Wednesday, October 27, 2010

Guest post: Shan Guisinger

In my book Brave Girl Eating, I wrote about one theory of the origins of anorexia: psychologist Shan Guisinger's adapted-to-flee-famine theory.

I'm very pleased to have Dr. Guisinger writing about her theory on the blog today. I think it's a fascinating concept that deserves further thought. Please write in with comments and questions.


Dear Harriet,

I’m happy that you described the adapted-to-flee-famine explanation for anorexia in Brave Girl Eating. I have found that it helps patients understand and fight their urges to restrict food and compulsively exercise.

The adapted-to-flee-famine hypothesis (2003) states that the distinctive symptoms of ignoring hunger, hyperactivity and denial of starvation were evolutionary adaptations that once helped starving hunter-gatherers make a last ditch effort to find better foraging grounds. This theory is supported by data from genetics, molecular biology and neuroimaging, yet eating disorders experts turn away from evolutionary explanations saying “we can never know for sure.” In fact, we regularly use circumstantial evidence and evidence based on probabilities to come to conclusions in science, the law, and in our lives.

For example, the criminal justice system has careful rules for evaluating circumstantial evidence because criminals rarely come forward to confess their crimes. Suppose someone were murdering teen-aged girls in your town. You would expect the police to arrest a man who had blood from the victims in his car, and you would expect a jury to convict him if the police found the murder weapon with his fingerprints, and if he had no alibi for where he was when the murders took place. How would you feel if the police let him go asserting that, without a confession, “we can never know for sure?” We would also be shocked if the judge let him go because he didn’t accept evidence based on probabilities, such as the DNA and fingerprint data.

This issue is not simply academic jousting. According to NIMH, the mortality rate for anorexia of 5.6% per decade is twelve times higher than the annual death rate due to all causes of death among young women between the ages of 15 and 25. And treatments based on the conventional assumptions have a dismal success rate. In fact McIntosh and colleagues found that patients in what was supposed to be the control group, given only nutritional counseling and emotional support, did better than those given cognitive-behavioral or interpersonal therapy which assume that anorexia is caused by psychological issues.

What is the evidence for the adapted-to-flee-famine hypothesis?

First, anorexia is now accepted as genetic. Although rare in the general population, if one identical twin has it, there is a 50% chance the other will develop it. Studies comparing identical and fraternal twins found that the increased risk is due to genetics and not to family environment. Moreover, the lack of long-term success of weight-loss programs demonstrates that without anorexia genes it is very difficult to maintain weight at 15% below normal. What anorexics do is physiologically and psychologically remarkable.

Second, denial of starvation and body size overestimation are demonstratively the result of unconscious machinations at the neuronal level. Brain imaging shows that the brain alters the reality that an underweight anorexic individual consciously perceives. When an anorexic looks at herself, her brain actively inhibits perceptual processing of visual input. This makes sense if the brain were trying to fool a starving person into thinking that she has the physical resources to travel.

Third, neuroendocrinologists have described the complex physiological changes that enable starving people with anorexia to feel like running for miles and refuse food offered. When leptin, a hormone that tracks fat stores, falls below a critical level, it activates neuronal circuits that reduce food intake and increase activity (Muller, 2010). Chen and colleagues (2004) have identified the gene, SIRT 1, that turns on hyperactivity in starving mice.

Natural selection is the only process that can produce such a network of specialized abilities, but ED researchers explain them as the result of a hodgepodge of biological breakdowns. Each favors a different dysfunction, for example, excess serotonin, impairments in set shifting, errors in reward pathways, and breakdowns in sensory integration.

The idea that biomedical dysfunctions are responsible for anorexia nervosa does not stand up to logic. For a person to develop the standard presentation of anorexia (difficulty eating, hyperactivity and body image distortion) at least three different accidents would have to happen together. The likelihood of this is very small. Moreover, the fact that the crucial biological changes of anorexia normalize with weight restoration indicates that they are a response to very low body weight, and not the cause.

In your book you eloquently describe how hard it is to recover from anorexia. It matters why people with anorexia feel they must restrict food and exercise. It matters in order for treaters to understand and help their patients; it matters to the person with anorexia to make sense of her experience of difficulty eating, drive to move, and body image. Treatment is often ineffective because, still today, most patients, therapists and doctors believe that anorexia nervosa is caused by the patient’s willful refusal to eat due to a need for control or to trying to be model thin. Their false belief is the result of the mind’s automatic attempt to make sense of anorexia’s puzzling feelings and behaviors.

Realizing that their bodies are trying to migrate helps people with anorexia overcome their anorexic urges; and, it helps their loved ones and their therapists to understand their struggle and perhaps support them in recovering their health.


Shan Guisinger, PhD


Bill said...

I have two friendly questions about this theory.

1. The biological theory may require events with low probability to occur, but isn't anorexia itself observed with low probability?

2. On this new theory, what is the cause of anorexia in a given person? How can one make sense of the claim that one's own body is trying to migrate?

Thank you.

Shan Guisinger said...

Dear Bill,

Thanks for your questions. The chance of 3 dysfunctions occurring together would be the likelihood of the first times the likelihood of the second, times the likelihood of the third, an infinitesimally small number. Yet these complex abilities occur in every one who develops anorexia. This is a signature of natural selection.

On your second question--AN is caused by serious weight loss in a person with the genetic ability to develop anorexia.

Regarding your question about making sense of what the body is doing: cognitive neuroscientists have discovered that a lot of our behavior is actually the result of nonconscious processes, but we explain our behavior according to the psychological theories of the day. Thank you. Shan Guisinger

Bill Fabrey said...

Guisinger's theory and defense/explanation of it is brilliant, and helps illuminate at least some of what is going on, including my daughter's former symptoms. I suspect that in many patients, a mix of causes, including this one, is at work. For example, the worship of the model-thin figure due to the society we live in might act as a trigger, if not a cause, in susceptible individuals with certain genes.

The evidence for Guisinger's theory, as described, is amazingly similar to that for obesity--twin studies, lack of effect of family environment, and so forth--and the propensity to put on fat deposits easily as a survival characteristic left over from famines. Yet fat people, like anorexics, often get scolded for being to blame for their condition.

Anonymous said...

Thank you very much for your helpful reply.

Your point, if I am understanding you correctly, is that in the past, significant loss of weight meant famine and the body protected itself accordingly. Today, loss of weight in the West does not mean famine, but the body of those who experience AN is still programmed genetically to respond in the same way.

So now I wonder what brings about significant loss of weight, such that the AN biological process begins?

Thank you again for your previous response.

Colleen said...

On a superficial level, what about the anorexic who does NOT exhibit hyperactivity or body image distortions, but only finds it impossible to eat (like my daughter)? Or the exercise purger who works out too much for her intake but does not find eating itself problematic? Or people who suffer from body image distortions (even dysmorphia) without concurrent anorexic or bulimic behaviors? Not all eating disorders present with all three characteristics.

On a more global level, I wonder why we have to find a WHY for anorexia. We don't look for evolutionary reasons for other diseases. What evolutionary purpose does Huntington's disease serve? Diabetes?

While I like the idea that AN serves a purpose and is not just pointless suffering, there are lots of diseases that are just that--pointless suffering. Do we want an 'explanation' for AN because its sufferers seems so rational in many ways? When you have a child doing very well at school but flat out refusing so much as a dry salad, it's hard not to look around for some explanation. What rational person would choose to starve to death?

The truth is there may be no explanation for it, no 'purpose' for anorexia. It's a brain disease that presents certain life-threatening behaviors and that might be all there is to it.

Trying to explain the irrational in terms of the rational doesn't make sense, and it has led to very poor therapy.

I think the problem is that AN has been considered a 'choice' for so long. It's a fairly recent discovery that these behaviors are the result of malfunctioning brain chemistry. Rational people would not choose this! And up until recently, we viewed AN as a 'choice' that the sufferer was making. In reality, AN is a rare physiological response to low nutrition and really doesn't have much to do with the culture itself (conceding that the culture may support the idea of fasting for religious purposes or dieting to achieve a certain look, which can trigger the disorder). But it's the fasting or the dieting itself that triggers AN in susceptible individuals, not the culture.

I agree with you that AN is biological in nature. I just don't think it needs a rationale.

I do like the happy ending you added to the story of the intrepid anorexic bringing food back to her hungry tribe: that the tribe would then 'lovingly feed her back to health.' As someone who lovingly fed her daughter back to health, armed with the knowledge that her protests, tantrums and rages were symptomatic of her anorexic brain disregulation, I'd guess the tribe members would be as bewildered as any other normal rational person and would think that this person just doesn't want to eat. The anorexic person would then continue starving to death...which has an evolutionary advantage of its own: the death of an individual during a time of scarce resources may ensure the survival of the tribe. More food for the rest of the tribe! The greater good and all that. Much more likely, sorry.

I think as long as we can focus on the biological and physiological presentations of AN, we will be able to move forward in treating them more effectively (and hopefully, someday, preventing them). Viewing AN as a biological illness rather than a personal choice or a cultural construct. I'm not sure that having a caveman story helps with treatment options. IMHO, the future of AN treatment lies in neurobiology, not so much in psychology.

Thanks for your thoughtful paper. I did enjoy it even if it sounds like I'm being very critical of it.

Anonymous said...

With advanced scientific techniques, it might be possible to test Dr. Guisinger's hypothesis. For example, scientists are now finding an evolutionary explanation for other diseases, including Type 1 diabetes. As we identify the genes associated with AN, we may well find that those genes, while contributing to the disease of AN, at other times in human history conferred a survival advantage. In the meantime, I think her hypothesis helps us to see AN as an illness, not a choice. Nobody is to blame. Food is medicine, not something to be feared.

Shan Guisinger said...

Dear Bill, Bill and Colleen,

Thank you for your comments. I hope you don’t mind if I respond to them together.

Bill Fabrey noted that “the propensity to put on fat deposits easily as a survival characteristic left over from famines. Yet fat people, like anorexics, often get scolded for being to blame for their condition.”

I hope that knowing that storing fat has an evolutionary rationale and is a genetic imperative for some people has decreased shaming. We realize that people can tell their body that there is not reason to store extra fat, but the hypothalamus, the part of the brain that sees to fat reserves is not plugged into the observing ego. The same is true of anorexia.

Himisterbill asked what brings about significant weight loss today. One risk periods for developing AN is 14 years. This is the age when a female is generally the leanest in her life. Girls who are naturally thin and active are at risk to develop anorexia after their prepubescent growth spurt and before they have put on pubertal weight. I have treated a number of 14-year-old girls whose anorexia began after these very lean “beanpoles,” lost additional weight from illness, an accident, or sports. Some of them assured me that they didn’t have anorexia nervosa because they were not dieting or trying to lose weight. But once anorexia started they had all the symptoms of difficulty eating, hyperactivity, and body image distortion that made recovery hard.

The other modal period is 18 years, and that is probably more often the result of dieting or overexercising. But anything that makes someone lose weight puts a genetically vulnerable person at risk. It is probably more common in the elderly than many health care givers realize.

Colleen asks about variations of eating disorders that do not have the stereotyped presentation?

I suspect most eating disorders are caused by the various defenses our bodies mount against starvation. For example, gorging is adaptive if you have been starved. I suspect that different aspects of these adaptations to famine are expressed, depending on what a persons genetic abilities are, and what they are doing to their bodies. To be healthy, I think we have to convince the hypothalamus that it is not longer in danger of being starved. That means getting enough good nutrition over a long period of time, never dieting, fasting or even going all day without eating, and not over-exercising. Easier said than done if you have an eating disorder, but the only thing that will work. As long as the hypothalamus thinks the body is in danger it will take over, and the person will find him or herself binging, restricting or compulsively exercising, even against their will.

Colleen asks On a more global level, I wonder why we have to find a WHY for anorexia. We don't look for evolutionary reasons for other diseases. What evolutionary purpose does Huntington's disease serve? Diabetes?

But if there were an explanation, wouldn’t we want to know it? We don’t want to make up a false story, but neither do we want to ignore a valid explanation.

The thing about anorexia is that the irrational behavior is not random; it is stereotyped. Quite different individuals come to sound alike, with the same phobias, same difficulty eating. That begs an explanation, especially for an evolutionary biologist like me. And as a clinical psychologist, I can attest that understanding why their body and mind are afraid of eating helps people to eat.

Thank you all for your comments,

Shan Guisinger

hannahmarie said...

Hi, I am a girl (16) who has been diagnosed to be "EDNOS" or Eating Disorder Not Otherwise Specified. I have characteristics of anorexia and also purging disorder (not exactly bulimia, I'm sure you know. I don't eat to purge. I do not purge after a moment of uncontrolled eating. My body simply cannot stand to feel full. Therefore, whenever it does, it throws whatever I tend to eat, a carrot or a cupcake, back up).

I hate my body. It's weight plummits and goes up a little and drops dramatically again. I've come to the point where I think of my body and my mind as two seperate beings. I don't call my body a part of "me" because if it was, you think I would charish it and love it as it were me.

After seeing a little into my world, how would you blame my behaviors on a theory that is nothing more than... Well.. A theory? Evolution has yet to be proven; therefore, i refuse to let myself and my actions be the result of it. My actions and thoughts are not those of the average person, and I'm aware of that. But I can't see anything in my mind that would say the results are from evolution. I know genes play a large role in eating disorders as well. My mom had just gotten out of eating disorder recovery a month before she was pregnant with me. But why don't any of my brothers or sisters have an eating disorder? They are all over the age of 28 and have never shown signs of difficulty eating or self hatred.

Mind you, I'm not just talking based on my own experiences with a disorder. I have done extensive class research papers on the subject of how eating disorders develope or why. I've read books on people who have had eating disorders and it hurts me to see others suffer, yes suffer, the way I do. I hate how specialists on eating disorders try to classify us all into one group because we each behave in different ways. We are all triggered by different things. We can't just say our behaviors are a result of something that could have or could not have happened in the past.

Another thing I can't stand about theropists and nutrition councelers on the subject of eating disorders is that they have no experience of an eating disorder other than observing those who have them. If they had at one time experienced an eating disorder previously in their lives, then they might have some insight on how to help others like us instead of basing their methods of recover off of how it happened. It is for this reason that I myself am going to college to be an eating disorder specialist. So I can not only have tools to help myself, but to be the person that can speak from experience, and help people in that way.

Bill Fabrey said...

This comment is from my friend Sarah, who had trouble posting, for some reason. She said:

"I am still confused why the threat of famine would cause someone to stop eating. I understand the overeating reaction, but the starving reaction makes no sense to me. If one was about to starve, why would one starve themselves?"

--Sarah, Fishkill, NY