(Press-News.org) Perhaps the most puzzling symptom of anorexia nervosa – a disorder that tends to occur in young women – is the refusal to eat, resulting in extreme weight loss. While most people have a great deal of difficulty in dieting and losing weight, particularly if a diet extends over many months or years, individuals with anorexia nervosa can literally diet themselves to death. In fact, this disorder has a very high death rate from starvation. A new study, now online in the journal International Journal of Eating Disorders, sheds light on why these symptoms occur in anorexia nervosa.
Most people find eating to be a pleasant and rewarding experience. In contrast, people with anorexia nervosa often say that eating makes them more anxious, and food refusal makes them feel better. Research over the past decade has provided new insights into the brain mechanisms that are associated with the rewarding aspects of eating. One of these brain chemicals is dopamine, which is released when people or animals eat tasty foods.
A study led by Walter Kaye, MD, professor of psychiatry and director of the Eating Disorder Treatment and Research Program at the University of California, San Diego School of Medicine, used a brain imaging technology called positron emission tomography (PET), which permits visualization of dopamine function in the brain. In order to provoke dopamine levels in the brain, scientists administered a one-time dose of the drug amphetamine, which releases dopamine in the brain.
In healthy women without an eating disorder, amphetamine-induced release of dopamine was related to feelings of extreme pleasure in a part of the brain known as a "reward" center. However, in people who had anorexia nervosa, amphetamine made them feel anxious, and the part of the brain that was activated was, instead, a part of the brain that worries about consequences.
"This is the first study to demonstrate a biological reason why individuals with anorexia nervosa have a paradoxical response to food," said Kaye. "It's possible that when people with anorexia nervosa eat, the related release of the neurotransmitter dopamine makes them anxious, rather than experiencing a normal feeling of reward. It is understandable why it is so difficult to get people with anorexia nervosa to eat and gain weight, because food generates intensely uncomfortable feelings of anxiety."
Importantly, this study was of people who have recovered from anorexia nervosa for at least a year, suggesting that the feeling provoked may be due to pre-existing traits, rather than a response to being at an extremely low weight.
In terms of impact on treatment strategies, there are no currently proven treatments that reduce core symptoms in anorexia nervosa, such as eating-induced anxiety. According to the researchers, even though food is accompanied by severe anxiety, it is still critical to eat and gain weight in order to effectively treat this disorder.
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Contributors to the study include Ursula F. Bailer, MD, Medical University of Vienna and UCSD Department of Psychiatry; Vikas Duvvuri, MD, PhD, UCSD Department of Psychiatry; and Rajesh Narendran, MD, W. Gordon Frankle, MD, Michael L. Himes and Chester A. Mathis, PhD, University of Pittsburgh School of Medicine. These results have been published on line in the International Journal of Eating Disorders.
The study was supported in part by the National Institute of Mental Health and the Prince Foundation.
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Los Angeles, CA (May 18, 2011) When people have power, they act the part. Powerful people smile less, interrupt others, and speak in a louder voice. When people do not respect the basic rules of social behavior, they lead others to believe that they have power, according to a study in the current Social Psychological and Personality Science (published by SAGE).
People with power have a very different experience of the world than people without it. The powerful have fewer rules to follow, and they live in environments of money, knowledge and support. People without power ...
SEATTLE – Although chemotherapy is used to kill cancer cells, it can also have a strong toxic effect on normal cells such as bone marrow and blood cells, often limiting the ability to use and manage the chemotherapy treatment. Researchers at Fred Hutchinson Cancer Research Center reported at today's annual meeting of the American Society of Gene and Cell Therapy in Seattle that one possible approach to reduce this toxic effect on bone marrow cells is to modify the cells with a gene that makes them resistant to chemotherapy.
Hans-Peter Kiem, M.D., a member of the Hutchinson ...
New research provides evidence for significant differences between new and old red blood cells used for transfusions and could provide a cheap, rapid and effective way to monitor the quality of blood supplies.
Even with preservatives, blood stored in banks continues to age, resulting in biomaterials leaking from the red blood cells and subsequent changes to cell properties and function. There have been concerns raised worldwide about using older stored blood because of questions about various changes believed to affect the quality of the red blood cells. Currently, ...
Researchers from the King Juan Carlos University (URJC) have carried out a research study published in Biological Conservation, which looked at whether spiders were more tolerant of human impact than other animals. The answer was no: arachnids suffer the consequences of changes to their landscape just like any other animal.
"The abundance and number of spider species is negatively affected by the impact of many human land uses, such as habitat fragmentation, fire and pesticides", Samuel Prieto-Benítez and Marcos Méndez, researchers at the URJC Biodiversity and Conservation ...
Together with the national science academies of the other G8 states, the German National Academy of Sciences Leopoldina has prepared two statements for the G8 states in the run-up to the G8 Summit of Heads of State and Government. The recommendations contained in these statements were now presented to the participating governments for the negotiations in Deauville, France on 26 and 27 May. In a statement on the topic of "Education for a Science-Based Global Development", the academies urge governments to target investment to establish an infrastructure for a globalization ...
The University of Southampton is playing a key role in a major public/private partnership to evaluate the use of biomass to create a cost effective and sustainable UK energy system for 2050.
Domestic biomass (a renewable energy source from living, or recently living organisms, such as plants, rubbish and wood), sustainably grown in the UK, could provide up to 10 per cent (1) of the UK's energy needs by 2050 and significantly contribute to the reduction of greenhouse gas (GHG) emissions.
Three new bio energy projects launched by the Energy Technologies Institute (ETI), ...
This week the scientific journal Ecology Letters has published a synthesis of the ecological impacts of invasive plants worldwide. This global analysis has been based on more than one thousand studies that in total describe the impacts of 135 invasive plant species. The lead author, Dr. Montserrat Vilà, a professor at the Spanish Higher Research Council (CSIC) adds: "This assessment would have been impossible to achieve ten years ago, because the evidence was anecdotal, it has only been in the last decade that well designed field studies have been conducted".
Twenty-four ...
Many drugs sold as 'legal highs' on the internet do not contain the ingredients they claim. Some instead contain controlled substances and are illegal to sell over the internet. These are findings of Dr. Mark Baron, who bought a range of tablets from different websites to see what each contained. The study is published today in the journal Drug Testing and Analysis.
"It is clear that consumers are buying products that they think contain specific substances, but that in reality the labels are unreliable indicators of the actual contents," says Dr. Baron, who works in the ...
VIDEO:
Wizen and Gasith's current study shows that adult Epomis beetles can prey upon live amphibians, in addition to their regular diet.
Click here for more information.
New findings of researchers from Tel-Aviv University show that predator-prey interactions between ground beetles of the genus Epomis and amphibians are much more complex than expected. The study was published in the open access journal Zoo Keys.
"Amphibians are typical insect predators and their diet ...
Rima Taher, an expert in the design of low-rise buildings for extreme winds and hurricanes, will speak next week at the Annual Conference of Construction Specifications Canada (Devis de Construction Canada) in Montreal. Taher, a university lecturer in NJIT's College of Architecture and Design, is a civil and structural engineer, http://www.njit.edu/news/experts/taher.php. Construction Specifications Canada (http://csc-dcc.ca) is a national, non-profit association with chapters across Canada. Its mission is to deliver and develop quality educational programs, publications ...
