Studies headed by Howard Steiger, Ph.D. of the Douglas Hospital Eating Disorders Program and Research Centre have shed light on how a complex interplay between genetic, environmental, and psychological factors may occur to give rise to anorexia and bulimia nervosa. Efforts such as these are of critical importance when one considers that in Quebec alone, 30 000 women (and some men) struggle with these eating disorders (EDs). In fact, when less stringent diagnostic criteria are applied, the numbers reach 90 000 young women, or more.

On the surface, EDs appear quite simple--individuals with anorexia merely do not eat, while bulimia sufferers eat enormous amounts of food and then purge. Although true, this depiction does not begin to describe the complexity that defines EDs. Findings from Howard Steiger’s research certainly support this notion. He explains that both anorexia and bulimia nervosa are characterized by “maladaptive attitudes and behaviours around eating, weight gain, and body image and are related to disturbances in impulse control, mood, and interpersonal functioning,” but that important distinctions between the two exist.

Anorexia Nervosa involves self-imposed starvation fuelled by a gripping phobia of becoming fat resulting in dangerous emaciation. For some people, this means exerting compulsive and strict control over food intake, while for others, the pattern is one of binge-eating episodes followed by purging. Thus, anorexia tends to be about “over control” and in both subtypes of the disorder; the individual’s self-worth is literally measured on a scale.

Bulimia Nervosa, on the other hand, is diagnosed in relatively normal or overweight individuals and is characterized by dietary dyscontrol in which prolonged restraint and/or compulsive dieting can lead to binge-eating episodes coupled with frantic compensatory behaviours, which include, vomiting, over exercising, and the misuse of laxatives. Thus, bulimia is most related to “under control”.

So what causes EDs? It was long thought that they arose from western society’s obsession with beauty and thinness, and/or faulty parenting. While sociocultural pressures certainly have a key role to play, recent evidence has called into question the idea that EDs are solely extreme versions of “normal” dieting. Howard Steiger and his team have shown that certain biological factors probably render some people especially vulnerable to becoming anorexic or bulimic.

When we eat, we provide our brain with the critical ingredient in the recipe for a chemical messenger (neurotransmitter) known as serotonin. Without food, our brain simply cannot make serotonin. This neurotransmitter plays an important role in multiple brain systems and is known to be involved in the regulation of mood, impulsive behaviours, our response to stress, and most importantly with respect to EDs, satiety, and the regulation of eating behaviour. In both animals and humans, increased serotonin signaling is associated with reduced eating, whereas decreased serotonin activity results in compulsive or binge eating. Sound familiar? Howard Steiger and his team thought so.

Accordingly, they undertook a series of studies that examined the relationship between serotonin and EDs. With the knowledge that variations in our serotonin activity are under genetic control, the Douglas Hospital research team wished to determine if there were differences in serotonin regulation between individuals with or without an ED. They not only found this to be true but also uncovered findings that suggest how certain individuals who carry specific versions of genes that encode for serotonin activity in the brain could be more susceptible to developing an ED. “The way it looks is that environmental pressures to diet switch on biologically based vulnerabilities”.

These genetic findings may in part explain why EDs tend to run in families, or why certain ED forms (like bulimia) occur especially often in people with high degrees of impulsivity or mood instability. It may be that the trait of impulsivity, because it is associated with tendencies towards low serotonin activity, also makes people very vulnerable to problems of satiety (or binge eating) should they diet.

It is important to note however, that genetic factors alone do not account for the occurrence of EDs, and having the serotonin genetic variation does not automatically lead to the development of an ED. Environmental factors such as life stresses, childhood abuse and social influences play an important role. Howard Steiger argues that a “causal collision” of sorts occurs between biological, social, developmental, and psychological conditions. “EDs provide a perfect example of how the environment can activate a genetic vulnerability that might otherwise not speak”. In this case, social pressures to be thin and to diet may switch on the biology.

In the end, what do these results imply with respect to the treatment of EDs? Howard Steiger is one of the only individuals that can answer this question, at least in Quebec. This is because his Eating Disorders Program run out of the Douglas Hospital is the only large-scale ultra-specialized clinical, teaching, and research program involved in the treatment of ED in the province. Given this setting, Howard Steiger is able to directly apply advances in research to clinical populations in the hopes of improving treatment methods. His ability to go from the clinic to the lab and back to the clinic has surely contributed to the strength and success of his centre. One of the Steiger’s hopes, given research showing people who develop an ED to have many different characteristics and even genetic tendencies, is to be able to develop more highly individualized treatments that are more responsive to individual needs.

Other important mandates of the program are raising public awareness and providing invaluable information and training to community based intervention programs. In addition to the current Eating Disorders Program at the Douglas Hospital, a new Day Hospital opens June 3, 2004, where people with EDs will be able to receive full-day treatments but then return home. This may help Howard Steiger and his team to reach more of the 400 plus individuals with an ED currently on a waiting list for treatment.

Other than advancing our knowledge with respect to the underpinnings of EDs, Howard Steiger’s studies may help to dispel some of the misconceptions about people with EDs, often depicted as easily influenced, self-centered perfectionists. Steiger’s work shows that biology and genetics, and not “strength of character”, is likely to play an important part in explaining why one person falls prey to an ED, whereas another does not.

By Tania Elaine Schramek