Overlap between anorexia nervosa (AN) and autism (ASD)

Individuals who have AN but not ASD can show signs of ASD behavoir during an acute phase of AN. According to research hunger makes the brain solely focus on the task of obtaining food, that as with other stressors, makes the higher cognitive functions shut down. It is known that starvation
intensifies autistic characteristics such as rigidity and obsession. Underweight individuals with AN portray similar behavior to individuals with ASD.

AN and ASD have a similar cognitive profile. The corresponding characteristics between the two are amongst others, rigidity in behavior and thinking, perfectionism, comorbidity and an increased rate of classification. In addition, there can be a decline in executive functions (in particular a lack of mental shift skill) and a lack of Theory of Mind (TOM). This is the ability of an individual to assign intentions, thoughts or feelings to themselves and to others. This means that in individuals with the above characteristics, the characteristics can often be attributed to this acute phase of starvation and not a presumption of possible ASD.

ASD-like behavior does not occur more frequently in women with AN without ASD than in women without psychiatric illness. In clinical practice this can mean that the presence of autistic behaviors such as difficulty with change and social skills, cannot be interpreted as appropriate to AN. In that case, a diagnostic examination of ASD is preferred, particularly with people with a long-term / chronic eating disorder.

When the result of the characteristics associated with ASS comply to the acute phase of starvation a woman with undiagnosed ASS who (long-term) is being treated for persistent AN runs the risk of not being diagnosed for ASD. Also, the recognition of ASD in women with AN can be overlooked
when behavior is manifested as extreme rigidity or obsessive interest in calories or movement. This missed diagnosis causes continued regular treatment protocols for AN, which does not take into account the existing ASD.