Though allergies are certainly not “all in the mind”, personality factors may play a role in them. By Marc Wilson.
In the 1990s, when my daughters were born, there was inconsistent advice on gestating non-allergic babies. One of said daughters has a dramatic allergy to several tree nuts – cashews and pistachios, but not peanuts or almonds. According to the FARE (Food Allergy Research & Education) website, nut allergies are the most common type of food allergy.
So, while raising our son 11 years later, we followed the early-2000s zeitgeist and avoided nuts because of the 50/50 record of allergies. The result? The lad is allergic to peanuts, cashews, and some other nuts, but not almonds. Grrr.
Currently, our Ministry of Health recommends nuts as a part of a healthy pregnancy diet, and this is backed by research suggesting an association between eating nuts in pregnancy and producing nut-allergy-free sprogs.
Which leads to today’s slightly facetious question – is there an allergic personality? I don’t mean people with personalities that make others come out in hives, but whether personality is associated with having (or not having) allergies.
Suggestions of some kind of connection between psychology and allergy have been around for more than a century. In 1906, German psychotherapists asserted they had caused an inflammatory reaction using hypnosis, and 25 years later, others reported “curing” hay fever and asthma using the same method.
In the 1930s and ‘40s, research shifted to psychological factors that may be a potential foundation for allergies – if they’re at least partially in the mind, but not everyone experiences them, what are the psychological differences between sufferers and non-sufferers?
Although one of these early studies purported to show that allergy sufferers tended to be more intelligent, others claimed a correlation between allergies and “neurasthenia”, a condition that, the internet tells me, is characterised by “lassitude, fatigue, headache and irritability, associated chiefly with emotional disturbance”.
For reasons that aren’t entirely clear to me (but may reflect less rigorous attention in the past to ethical standards) many of these studies involve children. For example, Bernard Reiss and Olga De Cillis got more than 100 paediatric allergy clinic patients and a similar number of elementary student controls to complete then-standard questions about personality, and looked for patterns related to their specific complaints. The results of this 1940 study were much more mixed than I would have expected – on the one hand, allergy sufferers were notably more extroverted and assertive than controls, but they also reported more emotional instability. Interestingly, different allergy profiles were associated with different levels of extroversion, assertiveness and emotionality – people with skin conditions tended to come out more extrovert and stable.
Anyone whose summer has been ruined by hay fever knows that, while we can certainly find case studies of psychosomatic allergy, allergies are generally not the product of an overactive imagination. The problem with these studies is they tend to be correlational and, as good lay scientists, you know that correlation is not necessarily causation. If there are psychological differences between people with allergies and controls, it can also mean that chronic allergy experience affects our psychology.
For some partial disentangling, let’s turn to work by just-minted professor Tamlin Conner and colleagues at the University of Otago. Conner specialises in getting people to record daily diaries, usually over a few weeks, and correlating their experiences with personality traits. In a 2018 study, 108 adults with a diagnosed allergy first completed measures of personality, then a two-week daily diary. In this study, extroversion was a bit player, and emotionality was unrelated to reaction frequency, stress or mood. However, allergy sufferers who reported greater conscientiousness experienced less positive mood. Those scoring high on “openness to experience” wrestled more with day-to-day challenges, such as finding safe foods or embarrassment. Why? Maybe because open people tend to explore their environments more and therefore encounter more allergy issues.
Of course, it would be tasteless to speculate about psychology and nuts.
