How does anorexia affect the brain?

How does anorexia affect the brain?

One of the biggest ways AN impacts the brain is through the limited diet often adopted by people struggling with the condition.

This eating pattern generally deprives the brain of essential nutrients, vitamins, and minerals, which could lead to cognitive impairments like confusion, difficulty concentrating, or problems with working memory.¹¹

A lack of glucose, also brought on by a limited diet, can be problematic as well. The brain requires much of this energy source to perform normal functions, and without enough of it, issues can develop around attention span and memory.¹²

But on top of impacting the way people think, anorexia nervosa can also impact the brain itself, resulting in a number of brain abnormalities.

Altered brain structure

For decades, research has indicated that AN can have an impact on brain cells and brain structure. As far back as 1985, studies found patients with anorexia nervosa had a widening of the gaps between the folds in the cerebral cortex, and a shrinking of the folds themselves.¹

These types of changes are significant, as the folding pattern allows the cerebral cortex—the area of the brain responsible for the higher-level processing involved in language, reasoning, and decision making, among other functions—to take on more surface area. And while these folds are generally set at birth, abnormal folding patterns have been tied to a number of serious neurological conditions, including epilepsy, schizophrenia, and autism.⁹

More recent findings have connected AN to changes in the ventricles of the brain. This group of cavities in the center of the organ are responsible for producing, holding, and circulating cerebrospinal fluid (CSF), a media that nourishes, protects, bathes, and supports healthy neural tissue.¹

Using magnetic resonance imaging (MRI) machines to create brain scans, scientists discovered an enlargement of the ventricles and higher CSF volume in patients with anorexia nervosa.³ This type of scenario can put excess pressure on the brain, leading to potential complications.¹⁰

Loss of brain tissue

Over the years, a number of studies have also linked anorexia nervosa to a loss of normal brain tissue volumes.

The brain is primarily made of two types of tissue: Gray matter and white matter. Gray matter makes up the outer layer of the brain and has a high concentration of neuron cells — those responsible for sending and receiving messages to and from the body. White matter also contains neurons, but they are coated in a layer called myelin. This allows messages between neurons to travel quickly and efficiently.⁴

MRI studies on people with AN have repeatedly shown significant shrinkage of gray matter volume. This brain development has been found to primarily impact the frontal lobe and left insula, regions of the brain that play important roles in regulating emotion, impulse control, attention, self-regulation, and social interactions.⁴

Researchers suspect that this may contribute to some of the cognitive and emotional issues often associated with anorexia nervosa, with some studies noting that these structural changes mirrored those involved in people with suicidality, autism spectrum disorder, and a range of anxiety disorders.^4,7

Can brain structure changes lead to anorexia?

Interestingly, some research has suggested that rather than causing changes to the brain, AN can be caused by structural differences in the organ.

One study on the matter found that alterations in the medial orbitofrontal cortex, insula, and striatum—areas of the brain tied to emotional processing, decision making, and the brain reward circuits, among other functions—were related to taste pleasantness and reward sensitivity in people with AN.

Researchers posited that these alterations might explain the food avoidance behaviors commonly seen in those who struggle with AN and other eating disorders that involve the restriction of diet.⁸

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Are brain changes caused by anorexia permanent?

Thankfully, much research has shown that changes to the brain brought on by AN are not permanent. In many cases, brain function, brain volume, and brain structure return to normal as someone undergoes weight restoration.

Alterations in the folding pattern of the cerebral cortex are one of the changes that have been found to subside with healthy weight gain. Gaps between folds shrunk down to normal size, while brain volume increased overall in one study on people recovering from AN.² Another look at those in long-term recovery found that their gray matter volume was similar to people of the same age who had never struggled with anorexia nervosa.⁵

These changes have been shown to happen relatively quickly, with one study showing just partial weight restoration over the period of three months resulting in increased thickness in brain tissue.⁶

Still, some research has indicated that the degree of brain shrinkage correlates with the duration of illness in people with AN, which is one more reason why early treatment for anorexia nervosa is so important.³