The neurobiology of anorexia
Updated: Nov 13, 2019
Anorexia, like all eating disorders, tend to start in adolescence. The thing that triggers our eating disorder varies, the comments from a family member, bullying at school, the end of a relationship, and it begins when we fail to eat enough to meet our energy needs, placing us in a state of what we call negative energy balance,or energy deficit – burning more calories than weeat. For some, a weight-loss diet can precipitate the eating disorder; for others, it can be intensive sports training, a growth spurt, an illness, stress levels or maybe an operation that stops you being able to eat for a while.
For most people, being in a negative energy balance is profoundly uncomfortable. Being on a diet tends to make 'normal' people feel horrible: tired, irritable and cranky, but those of us with a predisposition for anorexia have a completely different experience. Starvation makes us , weirdly, feel better.
Walter Kaye’s fascinating research work with women who have recovered from anorexia nervosa (2008, the neurobiology of anorexia and bulimia) found unusually high levels of a neurotransmitter called serotonin in the cerebrospinal fluid that 'bathes' the brain, and he believes these high levels were likely present before the onset of anorexia.
We know that low serotonin levels are linked to depression, high serotonin levels create a state of chronic anxiety and irritability. Research shows that approximately as 75% of those with anorexia had suffered from an anxiety disorder before the onset of their eating disorder, most commonly social anxiety and OCD. It is this anxiety that Kaye suggests makes some much more vulnerable to anorexia.
The body synthesises serotonin from the amino acid tryptophan, which we get from our food; so, eat less food, you get less tryptophan,and less tryptophan means a reduction in serotonin. So for those of us with this predisposition for anorexia, the starvation reduces the anxiety and irritability associated with our high serotonin levels. We find that we feel 'better'.
It doesn't just stay there, though. The brain responds to this reduction in serotonin by increasing the number of receptors to wring out every last drop of this neurotransmitter; This results in an increased sensitivity which leads to a return of the unpleasant, negative feelings and drives us to cut back even more on our food intake. Our attempts to return to something like normal eating patterns flood our hypersensitive brain with a surge of serotonin, causing panic, rage and emotional instability. Anorexia is, in effect, locked into place.
This doesn't have to make recovery from anorexia impossible, even if this process has been locked into place for many. many years.
Nutritional rehabilitation remains the best indicator of a robust recovery, and because of the innate neuroplasticity of the brain, the very structure of the brain can be positively effected by the right interventions and by consistent, determined hard work.
Neurobehavioural interventions to improve emotion regulation skills, such as the work by Amit Etkin, is increasingly being considered especially helpful to people with mood and anxiety disorders (such as those commonly associated with anorexia).
The aim is that with sufficient training, you can rehabilitate the dysfunctional circuitry, although it's not completely understood yet whether this works through a normalisation of abnormal circuitry, or by a process of the brain learning to compensate for the dysfunction.
Etkin has had positive results showing that internet-based training in skills to cognition,regulation, memory and positivity result in improved executive function and reduced emotion reactivity, with accompanying brain changes in amygdala (this is the centre for that fear, anxiety, irritability we feel when faced with food in recovery) and also in the brain's salience network, (which is responsible for detecting behaviourally relevant stimuli and coordinating neural resources in response to these stimuli- over aware of what's on other people's plates, much?).
All this research is enlightening and equally encouraging. No matter how 'inevitable' your eating disorder may at some point feel, your recovery could be just as inevitable