How do I tell if I'm dehydrated?

by Karen Dwyer, The Conversation

Our bodies are pretty good at telling us when we need to drink water. Credit: from www.shutterstock.com

It's a message that's been drummed into us since childhood. Drink water, especially when it's hot, otherwise you'll get dehydrated.

But how do you know if you're dehydrated? Who's more at risk? And what can you do about it?

What's dehydration and why does it matter?

13 jan 2019--When people use the term dehydration, they usually refer to what doctors call "volume depletion" or hypovolaemia.

Volume depletion is a reduction in the volume of water in the blood vessels. But dehydration is quite different and is less common. It's the loss of water from both blood vessels and the body's cells.

Doctors are concerned about volume depletion and dehydration because adequate hydration is required for the body to function normally. Water maintains our body temperature and lubricates our joints. Our body's cells rely on water as does our circulatory, respiratory, gastrointestinal and neurological systems.

Severe cases of volume depletion can lead to shock and collapse. Without resuscitation with fluid, the consequences may be devastating.

Water, water everywhere

A 70kg person is made up of 40L (40kg) is water. Two-thirds of that water is in the cells (intracellular), one-third outside the cells (extracellular).

Outside the cells, 20% of body water is in plasma (around 3L), which together with red bloods cells (2L) gives a total 5L of blood. It's the movement of water between compartments that maintains each one's biochemical composition, allowing your cells and body to work normally.

The total body water volume (water in both the blood vessels and the body's cells) is remarkably constant given the large variation in how much an individual might take in and lose each day.

Water intake is accounted for mostly by how much and what you drink and eat, and the daily variation is regulated by the kidney, which alters your urine output.

The main function of the kidney is to regulate the volume and composition of body fluids within narrow limits by altering output.

When you drink large volumes of fluid, your body can afford to get rid of increased amounts of dilute urine. But when you drink a minimal amount of fluid, your urine is concentrated and you pass only a small volume.

If you're urinating less often than normal, or urinating small volumes of darker coloured urine, it may be time to drink more water.

Other small losses of water include through stool, sweat and lungs.

So if you have diarrhoea or are exercising in the heat, for instance, you will need to drink more fluids.

As fluid is lost from the extracellular compartment such as in cases of diarrhoea and vomiting or bleeding, you can develop symptoms of volume depletion including:

• thirst, including a dry mouth
• dizziness, particularly when standing due to the low blood pressure (a consequence of volume loss)
• and when very severe, confusion (a consequence of inadequate oxygenation of the brain).

Doctors might also note:

• that it takes longer for your skin to bounce back when pinched (known as reduced skin turgor)
• low blood pressure as a reduction in volume directly affects blood pressure
• an increased heart rate, in an attempt by the body to maintain blood pressure
• reduced weight as fluid makes up two-thirds of body weight. A loss of 1L of fluid will read as a drop in 1kg on the scales.

Blood testing will often reveal a degree of kidney impairment. That's because the kidneys require a large blood flow to work normally.

In cases of volume depletion and reduction in blood pressure, blood flow to the kidneys is compromised and they go into a state of "shock". Mostly this is reversible when volume and blood pressure is restored.

As there's no single test for volume depletion, doctors will make a diagnosis after taking a note of your history, examining you and a combination of blood and urine tests.

Here's what happened to Tom

I was on call at the hospital recently when, at 9.45pm on a Sunday, I received a call from the emergency department.

Tom, a 78 year old man, had come in by ambulance after neighbours had found him on his bedroom floor. Tom's cognition was not great at the best of times, and that night he couldn't tell us how long he had been on the floor.

There were no obvious injuries, his blood pressure was low (100/60mmHg), pulse rate high (98 beats per minute) and his temperature was normal. Blood tests showed he had low sodium salt levels and kidney impairment.

Tom had been in the emergency department for six hours by the time the call came to me; in that time he had not passed urine. It all pointed to volume depletion.

We treated Tom with intravenous fluid. He needed 5L over 48 hours, after which he was passing urine again. His blood pressure was back to normal 140/70mmHg, his kidney function had normalised and his weight was up from 46kg on admission to 50kg.

Tom told us he had fallen while getting up at night. He had been on the floor for most of the next day and had not eaten or drunk anything for hours.

Who's most at risk and why?

Some groups are more susceptible to volume depletion, including:

• elderly people like Tom, as our total body water reduces with age and the elderly often have a reduced sensation of thirst. Many older people also have other health problems including chronic kidney disease, which may impact the ability to concentrate urine when the volume is depleted
• babies, because they aren't able to articulate when they're thirsty. They have a higher metabolic rate than adults meaning they require more fluid
• people with impaired thirst mechanisms such as the elderly or people with certain brain injuries
• people losing large volumes of fluid via the bowel (from diarrhoea or through a colostomy)
• people taking medications that promote water loss, in particular diuretics, often referred to as water tablets.

These vulnerable groups need to be aware of the increased risk of volume depletion, minimise their risk by maintaining fluid levels, recognise the symptoms of volume depletion early, and seek prompt treatment, including going to hospital if necessary.

If you experience the symptoms of volume depletion it's important to take heed. At home, start with water if you're thirsty. Once dizziness is present, significant volume loss has ensued and a trip to the doctor is in order. Confusion mandates emergency treatment.

How about physiological dehydration?

Physiological dehydration, which occurs when water is lost from both the blood vessels and from the body's cells compartment, is distinct from volume depletion. But there are many overlapping symptoms, such as thirst, a drop in blood pressure and when severe, confusion.

Dehydration can happen with prolonged and sustained high blood sugar levels as can occur in someone with diabetes. This is because the high sugar levels in the blood pull water out of the cells in an attempt to lower the levels. High sugar levels also make you pass more urine. So in this instance there is loss of fluid from both the intracellular and extracellular compartments.

So for those with diabetes, monitoring blood sugar levels is important. If the bloodsugar is persistently high it's important to seek medical advice to reduce the level safely and prevent dehydration.

In a nutshell

Water is vitally important to the normal function of the body. Volume depletion can occur during anytime of the year, but people are particularly prone over the summer months. The key is prevention and knowing what the signs and symptoms are. So in summer keep your fluids up; talk to your doctor about any medications that may need adjusting (such as diuretics) and keep an eye out for friends, family and neighbours.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Keeping fit: How to do the right exercise for your age

by Julie Broderick, The Conversation

Credit: zhu difeng/Shutterstock

The effect of exercise on health is profound. It can protect you from a range of conditions, including heart disease, type 2 diabetes and some cancers. But the type and amount of exercise you should do changes as you age. To ensure that you are doing the right type of exercise for your age, follow this simple guide.

Childhood and adolescence

12jan 2019--In childhood, exercisehelps control body weight, builds healthy bones and promotes self-confidence and healthy sleep patterns. The government recommends that children should get at least one hour of exercise a day. As a tip:

• Children should try a variety of sports and develop skills, such as swimming and the ability to hit and kick a ball.
• Lots of non–scheduled physical activity is great, too, such as playing in playgrounds.

Exercise habits tend to steadily decline during teen years, particularly in girls. Getting enough exercise promotes a healthy body image and helps manage stress and anxiety. You can also:

Encourage teenagers to keep one team sport, if possible.

For teenagers who are not into team sports, swimming or athletics can be a good way to keep fitness levels up.

In your 20s

You are at your absolute physical peak in your mid-20s, with the fastest reaction times and highest VO2 max – the maximum rate at which the body can pump oxygen to muscles. After this peak, your VO2 max decreases by up to 1% each year and your reaction time slows each year. The good news is that regular physical activity can slow this decline. Building lean muscle mass and bone density at this age helps you retain them in later years.

• Vary your training and keep it fun. Try tag rugby, rowing or boot camp.
• If you are a regular exerciser, get advice from an exercise professional to build "periodisation" into your training regime. This involves dividing your training regime into progressive cycles that manipulate different aspects of training – such as intensity, volume and type of exercise – to optimise your performance and ensure you peak for a planned exercise event, such as a triathlon.

In your 30s

As careers and family life for many intensify in their 30s, it is important that you maintain cardiovascular fitness and strength to slow normal physical decline. If you have a sedentary job, make sure you maintain good posture and break up long periods of sitting by forcing activity into your day, such as routing your printer to another room, climbing a flight of stairs to use the bathroom on another floor, or standing when taking a phone call so you are moving every half an hour where possible.

• Work smart. Try high-intensity interval training. This is where bursts of high-intensity activity, up to 80% of your maximum heart rate, such as sprinting and cycling, are broken up with periods of lower-intensity exercise. This kind of workout is good for the time poor as it can be done in 20 minutes.
• For all women, and especially after childbirth, do pelvic floor exercises, sometimes known as Kegel exercises daily to help prevent incontinence.
• Diversify your exercise programme to keep it interesting. Try boot camp, spin class or yoga.

In your 40s

Most people start to put on weight in their 40s. Resistance exercise is the best way to optimise calorie burning to counteract fat accumulation and reverse the loss of three to eight percent of muscle mass per decade. Ten weeks of resistance training could increase lean weight by 1.4kg, increase resting metabolic rate by 7% and decrease fat weight by 1.8kg.

• Try kettlebells or start a weight-training programme in your gym.
• Take up running, if you don't run already, and don't be afraid to start a more intensive exercise programme. You get more bang for your buck with running versus walking.
• Pilates can be useful to build core strength to protect against back pain, which often starts in this decade.

In your 50s

In this decade, aches and pains may crop up and chronic conditions, such as type 2 diabetes and cardiovascular disease, can manifest. As oestrogen declines in postmenopausal women, the risk of heart disease increases.

• Do strength training twice a week to maintain your muscle mass.
• Weight-bearing exercises, such as walking, is recommended. Walk fast enough so that your breathing rate increases and you break a sweat.
• Try something different. Tai chi can be excellent for balanceand relaxation.

In your 60s

Typically, people accumulate more chronic conditions as they get older, and ageing is a major risk factor for cancer. Maintaining a high level of physical activity can help prevent cancers, such as post-menopausal breast cancer, colon cancer and cancer of the womb, and it reduces the risk of developing chronic conditions, such as heart disease and type 2 diabetes.

Physical activity tends to decline with age, so keep active and try to buck this trend.

• Try ballroom dancing or other forms of dancing; it's a fun and sociable way to exercise.
• Incorporate strength and flexibility exercises twice a week. Aqua-aerobics can be a great way to develop strength using water as resistance.
• Maintain cardiovascular exercise, such as brisk walking.

70s and beyond

Exercise in your 70s and beyond helps prevent frailty and falls, and it's important for your cognitive function. If you have a period of ill health, try to keep mobile, if possible. Strength and fitness can decline rapidly if you are bed bound or very inactive, which can make it hard to get back to previous levels.

• Walk and talk. Instead of inactive visits from family and friends, go for a walk together. It will keep you motivated and boost your health more than solitary exercise.
• Incorporate some strength, balance and cardiovascular exercise in your regime. But get advice from a physiotherapist or other exercise professional, especially if you have several chronic conditions.

The main message is to keep moving throughout your life. Sustained exercise is what benefits health most.

Provided by The Conversation

Diseases through the decades – here's what to look out for in your 40s, 60s, 80s and beyond

by Stephanie Harrison, Azmeraw T. Amare, Jyoti Khadka, Maria Carolina Inacio, Sarah Bray And Tiffany Gill, The Conversation

Achieving and maintaining a healthy weight will set you up for decades of better health. Credit: Sue Zeng

Many diseases develop and become more likely as we age. Here are some of the most common conditions, and how you can reduce your risk of getting them as you clock over into a new decade.

In your 40s

11 jan 2019--Maintaining a healthy weight can reduce the risk of developing arthritis, coronary heart disease, and other common and related conditions, including back pain, type 2 diabetes, stroke, and many cancers. But almost one-third of Australians in their 40s are obese and one in five already have arthritis.

From the age of 45 (or 35 for Aboriginal and Torres Strait Islanders), heart health checks are recommended to assess risk factors and initiate a plan to improve the health of your heart. This may include changing your diet, reducing your alcohol intake, increasing your physical activity, and improving your well-being.

Checks to identify your risk of type 2 diabetes are also recommended every three years from age 40 (or from age 18 for Aboriginal and Torres Strait Islanders).

If you don't already have symptoms of arthritis or if they're mild, this decade is your chance to reduce your risk of the disease progressing. Focus on the manageable factors, like shedding excess weight, but also on improving muscle strength. This may also help to prevent or delay sarcopenia, which is the decline of skeletal muscle tissue with ageing, and back pain.

Most people will begin to experience age-related vision decline in their 40s, with difficulty seeing up close and trouble adjusting to lighting and glare. A baseline eye check is recommended at age 40.

In your 50s

In your 50s, major eye diseases become more common. Among Australians aged 55 and above, age-related macular degeneration, cataracts, diabetes-related eye diseases and glaucoma account for more than 80% of vision loss.

A series of health screenings are recommended when people turn 50. These preventive measures can help with the early detection of serious conditions and optimising your treatment choices and prognosis. Comprehensive eye assessments are recommended every one to two years to ensure warning signs are detected and vision can be saved.

National cancer screening programs for Australians aged 50 to 74, are available every two years for bowel and breast cancer.

To screen for bowel cancer, older Australians are sent a test in the post they can do at home. If the test is positive, the person is then usually sent for a colonoscopy, a procedure in which a camera and light look for abnormalities of the bowel.

In 2016, 8% of people screened had a positive test result. Of those who underwent a colonoscopy, 1 in 26 were diagnosed with confirmed or suspected bowel cancer and one in nine were diagnosed with adenomas. These are potential precursors to bowel cancer which can be removed to reduce your future risk.

To check for breast cancer, women are encouraged to participate in the national mammogram screening program. More than half (59%) of all breast cancers detected through the program are small (less than or equal to 15mm) and are easier to treat (and have better survival rates) than more advanced cancers.

In your 60s

Coronary heart disease, chronic obstructive pulmonary disease(a disease of the lungs that makes breathing difficult), and lung cancer carry the biggest disease burden for people in their 60s.

If you're a smoker, quitting is the best way to improve both your lung and heart health. Using evidence-based methods to quit with advice from a health professional or support service will greatly improve your chances of success.

The build-up of plaques in artery walls by fats, cholesterol and other substances (atherosclerosis) can happen from a younger age. But the hardening of these plaques and narrowing of arteries, which greatly increases the risk of heart disease and stroke, is most likely to occur from age 65 and above.

Exercise protects against atherosclerosis and research consistently shows any physical activity is better than nothing when it comes to heart health. If you're not currently active, gradually build up to the recommended 30 minutes of moderate-intensity exercise on most, preferably all, days.

Other potentially modifiable risk factors for stroke include high blood pressure, a high-fat diet, alcohol consumption, and smoking.

Your 60s is also a common decade for surgeries, including joint replacements and cataract surgery. Joint replacements are typically very successful, but are not an appropriate solution for everyone and are not without risks. After a joint replacement, you'll benefit from physiotherapy, exercise, and maintaining a healthy weight.

The treatment for cataracts is to surgically remove the cloudy lens. Cataract surgery is the most common elective surgery worldwide, with very low complication rates, and provides immediate restoration of lost vision.

In your 70s

Many of the conditions mentioned above are still common in this decade. It's also a good time to consider your risk of falls. Four in ten people in their 70s will have a fall and it can lead to a cascade of fractures, hospitalisations, disability and injury.

Osteoporosis is one cause of falls. It occurs most commonly in post-menopausal women but almost one-quarter of people with osteoporosis are men. Osteoporosis is often known as a silent disease because there are usually no symptoms until a fracture occurs. Exercise and diet, including calcium and vitamin D, are important for bone health.

Older people are also vulnerable to mental health conditions because of a combination of reduced cognitive function, limitations in physical health, social isolation, loneliness, reduced independence, frailty, reduced mobility, disability, and living conditions.

In your 80s and beyond

Dementia is the second most common chronic condition for Australians in their 80s, after coronary heart disease – and it's the most common for people aged 95 and above.

Many people think dementia is a normal part of the ageing process, but around one-third of cases of dementia could be prevented by reducing risk factors such as high blood pressure and obesity at mid-life.

Early diagnosis is important to effectively plan and initiate appropriate treatment options which help people live well with dementia. But dementia remains underdiagnosed.

Around 70% of Australians aged 85 and above have five or more chronic diseases and take multiple medications to manage these conditions. Effective medication management is critical for people living with multiple conditions because medications for one condition may exacerbate the symptoms of a different coexisting condition.Provided by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hormone could slow Alzheimer's progression

by Anne Craig, Queen's University

PET scan of a human brain with Alzheimer's disease. Credit: public domain

Queen's University researcher Fernanda De Felice (Psychiatry), along with co-authors from the Federal University of Rio de Janeiro, have identified an exercise-linked hormone that could slow the progression of Alzheimer's disease. This research was recently published in the high-profile publication, Nature Medicine.

09 jan 2019--The findings show that irisin, a hormone that is boosted by exercise, plays an important role in the brain and that Alzheimer patients carry less of the hormone. This discovery moves scientists one step closer to developing a medication that reproduces the effects of exercise-induced irisin production in the brain.

"In the past few years, researchers from many places around the world have shown that exercise is an effective tool to prevent different forms of dementia such as Alzheimer's" says Dr. De Felice, a researcher in the Centre for Neuroscience Studies at Queen's. "This has led to an intense search for specific molecules that are responsible for the protective actions of exercise in the brain. Because irisin seems to be powerful in rescuing disrupted synapses that allow communication between brain cells and memory formation, it may become a medication to fight memory loss in Alzheimer's disease."

The new research is important, explains Dr. De Felice, because curing dementia is one of the greatest current and future health care challenges. Unfortunately, despite 30 years searching for treatment drugs, there is no effective medication for Alzheimer's disease. She adds it is also important to remember that the vast majority of patients with dementia can be disabled due to other age-related illness (e.g. arthritis, heart disease, obesity, visual problems, and depression). Furthermore, it can be challenging to engage a patient in regular physical activity.

A drug that increases irisin in the brain could be the key.

"It is important to keep in mind that Alzheimer's is a very complex disease and it is truly hard to treat Alzheimer's patients before irreversible damage occurs in their brains. This is because when a patient is diagnosed with Alzheimer's disease, their brain has already been damaged," Dr. De Felice says. "Finding new protective routes, such as the identification of an exercise-linked component, may be an optimal strategy to heal the brain before brain cells die and dementia becomes irreversible."

The next step in Dr. De Felice's research is investigating the most effective way of delivering irisin to the brain.

More information: Mychael V. Lourenco et al. Exercise-linked FNDC5/irisin rescues synaptic plasticity and memory defects in Alzheimer's models, Nature Medicine (2018). DOI: 10.1038/s41591-018-0275-4

Racial differences in Alzheimer's disease unveiled

by Washington University School of Medicine

Credit: CC0 Public Domain

African-Americans may be twice as likely as Caucasian Americans to develop Alzheimer's disease, but nobody knows why because studies investigating the underlying causes of illness have historically drawn from a nearly all-white pool of research participants. Consequently, little is known about how the neurodegenerative disease arises and progresses in people of non-Caucasian backgrounds.

07 jan 2019--Now, a new study from Washington University School of Medicine in St. Louis has identified racial disparities between African-Americans and Caucasians in the level of a key biomarker used to identify Alzheimer's disease. The findings, published Jan. 7 in JAMA Neurology, suggest that tools to diagnose the illness may not as effectively apply to African-Americans. Specifically, the concern is that Alzheimer's may be under-recognized in African-Americans because they typically have lower levels of the brain protein tau—meaning that people might not meet the threshold to be diagnosed when the disease already has begun to develop in their brains.

"If we only study Alzheimer's in Caucasians, we'll only learn about Alzheimer's in Caucasians," said John C. Morris, MD, the Harvey A. and Dorismae Hacker Friedman Distinguished Professor of Neurology. "If we want to understand all the ways the disease can develop in people, we need to include people from all groups. Without a complete understanding of the illness, we're not going to be able to develop therapies that work for all people."

Morris leads the university's Charles F. and Joanne Knight Alzheimer's Disease Research Center (ADRC). When he took over as principal investigator in 1997, Morris launched an initiative to address the lack of knowledge about the disease in people of color, and started by diversifying the center's pool of study participants. At the time, only about 5 percent of people enrolled in memory and cognitive studies at the center were African-American, though they made up 18 percent of the population in the greater St. Louis area. With the guidance of an African-American advisory board led by civil rights activist Norman R. Seay, the ADRC steadily attracted a more representative participant group that allowed researchers to investigate the roots of racial differences in Alzheimer's.

For this study, Morris and colleagues analyzed biological data from 1,215 people, of whom 14 percent, or 173, were African-American. The participants averaged 71 years of age. Two-thirds showed no signs of memory loss or confusion, and the remaining one-third had either very mild or mild Alzheimer's dementia. All participants underwent at least one test for Alzheimer's: a PET scan to detect plaques of toxic amyloid protein in the brain, an MRI scan for signs of brain shrinkage and damage, or a spinal tap to measure levels of key Alzheimer's proteins in the fluid that surrounds the brain and spinal cord.

Analysis of the MRI and PET scans turned up no significant differences between African-Americans and whites. But when the researchers examined the samples of cerebrospinal fluid, they discovered that African-Americans had significantly lower levels of the brain protein tau. Elevated tau has been linked to brain damage, memory loss and confusion, but having lower levels of tau didn't protect African-Americans from those problems. They were just as likely as Caucasians to be cognitively impaired in this study.

"With tau, the pattern was the same in African-Americans and whites—the higher your tau level, the more likely you were cognitively impaired—but the absolute amounts were consistently lower in African-Americans," Morris said. "What this may indicate is that the cutoffs between normal and high levels of tau that were developed by studying whites are probably not accurate for African-Americans and could cause us to miss signs of disease in some people."

This difference was most pronounced in people with the high-risk form of the gene APOE, known as APOE4. Older Caucasians who carry the APOE4 gene variant have a threefold increase in their risk of developing Alzheimer's disease, making it the single strongest genetic risk factor in that group. But previous studies have found that the gene variant has a much weaker effect in African-Americans.

When Morris and colleagues broke down their data by APOE status, they found that African-Americans with the high-risk form of the gene had lower levels of tau than Caucasians who also carried the risky variant. But among people who carried the low-risk forms of the gene, tau levels were similar, regardless of race.

"It looks like the APOE4 risk factor doesn't operate the same in African-Americans as it does in whites," Morris said. "We need to start looking into the possibility that the disease develops in distinct ways in various populations. People may be getting the same illness ­- Alzheimer's disease—via different biological pathways."

A more complete understanding of the ways Alzheimer's can arise could open up new avenues of research to prevent or treat the devastating disease, the researchers said.

"We've been focusing on African-Americans because we have a large African-American community here in St. Louis, but we also need Asian-Americans, Native Americans, Hispanics, everybody to participate in research," Morris said. "I think we'll find we've been missing a lot by having such limited study populations in the past. We need to find out what else is going on, so we can develop better therapies that apply to everyone."

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More information: JAMA Neurology (2019). DOI: 10.1001/jamaneurol.2018.4249

Artificial intelligence can detect Alzheimer's disease in brain scans six years before a diagnosis

by Dana Smith, University of California, San Francisco

A PET scan of the brain of a person with Alzheimer’s disease. Credit: National Institute on Aging

Using a common type of brain scan, researchers programmed a machine-learning algorithm to diagnose early-stage Alzheimer's disease about six years before a clinical diagnosis is made – potentially giving doctors a chance to intervene with treatment.

07 jan 2019--No cure exists for Alzheimer's disease, but promising drugs have emerged in recent years that can help stem the condition's progression. However, these treatments must be administered early in the course of the disease in order to do any good. This race against the clock has inspired scientists to search for ways to diagnose the condition earlier.

"One of the difficulties with Alzheimer's disease is that by the time all the clinical symptoms manifest and we can make a definitive diagnosis, too many neurons have died, making it essentially irreversible," says Jae Ho Sohn, MD, MS, a resident in the Department of Radiology and Biomedical Imaging at UC San Francisco.

In a recent study, published in Radiology, Sohn combined neuroimaging with machine learning to try to predict whether or not a patient would develop Alzheimer's disease when they first presented with a memory impairment – the best time to intervene.

Positron emission tomography (PET) scans, which measure the levels of specific molecules, like glucose, in the brain, have been investigated as one tool to help diagnose Alzheimer's disease before the symptoms become severe. Glucose is the primary source of fuel for brain cells, and the more active a cell is, the more glucose it uses. As brain cells become diseased and die, they use less and, eventually, no glucose.

Other types of PET scans look for proteins specifically related to Alzheimer's disease, but glucose PET scans are much more common and cheaper, especially in smaller health care facilities and developing countries, because they're also used for cancer staging.

Radiologists have used these scans to try to detect Alzheimer's by looking for reduced glucose levels across the brain, especially in the frontal and parietal lobes of the brain. However, because the disease is a slow progressive disorder, the changes in glucose are very subtle and so difficult to spot with the naked eye.

The brain of a person with Alzheimer’s (left) compared with the brain of a person without the disease. Credit: University of California, San Francisco

To solve this problem, Sohn applied a machine learning algorithm to PET scans to help diagnose early-stage Alzheimer's disease more reliably.

"This is an ideal application of deep learning because it is particularly strong at finding very subtle but diffuse processes. Human radiologists are really strong at identifying tiny focal finding like a brain tumor, but we struggle at detecting more slow, global changes," says Sohn. "Given the strength of deep learning in this type of application, especially compared to humans, it seemed like a natural application."

To train the algorithm, Sohn fed it images from the Alzheimer's Disease Neuroimaging Initiative (ADNI), a massive public dataset of PET scans from patients who were eventually diagnosed with either Alzheimer's disease, mild cognitive impairment or no disorder. Eventually, the algorithm began to learn on its own which features are important for predicting the diagnosis of Alzheimer's disease and which are not.

Once the algorithm was trained on 1,921 scans, the scientists tested it on two novel datasets to evaluate its performance. The first were 188 images that came from the same ADNI database but had not been presented to the algorithm yet. The second was an entirely novel set of scans from 40 patients who had presented to the UCSF Memory and Aging Center with possible cognitive impairment.

The algorithm performed with flying colors. It correctly identified 92 percent of patients who developed Alzheimer's disease in the first test set and 98 percent in the second test set. What's more, it made these correct predictions on average 75.8 months – a little more than six years –before the patient received their final diagnosis.

Sohn says the next step is to test and calibrate the algorithm on larger, more diverse datasets from different hospitals and countries.

"I believe this algorithm has the strong potential to be clinically relevant," he says. "However, before we can do that, we need to validate and calibrate the algorithm in a larger and more diverse patient cohort, ideally from different continents and various different types of settings."

If the algorithm can withstand these tests, Sohn thinks it could be employed when a neurologist sees a patient at a memory clinic as a predictive and diagnostic tool for Alzheimer's disease, helping to get the patient the treatments they need sooner.

More information: Yiming Ding et al. A Deep Learning Model to Predict a Diagnosis of Alzheimer Disease by Using 18F-FDG PET of the Brain, Radiology (2018). DOI: 10.1148/radiol.2018180958

Low carb? Low fat? What the latest dieting studies tell us

by Candice Choi

Dish of steak and cheese pasta in Concord, N.H. Two major studies in 2018 provided more fuel for the debate around carbs and fats, yet failed to offer a resolution to the polarizing matter of the best way to lose weight. (AP Photo/Matthew Mead)

Bacon and black coffee for breakfast, or oatmeal and bananas?

07 jan 2019--If you're planning to try to lose weight in 2019, you're sure to find a fierce debate online and among friends and family about how best to do it. It seems like everyone has an opinion, and new fads emerge every year.

Two major studies last year provided more fuel for a particularly polarizing topic—the role carbs play in making us fat. The studies gave scientists some clues, but, like other nutrition studies, they can't say which diet—if any—is best for everyone.

That's not going to satisfy people who want black-and-white answers, but nutrition research is extremely difficult and even the most respected studies come with big caveats. People are so different that it's all but impossible to conduct studies that show what really works over long periods of time.

Before embarking on a weight loss plan for the new year, here's a look at some of what was learned last year.

FEWER CARBS, FEWER POUNDS?

It's no longer called the Atkins Diet, but the low-carb school of dieting has been enjoying a comeback. The idea is that the refined carbohydrates in foods like white bread are quickly converted into sugar in our bodies, leading to energy swings and hunger.

By cutting carbs, the claim is that weight loss will be easier because your body will instead burn fat for fuel while feeling less hungry. A recent study seems to offer more support for low-carb proponents. But, like many studies, it tried to understand just one sliver of how the body works.

The study , co-led by an author of books promoting low-carb diets, looked at whether varying carb levels might affect how the body uses energy. Among 164 participants, it found those on low-carb diets burned more total calories than those on high-carb diets.

The study did not say people lost more weight on a low-carb diet—and didn't try to measure that. Meals and snacks were tightly controlled and continually adjusted so everyone's weights stayed stable.

David Ludwig, a lead author of the paper and researcher at Boston Children's Hospital, said it suggests limiting carbs could make it easier for people to keep weight off once they've lost it. He said the approach might work best for those with diabetes or pre-diabetes.

Ludwig noted the study wasn't intended to test long-term health effects or real-world scenarios where people make their own food. The findings also need to be replicated to be validated, he said.

Caroline Apovian of Boston University's School of Medicine said the findings are interesting fodder for the scientific community, but that they shouldn't be taken as advice for the average person looking to lose weight.

DO I AVOID FAT TO BE SKINNY?

For years people were advised to curb fats , which are found in foods including meat, nuts, eggs, butter and oil. Cutting fat was seen as a way to control weight, since a gram of fat has twice as many calories than the same amount of carbs or protein.

Many say the advice had the opposite effect by inadvertently giving us license to gobble up fat-free cookies, cakes and other foods that were instead full of the refined carbs and sugars now blamed for our wider waistlines.

Nutrition experts gradually moved away from blanket recommendations to limit fats for weight loss. Fats are necessary for absorbing important nutrients and can help us feel full. That doesn't mean you have to subsist on steak drizzled in butter to be healthy.

Bruce Y. Lee, a professor of international health at Johns Hopkins, said the lessons learned from the anti-fat fad should be applied to the anti-carb fad: don't oversimplify advice.

"There's a constant look for an easy way out," Lee said.

SO WHICH IS BETTER?

Another big study this past year found low-carb diets and low-fat diets were about equally as effective for weight loss. Results varied by individual, but after a year, people in both groups shed an average of 12 to 13 pounds.

The author noted the findings don't contradict Ludwig's low-carb study. Instead, they suggest there may be some flexibility in the ways we can lose weight. Participants in both groups were encouraged to focus on minimally processed foods like produce and meat prepared at home. Everyone was advised to limit added sugar and refined flour.

"If you got that foundation right, for many, that would be an enormous change," said Christopher Gardner of Stanford University and one of the study's authors.

Limiting processed foods could improve most diets by cutting down overall calories, while still leaving wiggle room for people's preferences. That's important, because for a diet to be effective, a person has to be able to stick to it. A breakfast of fruit and oatmeal may be filling for one person, but leave another hungry soon after.

Gardner notes the study had its limitations, too. Participants' diets weren't controlled. People were instead instructed on how to achieve eating a low-carb or low-fat in regular meetings with dietitians, which may have provided a support network most dieters don't have.

SO, WHAT WORKS?

In the short term you can probably lose weight by eating only raw foods, or going vegan, or cutting out gluten, or following another diet plan that catches your eye. But what will work for you over the long term is a different question.

Zhaoping Li, director of clinical nutrition division at the University of California, Los Angeles, says there is no single set of guidelines that help everyone lose weight and keep it off. It's why diets often fail—they don't factor into account the many factors that drive us to eat what we do.

To help people lose weight, Li examines her patients' eating and physical activity routines to identify improvements people will be able to live with.

"What sticks is what matters," Li said.

When pets are family, the benefits extend into society

by Lisa F. Carver, The Conversation

In addition to the health benefits of physical activity, walking your dog has many social and community benefits. Credit: Shutterstock

There is a growing global trend to consider pets as part of the family. In fact, millions of people around the world love their pets, enjoying their companionship, going for walks, playing and even talking to them. And there is evidence suggesting that attachment to pets is good for human health and even helps build community.

07 jan 2019--More and more often, animals are included in family events and become important to all members of the family. This can be particularly significant in single-parent families, where a pet can be an important companion to children. Children with pets may have higher levels of empathy and self-esteem compared to those who do not have pets. Thinking of pets as family members can actually make the chores associated with pet care less stressful than they are for those who consider pets as property. Spending more time caring for a pet increases attachment to that animal which in turn reduces stress in owners.

In the research my colleagues and I have done on aging and social participation, we found considerable analysis showing that interactions involving pets, especially if we care about them, can have a health-protective effect. Zooeyia (pronounced zoo-AY-uh) is the idea that pets, also known as companion animals, can be good for human health. In fact, pet owners in Germany and Australia were found to visit their doctor 15 per cent fewer times annually than non-pet owners.

Healthy, emotional connections

Many health benefits to humans occur when there is an emotional attachment to pets. And we tend to care the most for animals that live with us. For example, a study that looked at attachment to dogs found that people tended to care about their house dogs more than those that lived in the yard. Higher levels of attachment to dogs has been associated with a greater likelihood of walking the dog and spending more time on those walks as compared with those with a weaker bond to their dogs.

Sharing your life with a pet has been associated with a decreased risk of coronary artery disease, a reduction in stress levels and increased physical activity (especially through dog walking). The presence of a pet during stressful activities has been shown to lower the blood pressure of couples taking part in a stressful task. In fact, levels of beta-endorphin, oxytocin and dopamine, among other markers, increased in both humans and their dogs during caring interactions, demonstrating that time spent together is physiologically beneficial for both species. And owning a pet has been associated with an improved cardiovascular disease survival among older adults (aged 65 to 84 years old) being treated for hypertension.

Because pets are considered family members by many people, the loss of a dog or cat is often a cause for deep grief. A missing or dead pet is hard for many to replace because the relationship between the person and pet was specific to those individuals. The attachment between humans and animals is often so strong that it is common to mourn in a way that is very similar to the feelings and behaviours associated with the loss of a human family member.

The bond between humans and animals is not just good for human health, it can also help build community. People with pets often find that activities with their companion animal creates connections with other people. Social networks that are developed based on shared concern over the welfare of animals can lead to increased human-human interaction, as well as activities involving pets (e.g. dog-walking clubs). Walking a dog gets people out of private spaces, which can be isolating, and into public areas where interactions with neighbors and other walkers are possible.

Protecting pets

Societies create laws and institutions to protect companion animals from cruelty and neglect. In most jurisdictions, regulation of shelters and pounds has not evolved to reflect the beloved status of many pets, and instead consider pets as property. If a lost pet is not reunited with an owner within a few days it can be sold to a new family, to a research lab, or be euthanized. However, some countries, such as India, Italy and Taiwan have legislated against the euthanasia of healthy shelter animals.

But in North America euthanasia is still common. In 2017, Humane Canada found that among the shelters they surveyed, over 70 per cent of lost dogs and cats were unclaimed, and tens of thousands of dogs and cats were euthanized. In 2016, 4,308,921 animals were experimented on in Canadian laboratories. Approximately 17,000 were pet dogs and cats who were provided by shelters to research laboratories and later euthanized.

The strength of the human-animal bond has resulted in the creation of not-for-profit animal rescues whose mission is to 'pull' lost and abandoned animals from shelters before they are euthanized or sold for research. For example, Marley's Hope is a Nova Scotia all-breed rescue organization. The organisation also partners with the Sipekne'katik First Nation to help rehome roaming dogs as well as spay and neuter where possible. The Underdog Railroad in Toronto, Ontario, rescues dogs and cats from high-kill shelters as well as those offered "free to a good home" online. And Elderdog provides older adults with help to care for their pets as well as rescuing abandoned older dogs.

The Humane Society International —Canada assists in spay-neuter programs as well as advocating for and rescuing animals, including in the international dog and cat meat industries. They closed three South Korean dog meat farms and two slaughterhouses in 2018, rescuing 512 dogs, many of whom found homes in Canada and the USA.

Mohandas Ghandi understood the importance of the human animal bond. In his autobiography he said "man's supremacy over the lower animals meant not that the former should prey upon the latter, but that the higher should protect the lower, and that there should be mutual aid between the two." Recognizing the ways that companion animals enrich human lives, and understanding the depth of the affection between many humans and animals, may be the key to not only better health, but to improving the welfare of society as a whole.

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Provided by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.