An Association Between Anorexia and Month of Birth?

How could being born in the spring season increase someone’s risk of suffering from anorexia nervosa? Scientists are not exactly sure, but a recent study provides evidence toward an association between a risk of anorexia and when exactly people are born throughout the year.

We’ve all heard of anorexia, whether we’ve known someone who has suffered from it or heard information about it on the news when some celebrity is claimed to be anorexic. Regardless, anorexia has no true cause. It is estimated that up to 3.7% of all women will suffer from some degree of anorexia nervosa at some time throughout their life. According to the United States National Institute of Mental Health, about .3% of men will develop this form of eating disorder as well.

Anorexia actually has one of the highest mortality rates of all mental illnesses, yet professionals do not the cause or even the risk factors involved in its development. Researchers have proposed a number of possible causes and risk factors such as a chemical imbalance in the brain, genetics, brain dysfunction, maternal depression, lack of self-esteem, pressure to be thin from society, perfectionism, and child abuse are just a few.

A new study has been brought to light from the Wellcome Trust Centre for Human Genetics at the University of Oxford, which suggests that the time of year in which someone is born may predispose that person to develop anorexia later in life. This study is the largest study that addresses this question. Other studies have been conducted, but included too few subjects.

For this study, researchers gathered information including the date of birth for exactly 1,293 people that suffer from anorexia and found that a higher number than normal (an excess of 15%) were born in the months of March through June, while fewer than normal (a deficit of 20%) were born in the months of September and October. Lead investigator for this study, Dr. Lahiru Handunnetthi, stated that the susceptibility toward anorexia nervosa seems to be significantly influenced by the month in which people are born, being clearly higher for those born in the spring months and lower for those born in the fall.

Previous studies have already shown that the month a person is born may play some role in whether or not they will develop a mental disorder. A recent study from the Wright State University noted that the season of birth may actually impact whether or not someone will be more likely to develop schizophrenia. It was found that people born throughout the spring and fall are at a higher risk.

Studies have also proven that other mental disorders such as depression and bipolar disorder is also more common in those born in the months of spring as well, therefore proving that the finding involving anorexia may not be too surprising. The question now is why exactly and how a season of birth could have such an impact on mental health. The researchers are beginning with some possibilities such as environmental factors playing a role since we already know that changes of the seasons can affect our general well-being in terms of temperature, exposure to sunlight and vitamin D, maternal nutrition, and also infection exposure could all be possible factors. Now researchers have to focus though on why anorexia specifically seems to directly affect those born in the spring months.

References:

Schwartz, P. Medical Hypotheses. 2011. Mar. 5.

Mitchell, D. Risk of Anorexia Greater for those Born in the Spring. 2011.