Smoking, high blood pressure, diabetes and obesity each linked to unhealthy brains
March 11, 2019
Science Daily/European Society of Cardiology
Factors that influence the health of our blood vessels, such as smoking, high blood and pulse pressures, obesity and diabetes, are linked to less healthy brains. The strongest links are with areas of the brain known to be responsible for our more complex thinking skills, and which deteriorate during the development of Alzheimer's disease and dementia.
The study examined the associations between seven vascular risk factors and differences in the structures of parts of the brain. The strongest links were with areas of the brain known to be responsible for our more complex thinking skills, and which deteriorate during the development of Alzheimer's disease and dementia.
The researchers, led by Dr Simon Cox, a senior research associate at the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh (UK), examined MRI scans of the brains of 9,772 people, aged between 44 and 79, who were enrolled in the UK Biobank study -- one of the largest groups of people from the general population to have data available on brain imaging as well as general health and medical information. All had been scanned by a single scanner in Cheadle, Manchester, and most of the participants were from the north-west of England. This is the world's largest single-scanner study of multiple vascular risk factors and structural brain imaging.
The researchers looked for associations between brain structure and one or more vascular risk factors, which included smoking, high blood pressure, high pulse pressure, diabetes, high cholesterol levels, and obesity as measured by body mass index (BMI) and waist-hip ratio. These have all been linked to complications with the blood supply to the brain, potentially leading to reduced blood flow and the abnormal changes seen in Alzheimer's disease.
They found that, with the exception of high cholesterol levels, all of the other vascular risk factors were linked to greater brain shrinkage, less grey matter (tissue found mainly on the surface of the brain) and less healthy white matter (tissue in deeper parts of the brain). The more vascular risk factors a person had, the poorer was their brain health.
Dr Cox said: "The large UK Biobank sample allowed us to take a comprehensive look at how each factor was related to many aspects of brain structure. We found that higher vascular risk is linked to worse brain structure, even in adults who were otherwise healthy. These links were just as strong for people in middle-age as they were for those in later life, and the addition of each risk factor increased the size of the association with worse brain health.
"Importantly, the associations between risk factors and brain health and structure were not evenly spread across the whole brain; rather, the areas affected were mainly those known to be linked to our more complex thinking skills and to those areas that show changes in dementia and 'typical' Alzheimer's disease. Although the differences in brain structure were generally quite small, these are only a few possible factors of a potentially huge number of things that might affect brain ageing."
Smoking, high blood pressure and diabetes were the three vascular risk factors that showed the most consistent associations across all types of brain tissue types measured. High cholesterol levels were not associated with any differences in the MRI scans.
To quantify the size of the differences they observed, Dr Cox explained: "We compared people with the most vascular risk factors with those who had none, matching them for head size, age and sex. We found that, on average, those with the highest vascular risk had around 18ml, or nearly 3%, less volume of grey matter, and one-and-a-half times the damage to their white matter -- the brain's connective tissue -- compared to people who had the lowest risk; 18ml is slightly more than a large tablespoon-full, or a bit less than a small, travel-sized toothpaste tube."
He said that the findings showed the potential of making lifestyle changes to improve brain and cognitive ageing.
"Lifestyle factors are much easier to change than things like your genetic code -- both of which seem to affect susceptibility to worse brain and cognitive ageing. Because we found the associations were just as strong in mid-life as they were in later life, it suggests that addressing these factors early might mitigate future negative effects. These findings might provide an additional motivation to improve vascular health beyond respiratory and cardiovascular benefits."
Limitations of the study include the fact that it does not include people over the age of 79 and that UK Biobank participants tend to live in less deprived areas, which may restrict how the findings can be generalised to other populations. As the researchers were measuring brain structures only, and were not carrying out functional brain imaging or tests of thinking skills, they cannot show in this study how the changes in brain structure might impact cognitive function, but other studies have shown the relationship between increased numbers of vascular risk factors and worse or declining thinking skills, and dementia.
Now the researchers plan to measure the links between vascular risk factors and thinking skills in the UK Biobank participants and in other groups too. In addition, they are following older people, and carrying out multiple scans and tests of thinking skills. They hope this will tell them more about the role that vascular risk factors play in the decline of different types of thinking skills and which areas of the brain are implicated. They also hope that the findings will motivate future work to understand the biological mechanisms through which different sources of vascular risk might be related to different brain areas and tissues.
https://www.sciencedaily.com/releases/2019/03/190311081944.htm
Only 12 percent of American adults are metabolically healthy
Trends help sound alarm for efforts to lower associated risk of types 2 diabetes, heart disease and other complications
November 28, 2018
Science Daily/University of North Carolina at Chapel Hill
The prevalence of metabolic health in American adults is 'alarmingly low,' even among people who are normal weight, according to a new study. Only one in eight Americans is achieving optimal metabolic health. This carries serious implications for public health since poor metabolic health leaves people more vulnerable to developing Type 2 diabetes, cardiovascular disease and other serious health issues.
This study, published Nov. 28 in the journal Metabolic Syndrome and Related Disorders, presents the most updated U.S. data on metabolic health, which is defined as having optimal levels of five factors: blood glucose, triglycerides, high-density lipoprotein cholesterol, blood pressure, and waist circumference, without the need for medications.
For the study, researchers examined National Health and Nutrition Examination Survey data from 8,721 people in the United States between 2009 and 2016 to determine how many adults are at low versus high risk for chronic disease. Data revealed that only 12.2 percent of American adults are metabolically healthy, which means that only 27.3 million adults are meeting recommended targets for cardiovascular risk factors management.
In the last decade the thresholds for common health measures, for example those that are used to determine if someone has high blood pressure or blood sugar levels, have been lowered by respected professional medical societies. These more restrictive guidelines may mean that a smaller proportion of people are meeting the optimal levels for the cardiovascular risk factors.
"The study fills a gap. We wanted to know how many American adults really meet the guidelines for all of these risk factors and are within optimal levels for disease prevention and health," said Joana Araujo, postdoctoral research associate in nutrition and the study's first author. "Based on the data, few Americans are achieving metabolic health, but the most disturbing finding was the complete absence of optimal metabolic health in adults who had obesity, less than a high school education, were not physically active and were current smokers. Our findings should spur renewed attention to population-based interventions and widely accessible strategies to promote healthier lifestyles."
The data showed that being more physically active, female, younger, more educated and a nonsmoker were factors associated with being more metabolically healthy. Whereas, being non-Hispanic black or having a higher body mass index meant people were less likely to be metabolically healthy.
The research team looked at how health-related behaviors might play into metabolic health and how the proportion of people who are metabolically healthy changes when BMI, physical activity or smoking rates are higher or lower. They found that less than 1 percent of obese adults are metabolically healthy. On the other hand, people who exercise more appear to have higher levels of metabolic health.
The authors call for further study to understand the mechanisms of risk factor development, with a focus on people of normal weight as well as heavier adults.
https://www.sciencedaily.com/releases/2018/11/181128115045.htm
Short and long sleep durations lnked with excess heart age
Sleep duration and heart age may be a simplified way to express cardiovascular disease risk
June 4, 2018
Science Daily/American Academy of Sleep Medicine
Preliminary results from a new study show that excess heart age (EHA) appeared to be lowest among adults who reported sleeping seven hours per 24-hour period.
Results show that mean adjusted EHA was lowest among adults who reported sleeping seven hours per 24-hour period. Sleeping times less than or greater than seven hours were associated with increased excess heart age, and the highest elevations in EHA were noted in short sleepers. Sleep duration coupled with EHA may prove helpful for communicating the cardiovascular risks and benefits associated with sleep duration.
"These results are important because they demonstrate a quantitative method for the inclusion of sleep duration in the establishment and communication of cardiovascular risk for individuals. This could have utility in the clinical care of patients with cardiovascular risk, and for public health researchers interested in adding a sleep metric to future studies," said primary researcher and study author Julia Durmer, BS candidate, Emory University, the Center for the Study of Human Health and student researcher, Emory University, Rollins School of Public Heath in Atlanta, Ga.
The study involved 12,775 adults ranging in age from 30-74 years who responded to the 2007-2014 National Health and Nutrition Examination Survey (NHANES). Self-reported sleep duration was classified into five categories (5 or less, 6, 7, 8, and 9 or more hours of sleep per night). They used the sex-specific Framingham heart age algorithm to calculate each individual's heart age and used multivariable linear or logistic regression to examine the association between sleep duration and EHA or risk of EHA 10 years or more.
https://www.sciencedaily.com/releases/2018/06/180604093121.htm
Midlife cardiovascular risk factors may increase chances of dementia
Study supports link between cognition and vascular health
August 7, 2017
Science Daily/NIH/National Institute of Neurological Disorders and Stroke
A large, long-term study suggests that middle aged Americans who have vascular health risk factors, including diabetes, high blood pressure and smoking, have a greater chance of suffering from dementia later in life.
"With an aging population, dementia is becoming a greater health concern. This study supports the importance of controlling vascular risk factors like high blood pressure early in life in an effort to prevent dementia as we age," said Walter J. Koroshetz, M.D., director of NIH's National Institute of Neurological Disorders and Stroke (NINDS), which partially funded the study and created the Mind Your Risks® public health campaign to make people more aware of the link between cardiovascular and brain health. "What's good for the heart is good for the brain," he added.
The study was led by Rebecca Gottesman, M.D., Ph.D., professor of neurology at Johns Hopkins University in Baltimore. Her team analyzed the data of 15,744 people who participated in the Atherosclerosis Risk in Communities (ARIC) study, funded by the NIH's National Heart, Lung, and Blood Institute (NHLBI). From 1987-1989, the participants, who were black or white and 45-64 years of age, underwent a battery of medical tests during their initial examinations at one of four centers in four different states. Over the next 25 years they were examined four more times. Cognitive tests of memory and thinking were administered during all but the first and third exams.
Her team found that 1,516 participants were diagnosed with dementia during an average of 23 follow-up years. Initially, when they analyzed the influence of factors recorded during the first exams, the researchers found that the chances of dementia increased most strongly with age followed by the presence of APOE4, a gene associated with Alzheimer's disease. Whites with one copy of the APOE4 gene had a greater chance of dementia than blacks. Other factors included race and education: blacks had higher chance of dementia than whites; those who did not graduate from high school were also at higher risk.
In agreement with previous studies, an analysis of vascular risk factors showed that participants who had diabetes or high blood pressure, also called hypertension, had a higher chance of developing dementia. In fact, diabetes was almost as strong a predictor of dementia as the presence of the APOE4 gene.
Unlike other studies, the researchers discovered a link between dementia and prehypertension, a condition in which blood pressure levels are higher than normal but lower than hypertension. Also, race did not influence the association between dementia and the vascular risk factors they identified. Diabetes, hypertension and prehypertension increased the chances of dementia for white and black participants. Finally, smoking cigarettes exclusively increased the chances of dementia for whites but not blacks.
"Our results contribute to a growing body of evidence linking midlife vascular health to dementia," said Dr. Gottesman. "These are modifiable risk factors. Our hope is that by addressing these types of factors early, people can reduce the chances that they will suffer from dementia later in life."
Further analysis strengthened the idea that the vascular risk factors identified in this study were linked to dementia. For instance, in order to answer the question of whether having a stroke, which is also associated with the presence of vascular risk factors, may explain these findings, the team reanalyzed the data of participants who did not have a stroke and found similar results. Diabetes, hypertension, prehypertension and smoking increased the risk of dementia for both stroke-free participants and those who had a stroke.
Recently, in a separate study partially funded by the NIH's National Institute on Aging, Dr. Gottesman's team analyzed brain scans from a subgroup of ARIC participants who did not have dementia when they entered the study. They found that the presence of one or more vascular risk factors during midlife was associated with higher levels of beta amyloid, a protein that often accumulates in the brains of Alzheimer's patients. This relationship was not affected by the presence of the APOE4 gene and not seen for risk factors present in later life. The presence of vascular risk factors detected in participants older than 65 years of age during the final examination was not associated with greater levels of beta amyloid.
"With many years of data from a large and diverse population, the ARIC study is a powerful source of information for medical research," said Jacqueline D. Wright, Dr.P.H., program director at NHLBI. "This epidemiologic study aimed to improve our understanding of atherosclerosis and heart disease and, through the investigators' efforts; it has become a great resource for research on dementia and other diseases of aging. The investments in longitudinal cohort studies like ARIC will benefit all of us for many years to come."
In the future, Dr. Gottesman and her team plan to investigate ways in which subclinical, or undiagnosed, vascular problems may influence the brain and why race is associated with dementia.
https://www.sciencedaily.com/releases/2017/08/170807120524.htm