Transcript
I’m Dr Samuel Chawner, Research Fellow at Cardiff University Centre for Neuropsychiatric Genetics and Genomics, and today, I’ll be talking about two feeding and eating disorders, ARFID and pica [pause]. ARFID is short for avoidant/restrictive food intake disorder, and it’s a feeding and eating disorder that was introduced as a diagnosis to the DSM-5 Psychiatric Classification System in 2013. ARFID is marked by food avoidance and the restriction of food intake, however, ARFID should not be mistaken for fussy or picky eating, it is a serious condition. And as a part of the ARFID diagnostic criteria, symptoms have to seriously impact the individual in one or more of the following areas, which includes significant weight loss, compromised growth, serious malnutrition, dependence on nutritional supplements or tube feeding, and significant impact on psychosocial functioning.
ARFID differs from anorexia nervosa in that dietary restriction is not motivi – not motivated by body image or weight concerns. Avoidant and restrictive eating have long been recognised by Clinicians, but research and service development has been hindered by uncertainties in diagnostic classification. The lack of a formal and unified diagnosis until 2013 means ARFID research is still very much in its infancy, and very little is known about its epidemiology and etiology. Referrals for ARFID are increasing, but inpatient and outpatient clinics currently lack an evidence base to support individuals with ARFID effectively [pause].
Three main drivers have been identified for ARFID. Firstly, sensory sensitivity to food qualities may lead to avoidant and restrictive eating. This cau – could involve sensory aversion to the taste, look, smell, or texture of foods. Sensory sensitivities and rigid eating habits, which are features of ARFID, are often associated with autism. However, it’s important to recognise ARFID as a separate diagnosis from autism. Not all autistic individuals experience eating difficulties, and vice versa, not all individuals with ARFID are autistic. It has been hypothesised that sensory differences could be due to differences in taste perception, but the research needs to be done to back the – up this hypothesis.
The second driver for ARFID is a lack of appetite or lack of interest in food. Often individuals with ARFID can feel full very quickly during a meal, or may not feel as hungry as others. It has been hypothesised that this could be driven by physiological differences in appetite regulation, and differences in the functioning of reward pathways in the brain that influence how rewarding an individual finds food. The third driver of ARFID that’s been identified is the fear of potentially distressing consequences of food intake, such as choking or vomiting. This is often triggered by a traumatic event. However, it’s not clear why some individuals are more susceptible to long-lasting food avoidance following a traumatic event, such as food poisoning, as many of us experience unpleasant food related events. It could be that high baseline anxiety is a risk factor, indeed, many individuals of ARFID often have a co-occurring diagnosis of anxiety [pause].
Recent population studies have combined questionnaire and medical record data, have suggested a prevalence of one to 2%. This would suggest ARFID is as prevalent as autism, yet research and clinical awareness is comparatively lacking for ARFID. However, in clinical practice, ARFID is currently underdiagnosed. A surveillance study within the NHS found the prevalence of diagnosed ARFID to be three in 100,000 individuals. So there’s clearly a gap between the rate of diagnosis of ARFID and the populat – the rate – the prevalence of ARFID traits within the population.
ARFID is more commonly diagnosed in childhood, but this is partly because we don’t understand much about how ARFID presents in adulthood yet. In terms of gender differences, the findings are mixed. Some studies indicate an increased prevalence in males, whereas, other studies find no difference between male and female genders, and there has been a lack of research looking at prevalence of ARFID across other gender identities. What is clear from research studies, is that the incre – is the increased prevalence of ARFID within autistic individuals, with some studies finding one in two autistic individuals have ARFID. But it should be emphasised that the exact prevalence does vary a lot across research studies [pause].
Pica is a feeding and eating disorder, defined as “the recurrent intake of non-nutritive and – or non-food substances, for instance, paper, soap, coal or wood.” To receive a diagnosis, pica behaviours have to be present for at least one month, they also have to be inappropriate to the development stage of the individual. For instance, often babies will put whatever they have in reach in their mouth, this wouldn’t be classed as pica. To receive a diagnosis, and the pica behaviours have to occur outside cultural norms or traditions.
It is important to study pica, as those who experience pica frequently have adverse health and psychosocial outcomes. Individuals with pica are at increased risk of significant medical consequences, such as dental enamel erosion, increased risk of infection, anaemia, gastro-intestinal obstruction, and, also, risk of poisoning. In addition to medical risks, pica is also linked to psychosocial functioning, it impacts family relationships and can lead to less social contact with peers [pause].
Pica can occur at any point across the life course, but onset is most commonly during childhood. But it should be recognised that pica is also common during other periods of the life course, for instance, it’s common during pregnancy, when there can be strong cravings for non-food substances. Common co-occurring conditions with pica include autism and developmental delay, and children from lower socioeconomic backgrounds are more likely to develop pica. And in research that I’ve done, looking at the Bristol Avon Longitudinal Study of Parents and Children population cohort, I haven’t found any evidence for gender differences for pica, but confirmed the previous link between pica, autism and developmental delay [pause]. Pica can occur within the context of anorexia nervosa, where the individual uses the eating of non-food substances to avoid putting on weight, but still gets the sensation of feeling full. However, longitudinal research is needed to investigate if pica itself leads to the development of other eating disorders [pause].
In the UK, there are currently no National Institute for Healthcare Excellence guidelines for ARFID, because of an absence of sufficient research. That’s not to say there hasn’t been initial intervention research. Early evidence highlights that food exposure, psychoeducation, anxiety management and family therapy are beneficial for the treatment of ARFID. However, studies reporting on psychological interventions have be – often been characterised by small samples and differences in how outcomes have been measured.
For pica treatment, behaviour modification programmes have often been used to redirect an individual’s attention away from the non-food object and towa – reward the choice of appropriate food items. Also, medication for managing behavioural problems can help reduce the urges and impulses to eat non-food items [pause].
Initial evidence has indicated genetics plays a major role for the development of ARFID. The first twin study of ARFID, involving Swedish twins, has found that approximately 79% of the risk of developing ARFID may be explained by genetics. They did this by comparing the prevalence of ARFID between monozygotic twins, who share all their DNA, and dizygotic twins, who on average are 50% related. The heritability of ARFID is on par, or in many cases higher, than that for other psychiatric and neurodevelopmental conditions, highlighting the importance of genetics. However, it should be recognised there needs to be more research in this area. There has only been two studies so far, looking at the genetics of ARFID.
For pica, there has been very little genetic research, but there is evidence that for some rare genetic conditions, such as Prader-Willi syndrome, there’s increased rates of pica.