy, pregnant women who completed a structured interview at 14 weeks gestation, on average. Sleep duration in early pregnancy was evaluated by the question, "Since becoming pregnant, how many hours per night do you sleep?" Only about 20.5 percent of women reported a sleep duration of nine hours per night, which was used as the "normal" reference category because prior research indicates that pregnant women tend to have longer sleep duration patterns. About 55.2 percent of women reported sleeping seven to eight hours per night, 13.7 percent slept six hours or less and about 10.6 percent slept 10 hours or more.

After delivery, data on maternal blood pressures at routine prenatal care visits were abstracted from participants' medical records, providing an average of 12 blood pressure values for each participant. Women with pre-gestational chronic hypertension were excluded from the study. Mean systolic blood pressures were 111.8 mm Hg and 111.4 mm Hg in the first and second trimesters, and 114.1 mm Hg in the third trimester.

According to the authors, a number of mechanisms by which habitual short sleep duration may lead to increased blood pressure have been proposed. Because blood pressure is known to dip by an average of 10 to 20 percent during sleep, short sleep durations may raise the average 24-hour blood pressure and heart rate. This may lead to structural changes that gradually raise the pressure equilibrium of the entire cardiovascular system. Sleep restriction also may produce abnormalities in the levels of hormones such as endothelin and vasopressin, which play an important role in the cardiovascular system. The authors suspect that the association between long sleep duration and elevated blood pressures may be related to unmeasured confounders such as obstructive sleep apnea, depression or insulin resistance.

Williams noted that this study is the first step at filling an important gap in the scientific literature. Because most sleep studies exclude pregnant women, little is known about how insufficient sleep during gestation contributes to increased risks of medical complications of pregnancy.

"Moving forward, large-scale sleep studies should include pregnancy cohorts so that health care providers and mothers-to-be can more fully appreciate the health risks of insufficient sleep," she said.

Williams advises pregnant women and women who are planning to become pregnant to develop healthy habits that promote sufficient sleep. The tips she suggested include:

Establishing a consistent sleep scheduleFollowing a relaxing bedtime routineCreating a comfortable sleep environmentKeeping technological distractions such as the TV and computer out of the bedroomEating at least two to three hours before bedtimeExercising regularly during the dayAvoiding caffeine and alcohol before bedtime and giving up smoking

The study was supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Academy of Sleep Medicine, via EurekAlert!, a service of AAAS.

Journal Reference:

Michelle A. Williams et al. Associations of early pregnancy sleep duration with trimester-specific blood pressures and hypertensive disorders in pregnancy. Sleep, (in press)

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New study singles out factors linked to cognitive deficits in type 2 diabetes

ScienceDaily (Sep. 11, 2010) — Older adults with diabetes who have high blood pressure, walk slowly or lose their balance, or believe they're in bad health, are significantly more likely to have weaker memory and slower, more rigid cognitive processing than those without these problems, according to a new study published by the American Psychological Association.

These three health factors stood out from more than a dozen suspected to shape how Type 2 diabetes is frequently shadowed by cognitive impairment, including dementia. An analysis in September's Neuropsychology stresses that although these factors might not actually cause cognitive problems, their presence can warn doctors that such problems may exist or soon develop.

"Awareness of the link between diabetes and cognition could help people realize how important it is to manage this disease--and to motivate them to do so," said co-author Roger Dixon, PhD, of the University of Alberta.

Type 2 diabetes has been found by other researchers to nearly double the risk of dementia and Alzheimer's disease, said Dixon, who studies how health affects cognition in aging. As diabetes becomes more common, this heightened risk could dramatically hike the number of older people with dementia -- a double whammy of serious chronic disease. Among people older than 60, the U.S. prevalence of Type 2 diabetes is more than 23 percent, according to the National Institute of Diabetes and Digestive & Kidney Diseases. The Canadian prevalence is nearly 19 percent, according to the Public Health Agency of Canada.

An analysis of older Canadians living in British Columbia -- 41 with Type 2 diabetes (ages 55-81) and 458 matched healthy controls (ages 53-90) -- found that systolic blood pressure (the top number, or maximum pressure on artery walls during a single heartbeat), a low combination score for gait and balance, and a patient's own reports of poor health all played a statistically significant role in the relationship between diabetes and cognitive impairment relationship.

In other words, higher but still normal blood pressure, slower gait and shakier balance, and/or reporting one's self to be in bad health regardless of actual problems boosted the likelihood that someone with Type 2 diabetes had impaired cognition. The relationships were linear: For example, the worse the balance, the higher the likelihood of cognitive problems, as measured by mental speed (reaction time, switching time and perceptual speed), mental control and flexibility (executive functioning), and recall of recent learning (episodic memory).

The results highlight factors that may work indirectly, gradually and cumulatively to make older diabetics more likely to develop dementia. Researchers tested 13 different variables in all, in the areas of general fitness, emotional health, subjective and functional health, and lifestyle activities.

Mediating Factors

Because diabetes and hypertension often go together, Dixon said he was not surprised that high systolic blood pressure accounted for one-third to one-half of significantly worse scores on four tests. That finding, said the authors, suggests that diabetes and cognition may be connected via diabetics' vascular problems. For example, diabetes and hypertension may both play a role in a larger metabolic syndrome that includes high blood sugar and insulin resistance.

However, the other two factors raised new questions. Combined gait and balance had the greatest influence, accounting for between 32 percent and 62 percent of performance on seven cognitive tests. Diabetes might affect the specific nerves that control gait and balance, the authors wrote, or more broadly affect the overlapping brain areas that support both gait-balance and cognition.

Like blood pressure, what people said about their health accounted for about one-third to one-half of performance on five different cognitive tests. Negativity about one's health could reflect related factors such as stress or depression, which did not, in this study, directly mediate between diabetes and cognition. Self-reported health is "an important indicator of ways in which a cluster of health-related beliefs and behaviors can modulate the effect of this disease on cognitive adaptation," Dixon said.

"It's important to pay attention to the health beliefs of older adults, not because they are necessarily accurate or valid indicators of specific health status, but because they might track overall health," Dixon said.

Type 2 diabetes in adults accounts for 90 percent to 95 percent of all diagnosed cases of diabetes, according to the National Institute of Diabetes and Digestive & Kidney Diseases.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Psychological Association, via EurekAlert!, a service of AAAS.

Journal Reference:

McFall et al. Testing covariates of Type 2 diabetes-cognition associations in older adults: Moderating or mediating effects? Neuropsychology, 2010; 24 (5): 547 DOI: 10.1037/a0019246

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