Gabor Szendi:
Asthma and the right hemisphere

Left and right hemispheres are different, not only in their cognitive styles but in controlling the immune system.

 

 

Attention has been focused on the left-handed

Left-handedness has been attributed sinister meanings since ancient times, and not so long ago it was customary to teach left-handed children to use their right hand. In other words, left-handedness was initially only associated with 'abnormal' use. Then it began to be noticed that children who were re-educated to use the right hand were more likely to have learning disabilities, stuttering, and dyslexia. We now know that this has nothing to do with the re-education process, but that it involves left-handedness itself.

The potential for left-handedness to be associated with immunological disorders was noted by two neurologists, Norman Geschwind and Peter Behan. In two studies in 1982, they found that left-handed people were 2.5 times more likely to have autoimmune diseases, and 12 times more likely to have various developmental disorders such as learning disorders, stuttering, dyslexia (Geschwind and Behan, 1982). It was also soon confirmed that atopic diseases, that is, allergic diseases characterized by high IgE levels such as eczema, hay fever, asthma, food allergy, etcetera, are extremely common among left-handed people (Geschwind and Behan, 1984). In medicine, the time of discovery is always of great importance: the relationship between atopic disease and left-handedness would have been difficult to recognize in the past, as the incidence of atopy only began to increase markedly around the mid-20th century. In Norway for example, the prevalence of asthma was 0.4% among children in 1948, and 20% in 2005, that is, the proportion of asthma patients increased by 50 times (Gibson et al., 2013).

Geschwind, Behan, and Albert Galaburda teamed up to create their theory, which became popularly known as the GBG model. This is that depending on its amount, testosterone slows the growth of the left hemisphere in fetal life (Geschwind and Galaburda, 1987). Because the left hemisphere contains the brain areas responsible for speech, numeracy, reading, and focused attention, this immediately explained why boys are more likely to experience delays and disorders in these functions. If the testosterone effect is too strong, the left hemisphere lags behind enough to produce right hemispheric dominance, often leading to left-handedness, or two-handedness. By right or left hemispheric dominance we mean that one hemisphere is constantly more active than the other. For most people, the left hemisphere is the more active. Researchers explain immunological problems by saying that testosterone also slows down the development of the thymus, which plays an important role in recognizing its own tissues. Although so-called cellular immunity is unrelated to atopy, intensive research has nevertheless confirmed the relationship between right hemispheric dominance and atopic disease. That is, the relationship is explained by something else. It is important to keep in mind that right hemisphere dominance is not always associated with left-handedness, and that atopic propensity, as indicated by high IgE levels, is not necessarily manifested in atopic disease. So many left-handed non-atopic patients, and some right-handed atopic patients, have right hemisphere dominance.

Atopy and personality

Another line of research has shown a relationship between personality traits and certain psychiatric conditions and atopic diseases. Children who are shy, inhibited, retreating, or heavily introverted are much more likely to have hay fever and asthma than liberated, extrovert children (Bell et al., 1990; Kagan et al., 1991). Other studies have found a close relationship between depression and atopic disease (Bell et al., 1991). Studies have found people with asthma (Fernandes et al., 2005) and people with atopic skin disease (Kim et al., 2006) to be anxious and shy. In a Finnish study, a 31-year follow-up found that atopic patients (people with asthma, hay fever and eczema) were three times more likely to have depression requiring hospitalization than non-atopic patients (Timonen et al., 2001). Because a timid temperament is a biological trait, it was obvious that there must be something in common in the biological determination of personality and immune problems.

Is left handedness an advantage or a disadvantage?

Analysis of fossil finds or cave paintings has shown that left-handedness has always been present in human evolution. However if left-handedness is associated with learning and developmental disorders and a tendency to immune disorders, why hasn't this feature been screened out over millions of years? In order to answer this question it is important to distinguish between normal, and pathological left-handedness, as this issue also strongly distorts the research results. Pathological left-handedness is caused by fetal developmental harm and disorders, which are largely due to modern-day problems, just as various illnesses are a consequence of the changed lifestyle of the 19th and 21st centuries. If we assume that left-handedness occurs in all peoples, we must also assume that left-handedness was not eliminated by selection factors, but maintained. That is, being left-handed had some advantages. For example, left-handed people are better at hand-to-hand cooperation, so in those times when tool making was important, left-handed people had an advantage. Left-handed people are also more creative and better in the right hemisphere ancient functions such as music. Today, left-handedness has been an advantage in sports, and long ago in combat (Faurie and Raymond, 2013). According to some studies, left-handed people are socially more successful and wealthier (Llaurens et al., 2009). In any case, it is a thought-provoking fact that 8 of the last 15 US Presidents were left-handed.

What does the brain have to do with atopy?

The two research trends meet in the results of brain research.

The different emotional characteristics of the two hemispheres have been demonstrated by a variety of approaches. In patients with hemispheric brain injury, data obtained by anesthetizing one half of the brain, and examining pathological crying or laughing, clearly demonstrated that the left hemisphere is specialized in the perception and experiencing of positive emotions, and the right hemisphere is specialized in the perception and experiencing of negative emotions. The right hemisphere performs a 'watch' function, and it is informed of everything tenths of a second before the left, because it is a danger detector. It has also become clear from later research that the left hemisphere is responsible for proximity, that is, reward-driven behavior, which manifests itself as the personality traits of curiosity, openness to new things, liberality, and immediacy. In contrast, the right hemisphere is responsible for behavioral inhibition and avoidance behavior, which is characterized by personality traits such as inhibition, shyness, increased anxiety, and a tendency to depression (Szendi, 2001). Richard Davidson and Nathan Fox have shown in infants that EEG-dominated right hemispheres are the forerunners of inhibited anxious personality, and in adulthood such people are more prone to anxiety disorders and depression (Szendi, 2001).

The results explain the old experience of the existence of an 'atopic' personality, which at the same time clears the ground for speculation which regarded asthma as 'suppressed crying', or tried to interpret atopic symptoms on a psychic basis.

Two other interesting questions arise. One is: due to what immunological effects does the right hemisphere dominance predispose atopic diseases? The other question is most likely to be of concern to those suffering from such a disease, or have a relative who is: why do stress situations exacerbate atopic symptoms?

The immune system and the brain

The GBG model is based on the empirical evidence that left-handedness, or more broadly, right-handedness, predisposes to immune disorders, that is, autoimmune and atopic diseases. Given the different functions of both hemispheres, it is not surprising that hemispheric neural effects also affect immune functions differently. Studies have shown that the left hemisphere stimulates cellular immunity, whereas the right hemisphere inhibits it by blocking the left hemisphere. In other words, people dominant in the left hemisphere are more protected - for example - against cancer, and the old observation that depression predisposes to cancer is explained by the fact that increased right hemispheric activity reduces cellular immunity (Stoyanov et al., 2012).

IgE, which plays a major role in atopic diseases (see box), is a 'product' of the humoral branch of the immune system. Studies have shown that IgE levels are much higher than average in the case of right hemisphere dominance (Hassler and Gupta, 1993). When the body encounters an allergen to which it is sensitive, the allergen-associated IgE molecules trigger an inflammatory reaction in the body because the allergen is considered as 'attacking'. Those who will eventually become an atopic patient can be understood from the following:

Interactions between immune actions and the brain are bidirectional. On the one hand, when the brain senses stress, it can stimulate immune defense. On the other hand, it is also important to keep the immune response under control so as not to turn it against the body, as seen in autoimmune and atopic diseases. One of the regulators of overactive immune response is the known stress hormone, cortisol.

An interesting test method showed that cortisol levels are controlled by the right hemisphere. Subjects were fitted with contact lenses that obscured either the left or right field of vision. In fact, the left field of vision of both eyes projects into the right hemisphere, and from the right field of view to the left. This way it was possible to determine which hemispheres watched a shocking or neutrally emotional film. 87% of people had elevated cortisol levels when they watched an emotionally stressful movie with their right hemisphere. However, a small proportion of subjects had elevated cortisol levels when the view was projected into the left hemisphere. Thus, in these individuals, cortisol control was shifted to the left hemisphere, but the immune response to stress continued to be directed by the right hemisphere. Various physical experiences could also be observed (Wittling and Schweiger, 1993). The most common cause of physical complaints was the separation of stress, and immune response. The right hemisphere gives a greater inflammatory response to identical stress stimuli (Koch et al., 2006), but for most people cortisol keeps this in control. However in some people with right hemisphere dominance, the immune response when exposed to an allergen is not followed by an increase in cortisol levels, as these are regulated by the left hemisphere. This explains the higher incidence of autoimmune and atopic disease among left-handed people, and also explains why symptoms increase in these diseases due to stress: a lack of 'braking'. This is not just a theory: atopic patients have repeatedly been shown to have a much lower cortisol response to stress (Buske-Kirschbaum et al., 2010).

 

Destiny or avoidable?

Various allergies were first reported in the medical literature in the early 19th century. The explosive spread of atopic diseases began in the 1960s. Many believe that the cause lies in environmental damage, but the growth has occurred even where there is no industry (Szendi, 2011). The real cause is a change in nutritional and medication habits that cause cells in the gut wall to become less closed and to develop so-called leaky gut syndrome. Numerous studies have shown that in various atopic diseases, the allergen enters the body through a 'holey' intestinal wall and an immune response against the allergen is developed throughout the body, which in turn is usually seen in local (skin, lung, nose, eye, etc.) symptoms ( Liu et al., 2005).

Unbelievers need only think about how eating peanuts or soy can cause asthma attacks: the answer is 'leaky gut' syndrome (Hijazi et al., 2004). The modern diet contains many nutrients that cause leaky gut syndrome (such as gluten or WGA lectin from cereals). However not everyone will be atopic, because the prerequisite for this is high IgE levels and abnormal hemispheric dominance. The atopic course is the sequential onset of allergic diseases. Skin allergies first, then hay fever, then asthma, and then food allergies (Tan et al., 2011). Of course, it's never too late to change lifestyle, but a lot of suffering can be avoided if the first cue signal is understood by parents. In alternative medicine, the idea has already arisen that atopic diseases can be cured by changing diet (Farshchi et al., 2017). This hypothesis has also been proved by people following the Paleolithic diet: all sorts of atopic diseases have improved or been eliminated because this diet removes the nutrients which make the gut wall permeable (Szendi, 2011).

 

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