Can dehydration cause depression

6 Conditions That Feel Like Clinical Depression But Aren’t

If a person went to his primary care physician and complained of symptoms of fatigue, guilt, worthlessness, irritability, insomnia, decreased appetite, loss of interest in regular activities, persistent sadness, anxiety, and thoughts of suicide, I am pretty sure he would leave that office with a diagnosis of Major Depression Disorder (MDD) and a prescription for sertraline (Zoloft), fluoxetine (Prozac), or another popular Selective Serotonin Reuptake Inhibitor (SSRI).

After all, the guy has just cataloged the classic symptoms of clinical depression. However, those same symptoms belong to a variety of other conditions, as well, that require treatments other than antidepressants and psychotherapy, the two pillars of conventional psychiatric recovery today. They may certainly look and feel like clinical depression to the outsider, but they may require just a small tweak in diet or hormones. Here are six conditions that fall under that category.

1. Vitamin D Deficiency

A good doctor will order blood work to see if a patient is low on vitamin D before sending him off with a prescription for fluoxetine (Prozac) because so many of us are lacking adequate amounts of this critical vitamin. In fact, according to a 2009 study published in the Archives of Internal Medicine, as many as three-quarters of U.S. teens and adults are deficient. Last year Canadian researchers performed a systematic review and analysis of 14 studies that revealed a close association between vitamin D levels and depression. Researchers found that low levels of vitamin D corresponded to depression and increased odds for depression.

The best source of vitamin D is sunshine, but for those of us with family histories of skin cancer, we have to get it in small doses because sunscreens prohibit the body from making vitamin D. Supplements are easy to find, but make sure they are third-party tested. Good brands are Prothera, Pure Encapsulations, Douglas Labs, and Vital Nutrients. I take drops of liquid vitamin D because it is absorbed more easily that way.

2. Hypothyroidism

Another easily mistaken condition for clinical depression is hypothyroidism. You feel exhausted, worthless, irritable, and incapable of making a decision. Getting through each day without naps is a major accomplishment. This one is especially tricky because you can get your thyroid levels checked by an endocrinologist or primary care physician, as I have done for eight years, and walk away believing your thyroid is just fine.

Dena Trentini writes a brilliant blog about this on her site, Hypothyroid Mom. One of the problems, she explains, is that mainstream medicine relies on only one blood test, TSH, to diagnose thyroid dysfunction and that can’t provide an accurate picture. Both she and I were told our thyroids were fine by conventional doctors, which is probably why the Thyroid Federal International estimates there are up to 300 million people worldwide suffering from thyroid dysfunction, but only half are aware of their condition. Dena writes, “Hypothyroidism, an underactive thyroid, is one of the most undiagnosed, misdiagnosed, and unrecognized health problems in the world.”

3. Low Blood Sugar

The best marriage advice I ever received was this: when you are about to say something unkind to your spouse, first check to see if you’re hungry.

Naturopathic doctor Peter Bongiorno explains the mood-blood sugar connection in his informative blog post, “Is There a Sugar Monster Lurking Within You?” Hunger, he says, is a primitive signal known to set off the stress response in us. For people who are predisposed to anxiety and depression, that stress manifests itself as mood changes. “Triggered by drops and fluctuations in blood sugar,” writes Bongiorno, “anxiety and depression can manifest in people who are very sensitive and can become chronic if food intake isn’t consistent. Humans are built like all the other animals — and animals get very unhappy when blood sugar is low.”

Folks who experience yo-yo blood sugar levels on a daily basis are usually insulin resistant, a precursor to diabetes type II. The Journal of Orthomolecular Medicine shows 82 studies that link insulin resistance with depression. One study of 1,054 Finnish military male conscripts found that moderate-to-severe depressive symptoms increased the risk for insulin resistance by almost three times. The good news is that with some simple diet modifications — eating low-carb, high-protein foods every few hours — symptoms abate.

4. Dehydration

I forgot about this one until my son exhibited some bizarre behavior last night and my husband and I realized he was dehydrated. We go through this every summer. The problem with him (and with most human beings) is that he waits until he is thirsty to drink. By then dehydration has already set in. According to two studies conducted at the University of Connecticut’s Human Performance Laboratory, even mild dehydration can alter a person’s mood.

“Our thirst sensation doesn’t really appear until we are 1 or 2 percent dehydrated. By then dehydration is already setting in and starting to impact how our mind and body perform,” explained Lawrence E. Armstrong, one of the studies’ lead scientists and an international expert on hydration. Apparently it didn’t matter if a person had just walked for 40 minutes on a treadmill or was sitting at rest, the cognitive effects from mild dehydration were the same.

5. Food Intolerances

Like most people, I used to think that food intolerance caused unpleasant reactions like diarrhea, hives, or swelling. I would never have associated a turkey sandwich with my suicidal thoughts. However, now I catalog the questionable items that I eat or drink (those containing traces of gluten or dairy) in my mood journal in case I have a reaction.

After reading bestselling books “Grain Brain” by David Perlmutter, M.D. and “The Ultramind Solution” by Mark Hyman, M.D., I realized that certain foods can trigger inflammation in our bodies just like toxins from the environment. And while some people like my husband break out in hives, other folks like me get sad and anxious and start making plans to exit this earth. According to Hyman, these delayed reactions to food or hidden allergens lead to “brain allergies,” allergic reactions in the body that cause inflammation in the brain.

6. Caffeine Withdrawal

I’ll always remember my sister’s advice last summer when I showed up to her Michigan farm shaking, crying, and unable to focus on a conversation. I was in the midst of a severe depressive episode. One morning was especially bad. I tried to bring my coffee cup to my lips, but my hands were quivering so much even that was difficult.

“The first thing I’d do is stop drinking that,” my sister said, matter-of-factly, pointing to my coffee. “Even one cup is enough to give me a panic attack,” she said. Since she was my twin, with biogenetic similarities, I paid attention.

Then I read “Caffeine Blues” by Stephen Cherniske, M.S., who has certainly done his homework on the matter and offers a compelling case for quitting “America’s number one drug” for good. It’s basic physics, really. What goes up must come down. So that high you get after a shot of espresso isn’t without its consequences. You just don’t associate the anxiety and depression you feel three hours later because you’re on to other things. However, your body going through withdrawal, and for those of us like my sister and me who are chemically sensitive to all amphetamine-like substances that raise dopamine levels, that withdrawal translates to tears, shaking, panic attacks, and other forms of suffering.

Jan. 20, 2012 — Even mild dehydration may affect our moods and ability to concentrate.

In a new study of 25 healthy women, mild dehydration dampened moods, increased fatigue, and led to headaches.

The women in the study were aged 23, on average. They were neither athletes nor couch potatoes. Women participated in three experiments separated by 28 days. In two of these, dehydration was induced via walking on a treadmill with or without a diuretic pill. These pills encourage urination, and can lead to dehydration.

The women were given a battery of tests measuring their concentration, memory, and mood when they were dehydrated and when they were not.

Overall, women’s mental ability was not affected by mild dehydration. But they did have an increase in perception of task difficulty and lower concentration.

But “women were more fatigued and this was true during mild exercise and when sitting at a computer,” says researcher Lawrence E. Armstrong, PhD. He is a professor of environmental and exercise physiology at the University of Connecticut’s Human Performance Laboratory in Storrs, Conn.

The findings appear in The Journal of Nutrition.

Armstrong and colleagues previously looked at the effects of mild dehydration in men. Although men did experience some subtle mental difficulties when dehydrated, the risks were pretty similar between the sexes.

The message is clear, he says: “We should focus on hydration and continue to drink during meals and when we are not at meals.”

Water and Depression, Stress and Anxiety

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Stress, depression and anxiety are three very different conditions. However, many people experience a combination of these three. Sometimes the stress can lead to the other two, for example. There are many things that can be done to heal these emotionally tolling conditions, including removing stressors from our lives, taking medications, resting, exercising, meditation, yoga and more. However, did you know that water can also help?

The three of these disorders are mood disorders, perhaps stemming from the brain. Studies link depression to dehydration because 85% of brain tissue is water. Dehydration causes energy generation in the brain to decrease. So, lack of water can be the culprit in any of these disorders really. However, like in many other medical areas, contaminated water can also cause health problems. It is a known that lead in water can cause damage to nervous systems, with depression being one of the most common results of lead-filled water. A reverse osmosis filter is one the best ways to ensure that you are drinking safe water. Now, let’s move on to more ways water can help us.

There are several types of anxiety disorders, the most common being general anxiety disorder (GAD). Beverages with caffeine can increase anxiety. Replacing soda, tea and coffee with water is a good place to start. It is important to limit the consumption of caffeine, sugary drinks and alcohol. All of these liquids cause dehydration because it takes the body even more water to remove it from your body. Depending on the drink it can take your body up to 3 times the amount of water to process that drink. For example if you drink 12oz of beer it will take your body 36 ounces of water to flush out that beer. If you don’t give your body the amount of water it needs it will take it from your bones, muscles, and most importantly your brain.

Some studies show that water is a great “anxiety quencher”. When the body is dehydrated, in can actually induce anxiety and nervousness. When we are dehydrated our cells feel it at the molecular level and communicate this to the subconscious as an underline subtle anxiety or threat to survival. The key to rebalance this deficit of fluids is to drink eight glasses of fresh water a day. Water alone may not cure GAD and other related disorders, but it can sure calm those nerves! As a side note, there are many herbal supplements, such as PureCalm, that can be added to water to calm nerves as well.

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Depression, stress, and anxiety are some of the major issues faced by people in India, irrespective of their age group. Though these are very different conditions, many people may face a combination of all of the three conditions. According to a report by WHO, more than 5 crore people in India suffer from depression, which is alarmingly high. While acute depression needs medical help, making some changes in lifestyle can help in avoiding the situation. Many people are unaware of the fact that there is a direct relationship between depression and dehydration. In fact, dehydration is one of the symptoms of depression. In this blog, we discuss in detail the relation between depression and dehydration. Read on.

Signs and Symptoms of Depression

Some of the common symptoms of depression are:

  • Anxiety
  • Irritability
  • Lack of energy
  • Untimely tiredness
  • Craving for sugar
  • Feeling down

Also Read: 5 Common Health Problems that you may face because of Dehydration

Dehydration and Depression- Where is the Link?

A common question that people have is how can dehydration lead to depression, stress and anxiety or a combination of all three? Here is some important fact that you need to know. 85% of your brain tissues are made up of water. As a result, when don’t drink enough pure water with the essential minerals, you will fall sick. Dehydration also reduces serotonin production, which is one of the main reasons for depression. When calculating the amount of water that you drink, avoid including tea, coffee, sodas or juices that you drink. Surprisingly, these drinks lead to acute dehydration. Even 2% dehydration leads to degraded mood, lower concentration, or headaches.

Effect of Dehydration on Serotonin Level

One of the main reasons for depression is decreased serotonin levels, which is an important neurotransmitter. Serotonin also plays an important role in determining your mood. Tryptophan, which is an amino acid converts to serotonin. Your body needs to have sufficient water to transmit tryptophan across your brain. When you are dehydrated, the amount of tryptophan in your brain is limited, which ultimately affects the serotonin level. Apart from tryptophan, dehydration also has a negative impact on the level of amino acids in your body. Depletion of essential amino acid levels makes you feel dejected, anxious, irritable and inadequate.

Effect of Dehydration on Stress Levels

Stress, which can be triggered by dehydration, is another biggest factor that leads to depression. If you are dehydrated, your cortisol levels drastically increase. When you are stressed, the adrenal glands produce more cortisol. Under too much stress, the adrenal glands become exhausted. Adrenal glands also produce aldosterone, which plays an important role in regulating the fluids in your body and electrolyte levels. When your adrenal glands become exhausted due to stress, aldosterone production decreases leading to dehydration. Drinking enough water can minimize the chances of stress.

Effect of Dehydration on your Brain Energy

Dehydration can also reduce the production of energy in your brain. When you are dehydrated, the energy generation in the brain decreases. Many functions of your body depend on the energy produced by your brain. The absence of energy causes the functions that depend on the energy produced by the brain to become inefficient.

Dehydration and Panic Attacks

Anxiety caused by dehydration also results in panic attacks. Dehydration is one of the main triggers of a panic attack. When you are dehydrated, if you suffer from panic attacks, you easily start panicking. In addition, you may also experience the following symptoms of a panic attack:

  • Increased heart rate
  • Headaches
  • Feeling lightheaded
  • Muscle weakness and fatigue

Staying hydrated may not stop panic attacks; however, these may become less frequent or diminish with time.

Signs of Dehydration

If you notice any of the symptoms, you are dehydrated:

  • Increased hunger: The same part of your brain signals about hunger and thirst. If you feel hungry even after eating enough, it’s a sign of dehydration.
  • Dryness: Itchy, dry skin, dry mouth, chapped lips are all signs of dehydration
  • Headache: Lack of water leads to a shortage of oxygen supply to the brain, thereby leading to headaches.
  • Fatigue and Muscle Cramps: Muscle weakness, spasms, cramping are also signs of dehydration

How Much Water is Sufficient?

The ideal amount of water that you need to drink depends on your weight, age, gender, stress level, exercise regime, and other health conditions. You need to increase your water intake in the following circumstances:

  • Prolonged exercise
  • Extreme temperature
  • Illness such as fever, diarrhea, or vomiting
  • Dieting
  • Pregnancy
  • Chronic health conditions

You can monitor your hydration level by monitoring the color of urine. However, ensure that you avoid contaminated water which can do more harm than good. The presence of lead in water may damage your nervous system and prolong exposure can lead to depression. Installing an RO water purifier is one of the best ways to ensure that you get 100% safe and lead-free drinking water. In addition to RO purifier, you can also check the other range of purifiers available with KENT. To find out more about the different range of KENT water purifiers, click here.

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Dehydration Influences Mood, Cognition

While most understand that dehydration can have medical complications, a new study shows that even mild dehydration can influence mood, energy levels and the ability to think clearly.

Regrettably, we often use thirst as an indicator for when we need to drink — a response that experts say is too late to avoid many of the detrimental effects of dehydration.

In two recent studies, researchers at the University of Connecticut’s Human Performance Laboratory discovered the mental, mood and cognitive downside of even mild dehydration.

Investigators determined that it didn’t matter if a person had just walked for 40 minutes on a treadmill or was sitting at rest – the adverse effects from mild dehydration were the same.

Mild dehydration is defined as an approximately 1.5 percent loss in normal water volume in the body.

The take home message is that individuals need to stay hydrated at all times, not just during exercise, extreme heat or exertion.

“Our thirst sensation doesn’t really appear until we are 1 or 2 percent dehydrated. By then dehydration is already setting in and starting to impact how our mind and body perform,” says Lawrence E. Armstrong, one of the studies’ lead scientists and an international expert on hydration.

The importance for everyone to stay hydrated is a message that needs to be promoted.

“Dehydration affects all people, and staying properly hydrated is just as important for those who work all day at a computer as it is for marathon runners, who can lose up to 8 percent of their body weight as water when they compete.”

In the study, separate groups of young women and men were tested. Twenty-five women with an average age of 23 took part in one study. The men’s group consisted of 26 men with an average age of 20.

All of the participants were healthy, active individuals, who were neither high-performance athletes nor sedentary — typically exercising for 30 to 60 minutes per day.

Each participant took part in three evaluations that were separated by 28 days. All of the participants walked on a treadmill to induce dehydration, and all of the subjects were hydrated the evening before the evaluations commenced.

As part of the evaluation, the subjects were put through a battery of cognitive tests that measured vigilance, concentration, reaction time, learning, memory, and reasoning. The results were compared against a separate series of tests when the individuals were not dehydrated.

The young women experienced mild dehydration which caused headaches, fatigue, and difficulty concentrating. They also perceived tasks as more difficult when slightly dehydrated, although there was no substantive reduction in their cognitive abilities.

The research findings are published in The Journal of Nutrition.

In the tests involving the young men, mild dehydration caused some difficulty with mental tasks, particularly in the areas of vigilance and working memory, according to the results of the second UConn study.

While the young men also experienced fatigue, tension, and anxiety when mildly dehydrated, adverse changes in mood and symptoms were “substantially greater in females than in males, both at rest and during exercise,” according to the study. The men’s study was published in the British Journal of Nutrition.

“Even mild dehydration that can occur during the course of our ordinary daily activities can degrade how we are feeling – especially for women, who appear to be more susceptible to the adverse effects of low levels of dehydration than men,” says Harris Lieberman, one of the studies’ co-authors.

“In both sexes these adverse mood changes may limit the motivation required to engage in even moderate aerobic exercise. Mild dehydration may also interfere with other daily activities, even when there is no physical demand component present.”

Investigators are uncertain why women and men are so adversely affected by mild dehydration. One possibility is that neurons in the brain detect dehydration. These neurons may then signal parts of the brain regulating mood.

This process could be part of an ancient warning system protecting humans from more dire consequences, and alerting them to the need for water to survive.

In order to stay properly hydrated, experts like Armstrong recommend that individuals drink eight, 8-ounce glasses of water a day, which is approximately equivalent to about 2 liters of water.

People can check their hydration status by monitoring the color of their urine. Urine should be a very pale yellow in individuals who are properly hydrated.

Urine that is dark yellow or tan in color indicates greater dehydration. Proper hydration is particularly important for high-risk groups, such as the elderly, people with diabetes, and children.

Source: University of Connecticut

Water bottles photo by .

Dehydration Influences Mood, CognitionStudies by UConn’s Human Performance Laboratory affirm the importance of staying properly hydrated at all times.

Most people only think about drinking water when they are thirsty; but by then it may already be too late.

Even mild dehydration can alter a person’s mood, energy level, and ability to think clearly, according to two studies recently conducted at the University of Connecticut’s Human Performance Laboratory.

The tests showed that it didn’t matter if a person had just walked for 40 minutes on a treadmill or was sitting at rest – the adverse effects from mild dehydration were the same. Mild dehydration is defined as an approximately 1.5 percent loss in normal water volume in the body.

The test results affirm the importance of staying properly hydrated at all times and not just during exercise, extreme heat, or exertion, says Lawrence E. Armstrong, one of the studies’ lead scientists and a professor of physiology in UConn’s Department of Kinesiology in the Neag School of Education.

“Our thirst sensation doesn’t really appear until we are 1 or 2 percent dehydrated. By then dehydration is already setting in and starting to impact how our mind and body perform,” says Armstrong, an international expert on hydration who has conducted research in the field for more than 20 years. “Dehydration affects all people, and staying properly hydrated is just as important for those who work all day at a computer as it is for marathon runners, who can lose up to 8 percent of their body weight as water when they compete.”

Separate groups of young women and men were tested. Twenty-five women took part in one study. Their average age was 23. The men’s group consisted of 26 men with an average age of 20. All of the participants were healthy, active individuals, who were neither high-performance athletes nor sedentary – typically exercising for 30 to 60 minutes per day.

Each participant took part in three evaluations that were separated by 28 days. All of the participants walked on a treadmill to induce dehydration, and all of the subjects were hydrated the evening before the evaluations commenced. As part of the evaluation, the subjects were put through a battery of cognitive tests that measured vigilance, concentration, reaction time, learning, memory, and reasoning. The results were compared against a separate series of tests when the individuals were not dehydrated.

In the test involving the young women, mild dehydration caused headaches, fatigue, and difficulty concentrating, according to one of the studies, which appears in the February issue of The Journal of Nutrition. The female subjects also perceived tasks as more difficult when slightly dehydrated, although there was no substantive reduction in their cognitive abilities.

In the test involving the young men, mild dehydration caused some difficulty with mental tasks, particularly in the areas of vigilance and working memory, according to the results of the second UConn study. While the young men also experienced fatigue, tension, and anxiety when mildly dehydrated, adverse changes in mood and symptoms were “substantially greater in females than in males, both at rest and during exercise,” according to the study. The men’s study was published in the British Journal of Nutrition in November 2011.

“Even mild dehydration that can occur during the course of our ordinary daily activities can degrade how we are feeling – especially for women, who appear to be more susceptible to the adverse effects of low levels of dehydration than men,” says Harris Lieberman, one of the studies’ co-authors and a research psychologist with the Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine in Natick, Mass. “In both sexes these adverse mood changes may limit the motivation required to engage in even moderate aerobic exercise. Mild dehydration may also interfere with other daily activities, even when there is no physical demand component present.”

Why women and men are so adversely affected by mild dehydration is unclear, and more research is necessary. But other research has shown that neurons in the brain detect dehydration and may signal other parts of the brain regulating mood when dehydration occurs. This process could be part of an ancient warning system protecting humans from more dire consequences, and alerting them to the need for water to survive.

In order to stay properly hydrated, experts like Armstrong recommend that individuals drink eight, 8-ounce glasses of water a day, which is approximately equivalent to about 2 liters of water. People can check their hydration status by monitoring the color of their urine. Urine should be a very pale yellow in individuals who are properly hydrated. Urine that is dark yellow or tan in color indicates greater dehydration. Proper hydration is particularly important for high-risk groups, such as the elderly, people with diabetes, and children.

The dehydration studies were supported by Danone Research of France and were conducted in partnership with the U.S. Army Research Institute of Environmental Medicine, University of Arkansas, and Texas Health Presbyterian Hospital’s Institute for Exercise and Environmental Medicine in Dallas, Texas. UConn professor Douglas Casa, adjunct assistant professor Elaine Lee, and members of the graduate student team at UConn’s Korey Stringer Institute for the prevention of sudden death in sport helped gather data for the two studies.

Link between hunger and mood explained

University of Guelph researchers have revealed that the sudden drop in glucose we experience when we are hungry can impact our mood.

“We found evidence that a change in glucose level can have a lasting effect on mood,” said Prof. Francesco Leri, Department of Psychology. “I was skeptical when people would tell me that they get grouchy if they don’t eat, but now I believe it. Hypoglycemia is a strong physiological and psychological stressor.”

Published in the journal Psychopharmacology, the study examined the impact of a sudden glucose drop on emotional behaviour by inducing hypoglycemia in rats.

“When people think about negative mood states and stress, they think about the psychological factors, not necessarily the metabolic factors,” said PhD student Thomas Horman, who led the study. “But we found poor eating behaviour can have an impact.”

The rats were injected with a glucose metabolism blocker causing them to experience hypoglycemia, and were then placed in a specific chamber. On a separate occasion, they were given an injection of water and placed in a different chamber. When given the choice of which chamber to enter, they actively avoided the chamber where they experienced hypoglycemia.

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“This type of avoidance behaviour is an expression of stress and anxiety,” said Leri. “The animals are avoiding that chamber because they had a stressful experience there. They don’t want to experience it again.”

The researchers tested blood levels of the rats after experiencing hypoglycemia and found more corticosterone, an indicator of physiological stress.

The rats also appeared more sluggish when given the glucose metabolism blocker.

“You might argue that this is because they need glucose to make their muscles work,” said Leri. “But when we gave them a commonly used antidepressant medication, the sluggish behaviour was not observed. The animals moved around normally. This is interesting because their muscles still weren’t getting the glucose, yet their behaviour changed.”

This finding supports the idea that the animals experienced stress and depressed mood when they were hypoglycemic, he said.

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For people who experience anxiety or depression, the study results have implications for treatment, said Horman.

“The factors that lead someone to develop depression and anxiety can be different from one person to the next. Knowing that nutrition is a factor, we can include eating habits into possible treatment.”

These findings also provide insight into the connection between depression and diseases such as obesity, diabetes, bulimia and anorexia, Horman said.

Having established that hypoglycemia contributes to negative mood states, the researchers plan to determine whether chronic, long-term hypoglycemia is a risk factor for developing depression-like behaviours.

While missing one meal may make you “hangry,” Horman said, these findings suggest your mood could be impacted if meal-skipping becomes a habit.

“Poor mood and poor eating can become a vicious cycle in that if a person isn’t eating properly, they can experience a drop in mood, and this drop in mood can make them not want to eat. If someone is constantly missing meals and constantly experiencing this stressor, the response could affect their emotional state on a more constant level.”

Mood effects of ‘hunger hormone’

“High levels of the ‘hunger hormone’ ghrelin have an antidepressant effect”, BBC News reported today. It said that a study in mice found that those whose food intake was restricted for 10 days had four times the normal levels of ghrelin, and showed fewer signs of anxiety and depression in behavioural tests.

According to the BBC, the researchers said there have been suggestions that blocking the body’s response to the hormone could be a possible weight-loss treatment. This new study however, found that it may also produce “unintended effects on mood”.

The researchers are quoted in the article as saying that although signs of depression and anxiety decrease as ghrelin levels increase, “an unfortunate side effect…is increased food intake and body weight”. The researchers now want to look at the antidepressant effect of ghrelin in conditions such as anorexia.

This study has shown a link between ghrelin and anxiety and depression-like behaviour in mice. However, much more research will be needed to determine whether this hormone plays a role in anxiety and depression in humans.

Where did the story come from?

Dr Michael Lutter and colleagues from the University of Texas Southwestern Medical Centre carried out the research. The study was funded by the US National Institutes of Health, the Foundation for Prader-Willi Research, NARSAD Young Investigator Award, and a University of Texas Southwestern Disease-Oriented Clinical Scholar award. The study was published in the peer-reviewed scientific journal Nature Neuroscience.

What kind of scientific study was this?

Chronic stress can lead to changes in eating patterns and metabolism, and eating and metabolism may in turn affect mood, but this has not been thoroughly studied. In this laboratory study in mice, the researchers looked at whether mood was affected by the hormone ghrelin. This hormone is released by the digestive system and tells the brain that the animal needs to eat.

In the first part of their experiment, the researchers split the mice into two groups: one group could eat as much as they wanted, while the other group had their food intake cut by 60% for 10 days so that their ghrelin levels would increase. The mice then took part in two standard tests to measure their depression- and anxiety-like behaviours: a maze test and a swimming test. In the maze test, the researchers looked at how long the mice spent exploring the open and closed corridors of the maze, how often they entered the different types of corridor, and how fast they went. Mice showing anxiety-like behaviour prefer closed corridors to open corridors. In the swim test, mice were placed in water and the researchers measured how long they continued to swim. Mice with depression-like behaviour will not swim as long.

The researchers then repeated this experiment in mice who had been genetically modified so that their ghrelin signalling was blocked. These mice had a missing protein, which is found on the surface of brain cells and binds to ghrelin to allow it to transmit its signal. In this second set of experiments, the researchers took two groups of mice and injected one group with ghrelin, and the other with salt water, then compared their performance on maze and swim tests.

In the third set of experiments, the researchers looked at ghrelin levels in mice that had been exposed to chronic stress by being caged with more aggressive mice. Mice which have been exposed to these conditions show depression-like behaviours, including avoidance of other mice. The researchers also exposed mice with blocked ghrelin signalling to similar conditions and examined the effects.

What were the results of the study?

The researchers found that mice with restricted food intake had ghrelin levels four times higher than mice that could eat what they wanted (normal mice). The food-restricted mice showed more anxiety- and depression-like behaviours than normal mice on the maze and swim tests. These effects on mood were not seen if food was restricted in mice whose ghrelin signalling had been blocked.

They also found that injecting mice with ghrelin reduced their anxiety- and depression-like behaviours during maze and swim tests. Mice which had been exposed to chronic stress had elevated ghrelin levels and ate more food. Chronic stress in mice whose ghrelin signalling had been blocked led to worse depression-like behaviours (avoidance of other mice), and their food intake was not altered.

What interpretations did the researchers draw from these results?

The researchers concluded that they had identified a previously unknown role for ghrelin in regulating mood. Ghrelin levels can be increased by chronic stress and can reduce anxiety and depression-like behaviours. These findings may be relevant to the psychological effects of conditions such as anorexia, where ghrelin levels are known to be altered.

What does the NHS Knowledge Service make of this study?

This study has shown a link between ghrelin, a hormone that promotes hunger, and anxiety and depression-like behaviours in mice. However, how ghrelin might cause a reduction in these behaviours in mice is not clear, and other factors will also play a role.

Much more research will be needed to look into whether this hormone plays a role in anxiety and depression in humans.

Sir Muir Gray adds…

Never mind the mice; to prevent weight gain walk an extra 3000 steps (30 mins) a day; if you want to accelerate weight loss, walk an extra 60 mins a day.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

BBC News, 16 June 2008

Links to the science

Lutter M, Ichiro Sakata I, Osborne-Lawrence S, et al.

The orexigenic hormone ghrelin defends against depressive symptoms of chronic stress.

Nature Neurosci 2008; Jun 15

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