By Talia Beechick
Although calling someone “anorexic” has become a middle-school attack levelled at anyone deemed too skinny, it’s important not to forget that the word describes a deadly serious disorder. Eating disorders carry the highest mortality rate of all mental illnesses, and anorexia is the third most common chronic illness among adolescents; 95% of its victims are between the ages of 12 and 25. Despite this threat, there are still gaps in our knowledge of the disease, but recent studies are trying to fix this.
This much is known: anorexia is characterized by the inability to maintain a healthy, appropriate weight, victims often experience body image distortion, an altered appetite, a strong fear of gaining weight and a lack of menstruation among female sufferers. This intense fear of weight gain can literally control a person’s mind; thoughts become constantly fixated on calories, fat intake, exercise to counteract food, ways to skip meals and that little number popping up on the scale.
This fear, combined with the inability to accurately perceive one’s own reflection due to a distorted body image has confused scientists ever since the eating disorder was recognized in the late nineteenth century. Since then, controversy has surrounded anorexia and its causes. Some scientists presume it occurs due to high levels of anxiety and obsessive behaviors, others say social influence is the major factor.
One recent study leverages the burgeoning field of brain imaging and newly recovered anorexic patients in an attempt to prove a connection between the disturbance of brain circuits and abnormalities within appetite and mood.
Researchers at University of California, San Diego (UCSD), led by Eating Disorders Program director Walter Kaye, began using brain imaging to highlight neurocircuit dysfunction within anorexic patients to help explain the curious behaviors and symptoms of this disorder. Beginning in 2009, the study is ongoing with new information being released at sporadic intervals as the researchers continue linking the former behaviors and desires of the patients to their brain structure and function.
New Research Could Help Explain How People Become Anorexic and How to Treat Anorexia
One such tie has been discovered between the dysfunction of ventral and dorsal neural circuits in patients and their inability to view food as a positive reward or presence in their lives. Discovered through positron emission topography (PET) brain imaging of anorexic and newly-recovered anorexic patients, both the ventral (limbic) neurocircuit and the dorsal (cognitive) neurocircuit contain several structures which contribute to appetite and the regulation of food consumption. The dysfunction of these circuits plays a role in several disorders, such as depression, anxiety, and obsessive-compulsive disorders.
Researchers also found altered levels of neurotransmitters such as serotonin and dopamine. Serotonin regulates mood and appetite and is typically associated with inhibitory behavior, whereas dopamine is involved with behavior, motivation, reward and mood. Research has indicated that these modified levels are largely significant in anorexic-type behaviors. Alterations within serotonin levels, for example, may lead to vulnerability for restricted eating and a bias towards consequences, whereas dopamine dysfunction may impact decision making, an altered sense of rewards and decreased food ingestion. When paired with the disturbances of the ventral and dorsal circuits, these altered neurotransmitter levels may clarify why patients are constantly worried about the long-term consequences of eating and also may help shed light on their immunity to the immediate gratification and pleasure of food.
Furthermore, an imbalance between enhanced serotonin receptor 1A and diminished 2A receptor binding potential has been discovered among patients with anorexia. Eating carbohydrates stimulates these receptors, which may increase extracellular serotonin levels and actually cause a mood shift towards depression, irritability, and anxiety. This explains why starvation, which may lower these extracellular serotonin levels, provides temporary relief from this mood.
These imaging studies also have found disturbances in other regions of the brain, such as the insular brain cortex, which plays a significant role in your body’s awareness of itself. This awareness involves many different bodily sensations including hunger and satiety. Therefore, disturbances within the insular brain cortex combined with altered functions of other brain regions may literally render the anorexic patient unable to recognize the sensation of hunger: their perception of the feeling is shut down completely.
Research suggests other factors are significant when attempting to explain anorexia, one being childhood personality and temperament traits. These traits include perfectionism, obsession with detail/inability to focus on the big picture, behavioral inhibition, harm avoidance, and anxiety. Because these characteristics are so engrained within the patients, they tend to remain and continue within patients even after recovery, suggesting a deeper, neurobiological factor of the disorder.
This is also supported by the stereotypical, almost systematic way the disease develops within an individual; usually occurring within adolescent females, puberty, brain development and anxiety/social stresses tend to provoke anorexic tendencies. The starving and malnutrition that follow eventually affect the entire body, including the brain, which causes neurochemical imbalances. These irregularities tend to exaggerate the previous traits (i.e. anxiety and perfectionism) and accelerate the disorder into a self-sustaining spiral. One such irregularity is a reduced brain volume, though Kaye affirms these brain alterations are normalized after the recovery process.
What are the implications of these discoveries? Ultimately, the UCSD Eating Disorders department aims to perform further scientific research in this field to provide a better understanding of this disorder and more effective treatment for sufferers of anorexia. Because researchers are beginning to prove the significant role brain processes have it is becoming known as a biologically-based brain disorder – a fact which has driven insurance companies to begin covering eating disorders in a similar manner to other physical maladies.
These studies also strive to find ways to prevent relapse within recovered patients, for only 30-40% of victims ever fully recover from their illness. Eating disorders have serious, detrimental impact on mental functioning, heart processes, skeletal growth, mouth health, the endocrine system, the stomach and intestines. Malnutrition affects nearly every part and function of the body, and is an extremely dangerous cycle to fall into.
It is fascinating to see an old, well-known problem get a second look from the ever-expanding field of neuroscience. The study of anorexia’s neurological roots is just a window into the promising technology, one which, going forward, will touch our lives in unexpected ways.
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