Biology isn't destiny, but it still matters

Researchers have long known that brain diseases like mood disorders and anxiety run in families. In recent years, scientists have identified some of the specific gene variants that increase risk for these illnesses. All of this genetic research can almost make biology seem like destiny.

In fact, when I describe the biological and genetic basis for eating disorders, many people commonly say that it's depressing. That if an ED is biological, you can't get better (once an anorexic, always an anorexic). That any offspring will be doomed to repeat my eating disorder. Yet there is no 'anorexia gene,' no 'bulimia gene.' An eating disorder has been, and will always be, a complex interaction between nature and nurture, genes and environment, chemistry and culture.

Although it's a tad more complicated than this, genes essentially make proteins. Some proteins are so evolutionarily ancient and so important to your body that all humans will have identical copies of these proteins--one from their mother and one from their father. Some proteins have evolved more recently, or have greater flexibility in shape and form and function (the sequence of DNA ultimately determines the shape of a protein; the shape of a protein determines what job it does and how well it does that job). These particular proteins can tolerate small mutations, tiny changes to its shape, and so not all humans will carry the same copy. Several different versions of the gene, known as a polymorphism, exist among humans.

These polymorphisms aren't an on/off switch, an indication that you have the disease or you don't. Rather, they indicate that you are more likely to have an eating disorder, depression, anxiety, schizophrenia. This likelihood is also influenced by your life experiences (and the other way around), which can both increase or decrease your risk of becoming ill.

Researchers have found that genetics isn't destiny for those with anxiety disorders. In a study titled "What is an “Adverse” Environment? Interactions of Rearing Experiences and MAOA Genotype in Rhesus Monkeys" that will appear in the May 1st issue of Biological Psychiatry, researchers found that a rich social environment could protect monkeys from the negative effects of a gene polymorphism linked to anxiety. A press release summarized the research as follows:

There are some circumstances in a child's development – such as abusive parenting – that everyone would agree constitutes "adversity." This study suggests, however, that other, more subtle features of the broader social environment influence development, and that genes that affect our behavioral responses are sensitive to these influences. So even though an infant may be reared with its nurturing mother, the relative absence of other social partners, for both the mother and the infant, can result in the infant developing an anxious style of responding to challenges, particularly if it possesses a "risky" genotype.

Of particular significance, said senior author John Capitanio, Ph.D., is "that animals that were raised in rich, complex settings with mothers, other kin, and peers, were completely protected from the potentially deleterious effects of having the 'risky' form of the MAOA gene."

This isn't to say that genes aren't important--because they most certainly are. But we're just touching the tip of the iceberg with our understanding of how our genes interact with our environment. Any biological children that I have will be at a higher risk of developing an eating disorder. That's just reality. But I can make sure that they understand the dangers and futility of dieting, that they understand the true meaning of healthy eating and the range of shapes and sizes that human bodies come in. I can also step in at the first sign of trouble and make sure that he or she begins eating properly and maintaining an appropriate weight. I don't know for sure that this will protect them, but it can't hurt to try.

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Gwen said...

This issue is particularly interesting to me. I have a genetic mutation, a BRCA2 mutation, which makes me more susceptible (a lot more susceptible) to breast and ovarian cancer. Even with this mutation there are steps I can take to prevent getting cancer. I had a mastectomy, which almost eliminates my chance of breast cancer. When I'm done having kids, I'll take my ovaries out. I also have had anorexia, so obviously there is a susceptibility in my genetic make up to an eating disorder. But I can also take steps to prevent the illness. I can eliminate dieting from my behavior. I can have a doctor closely monitor my weight, to catch any illness early. So, yes genetic susceptibility sucks and makes life more difficult. But it doesn't have to be a predictor of illness. We can use this knowledge to protect ourselves from illness. Great post, Carrie, as usual. You always have me thinking!

Jennny said...

This is a cool post. I was just talking to someone the other day who was arguing that the media was 100% responsible for eating disorders - I tried to explain to her that it was way more complicated than just "kate moss did it!" but they were kind of stubborn. Thanks for this post I'll pass it on.

Anonymous said...

Great explanation of a complex subject--you're good at that!

Carrie Arnold said...

Aw, shucks! Thanks!

I love science writing- it took a while for me to find the right field, but it's a huge relief to finally know I'm in it!

Kim said...

Thanks for the post. This shed some light for me. I think about the gene/environment interplay quite a bit; and I worry about passing on the pieces of the ED puzzle to my future children (if I have them). Your last paragraph resonated with me. You're right -- my children may be more predisposed to an ED, but I can do whatever I can, environment-wise, to offset that.

Anonymous said...

Hi -

I was wondering if you would add my blog to your blogroll? It is about my own therapy-related experiences . . . thank you in advance!

- Marie

Crimson Wife said...

If you take a look at my family tree, it's full of anxiety- and depression-related problems. With me, it manifested as bulimia but I'm sure it's the same underlying genetic predisposition as my brother's and my mom's depression, my aunt's and my grandma's anxiety disorder, my great-grandfather's alcoholism, and so on.

It may be environmental that it manifested in eating and body image issues, but there's some biochemical imbalance that left me vulnerable.

Carrie Arnold said...

Crimson Wife,

You're absolutely right- no amount of environment can ever get rid of your inherent vulnerability. But having that vulnerability doesn't mean that you're doomed to be ill for the rest of your life, either. I am trying to learn how to live with my biology and my vulnerabilities.

Clare said...

great post. I really appreciate reading some scientific information on this matter. sometimes personal experience and others' opinions just aren't enough. Enjoy your weekend!

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I'm a science writer, a jewelry design artist, a bookworm, a complete geek, and mom to a wonderful kitty. I am also recovering from a decade-plus battle with anorexia nervosa. I believe that complete recovery is possible, and that the first step along that path is full nutrition.

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nour·ish: (v); to sustain with food or nutriment; supply with what is necessary for life, health, and growth; to cherish, foster, keep alive; to strengthen, build up, or promote


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