Biological causes of anorexia nervosa
For many years, doctors believed AN was primarily a sociocultural disorder or one that resulted from environmental and social conditions such as pressure to look a certain way and the prevalence of unrealistic body image in popular culture.2
However, advances in genetic research have led to a closer examination of the causes of anorexia nervosa, revealing several biological elements that may also play a role.
Genetic inheritance
Several studies have found that aspects of anorexia nervosa are heritable, meaning they can be genetically passed down between generations.
Earlier studies on the subject looked at the prevalence of AN within clusters of biologically related people and found a significant connection compared to control groups. The reports noted a seven to twelve-fold increase in anorexia nervosa among the related groups—particularly in women.2
To further differentiate between nature and nurture, further studies were done on twins. These concluded that anywhere from 58%-76% of the risk of developing AN could be attributed to genes.2 Other studies reported an even wider range, citing anywhere from 28%-74% of AN cases to genetic susceptibility.3
It's important to note that AN isn't passed down from generation to generation. Certain traits, including specific responses to stress, are passed on, making people more susceptible to developing the condition.
Puberty
Puberty is considered a primary risk factor for developing a number of eating disorders, including anorexia nervosa.12 Several issues combine at this critical time to raise the risk of developing AN or disordered eating behaviors.
The most significant risk factor from a biological perspective is the enormous number of physical and physiological changes that take place during puberty. Fluctuating hormones can lead to sudden weight changes, mental health issues, or other factors that can contribute to the development of AN.12
Similarly, puberty can be a time when many genetic factors are triggered, whether from these hormonal and biological changes or environmental experiences common to pubescent people.12 A preoccupation with body shape and weight and related low self-esteem often starts during this time.12
Psychological causes of anorexia nervosa
Anorexia nervosa may manifest in a very physical way, but the condition is, at its core, a mental health disorder. As such, a number of psychological factors can contribute to the development or maintenance of AN.
Personality traits
Like most other aspects, personality traits can be inherited, shaped by the environment, or both. But, in any case, certain personality traits may raise someone's risk of developing AN.
A number of reports have found the way a person physiologically reacts to stress could contribute to disordered eating behaviors. Negative emotionality and harm avoidance, in particular, have been associated with anorexia nervosa.2 Traits, such as perfectionism, cognitive inflexibility, or difficulty with change, have also been connected to AN.1,13
These traits have been found to persist even after a patient’s recovery, leading those studies to conclude these traits may be fixed and are one of the direct anorexia nervosa causes.2
Comorbidity
Comorbidity describes when one person struggles with two or more simultaneous medical issues. And many mental disorders have been found to have a comorbid connection to AN.
The correlation between anxiety disorders and anorexia is especially strong. Obsessive compulsive personality disorder (OCPD), separation anxiety, and overanxious disorder, as well as phobias and panic disorder, have also been found to share some degree of familial transmission and have all been linked to higher rates of anorexia.2
Depression can also co-occur with anorexia nervosa. Though not tied as closely to AN as anxiety disorders, major depressive disorder—which is also often inherited—has been considered a relative risk factor for AN.2
Environmental and social causes of anorexia nervosa
Biology is only one piece of the puzzle. The environment surrounding a person is equally as important in the development of a disorder.
The cause of anorexia was traditionally attributed almost exclusively to environmental factors. And while an increasing number of biology-focused studies are adding nuance to that idea, it’s still believed many potential causes of anorexia nervosa aren’t biological.
Trauma
Unfortunately, one of the biggest risk factors for developing anorexia nervosa or other eating disorders is the experience of trauma, especially sexual trauma.
Anorexia nervosa has been connected to traumatic experiences spanning a spectrum, including:4
- Sexual abuse
- Physical and emotional abuse
- Teasing and bullying
- Divorce
- Loss of a family member
Nearly a quarter of all participants in one study were found to fit the official criteria for post-traumatic stress disorder.4
Social identity
While white females between 13-19 have historically been considered the most at-risk for anorexia nervosa, further research has shown how the disorder occurs in other social, racial, and gender groups.7,8
One report found that transgender college students were found to be at least four times as likely to experience disordered eating than their cisgender classmates.6 And several studies have also drawn a link between people struggling with anorexia and people who have autism.2
Athletes were also found to be significantly more likely than non-athletes to screen for eating disorder behaviors—and less likely to seek treatment for these issues.5
A number of reports are currently being conducted to bridge the information gap on AN among diverse racial and ethnic groups, who have historically been underrepresented in most studies.
Peer pressure and role modeling
Weight-related teasing or critical comments about weight, especially from parents, are both considered potentially triggering scenarios for developing AN.9 Indeed, parental role modeling has long been studied as a contributing cause of anorexia nervosa, with a string of analyses finding a correlation between the eating/dieting habits and weight concerns of mothers and their children.9
Of course, this is not always the case. People are sometimes influenced by peers, picking up on a number of less-than-healthy social cues from friends.
Studies looking at social pressure as a cause of anorexia show that people may be heavily influenced by a peer group that emphasizes the importance of appearance and intentionally migrates toward these groups.2,10
Once embedded, the cultural value of thinness—emphasized in most forms of popular media and often learned by children at a young age—can drive competition within the group, where members will compare weights, diets, and other aspects of appearance and generally create a self-reinforcing echo chamber for these ideals.10
Treatment of anorexia nervosa
Anorexia nervosa can be a devastating mental illness, but there are a number of treatments that may be able to help.
Addressing the various causes of anorexia requires a multi-faceted treatment approach, which includes mental and behavioral therapy, nutrition counseling, physical therapy, and other types of care. In general, a course of treatment for AN should focus on:11
- Stabilizing weight loss/improving calorie intake
- Restoring nutrition, physical health, and food intake
- Addressing the causes behind the disorder, including distorted body image
- Learning healthier long-term coping strategies for the identified stressors
Some combinations of these therapies are successful in treating many people struggling with anorexia nervosa. Although the condition can be very dangerous and life-threatening, it’s possible for people to make a full recovery with the right kind of care.
