Neuropsychologta, Vol. 25, No. 4, pp. 66S674. 1987. Printed in Great Britain.

0028-3932/87 53.0O+O.C~l 0 1987 Pergamon Journals Ltd

LEFT-HANDEDNESS: ITS ASSOCIATION WITH ALLERGIC DISEASE

JOCELYN SMITH*

University of York, Department of Psychology, Heslington, York YOl SDD, U.K

(Received 1 September 1986; accepted 20 January 1987)

Abstract-It has been postulated that anomalous cerebral dominance is associated with disorders of the immune system and increased incidence ofautoimmune diseases has been reported in left-handed individuals. In this study, 313 patients attending an allergy clinic were assessed for left- and right- handedness, using the Edinburgh Handedness Inventory. The results were compared to those in 350 age- and sex-matched control individuals. It was found that significantly more (PC 0.02) left-handers than right-handers attended the clinic. Among atopic patients in general, patients with IgE-mediated symptoms, patients with urticaria and patients with eczema, there was a highly significant increase in left-handers (P<O.O05). The results are discussed in terms of Geschwind’s theory of cerebral dominance.

INTRODUCTION

IN THE past, left-handedness has been accepted as a sign of backwardness and clumsiness, and as a generally undesirable attribute. More recently, sinistrality has been shown to occur together with childhood learning disorders [6] as well as with more desirable attributes such as sporting ability [ll], artistic skill [14, 161 and mathematical ability [lo]. Recently immune disorders have been linked to left-handedness, notably autoimmune disease such as myasthenia gravis [6, 71. It is also well documented that left-handedness is more common in males than in females [ 151 and this difference is presumably due to constitutional, as opposed to postnatal, environmental factors.

These seemingly diverse characteristics have been incorporated into a theory of left- handedness by GESCHWIND and BEHAN [3,4,6, 7, 10, 131. They proposed that some male factor, present in utero, influences cerebral organisation in a way which results in the anomalous dominance found in some left-handers. Geschwind defined anomalous dominance as the pattern of cerebral organisation which deviates in any way from that of “standard dominance” found in the majority of right-handers, in which the left hemisphere is lateralized for language functions and the control of the preferred hand, while the right hemisphere is dominant for visuo-spatial functions [3]. The male factor he proposed is the hormone testosterone, produced by the male foetus once the testes have formed and, to a lesser degree, by the mother’s ovaries and placenta, and he suggested that this hormone exerted its effect by slowing down development of the left hemisphere, especially in the regions associated with language functions, i.e., the superior temporal region, and with handedness. Since the male foetus is exposed to more testosterone than a female foetus, on

*Address for correspondence: University of Cambridge, Department of Experimental Psychology, Downing Street, Cambridge CB2 3EB, U.K.

665

666 JOCELYN SMITH

average the effect of the hormone will be greater in utero for the former than for the latter and this would account for the observed elevated rate of sinistrality in males.

Geschwind also suggested that if this delaying process was very marked it would lead to particular cortical abnormalities such as those found by GALABURDA and KEMPER [2] in the brain of a childhood dyslexic, and hence Geschwind’s theory accounts for the increased frequency of dyslexia in boys. The increased rate of left-handedness amongst twins [ 181, disputed, however, by MCMANUS [12], can also be expiained by Geschwind’s theory, since it may be assumed that twins are exposed to twice the level of testosterone in ufero as a singleton is, and hence would be more likely to develop anomalous cerebral dominance.

Geschwind proposed that other systems might be affected by the same delaying process in males, i.e. increased testosterone levels in utero could also retard the maturation of the immune system: suppression of foetal thymic growth would then interfere with the sclf- recognition process which occurs in foetal lift and lead to an increased incidence of autoimmune disorders in childhood and adulthood. He cited evidence in support of such a testosterone effect [.5, 81.

In man, immune disorder can be expressed in several ways. First, as outlined above, the lymphocytes can mount an attack on the body’s own cells, resulting in autoallergy or autoimmunity and diseases such as Hashimoto’s thyroiditis, ulcerative colitis and myasthenia gravis. GESCHWINI) and BEHAN 16. 71 found a significantly higher incidence of left-handedness among individuals suffering from such autoimmune disorders than among controls and, conversely, a significantly higher incidence of these diseases among left- handers than among right-handers.

Immune disorders can also appear when defensive reactions occur to non-invading harmless substances, i.e. allergens, which in certain people elicit the formation of specific antibodies, immunoglobulin E (IgE) antibodies 191. Interaction of IgE-antibodies and allergens on the surface of mast cells triggers the release of substances, including histamine, which produce the symptoms of allergy, notably skin rash, itching, sneezing and breathing difficulties, due to vasodilation, increased fluid secretions and muscle contraction. This second mechanism of immune disorder underlies common allergies such as eczema, asthma and rhinitis. Although GESCHWIND [3,4] briefly discussed this aspect of immune disorder he investigated the possible relationship between left-handedness and immune disorder only in terms of autoimmune disease, and did not repeat his study among allergic individuals.

It is precisely this extension of Geschwind’s research that the present study sets out to perform: that is, to investigate whether or not there is an increased rate of left-handedness among individuals suffering from allergy.

The allergies to be considered include eczema, asthma, urticaria, food- and insect sting- allergies. The first three of these are associated with high titres of IgE-antibodies and may thus reflect severe disturbance in immunological function. An atopic individual is one who produces IgE-antibodies in an allergic response when the appropriate allergen is introduced to the skin. Approximately one-third of the general population is believed to be atopic. yet of these individuals only one-third (i.e. 1 1 “%I of the general population) will actually suffer from symptoms of allergic disease. Two-thirds of atopic individuals may therefore be unaware of their immune disorder. since it remains unexpressed. If, as Geschwind proposed, there is an association between left-handedness and immune disorder. there should be an increased incidence of sinistrality among persons selected for showing atopy, compared to the general population. The results in a group of 313 such patients attending an allergy clinic arc reported here.

LEFT-HANDEDNESS: ITS ASSOCIATION WITH ALLERGIC DISEASE 667

METHOD Subjects

The experimental group consisted of 313 patients, 147 males and i66 females, attending the allergy clinic at St Mary’s Hospital, London, over a 4-week period. These patients were not all residents of London, and many in fact had travelled from different parts of England to attend the clinic. The control group consisted of 350 individuals, 164 males and 186 females, matched for age and sex with the experimental group. These individuals were selected at random from Paddington and King’s Cross railway stations and were presumed to be representative of the general population of England. Members of this control group were from different parts of England and of a mixed social class and educational background and profession, and thus served as an appropriate control with which to compare the experimental group. These control individuals were given the Handedness Inventories to complete while they were waiting in the railway stations, and the Inventories were collected a few minutes later. Their participation was entirely voluntary, and no payment or any other inducement was offered.

Assessment of handedness

The questionnaires were given to subjects in the clinic, and to the control group at the stations. To assess the handedness of the subjects in the experiment, a modified version of the Edinburgh Handedness Inventory was used. The handedness ofeach individual was assessed by a battery of questions and a score, called the Laterality Quotient (LQ), was then derived for each subject. The LQ can range from ~ 100 (extreme left-handedness) to + 100 (extreme right-handedness) and allows the intermediate degrees of left- and right-handedness to be taken into account, in contrast to a simple self-report technique. The criterion of LQ <O was taken to indicate left-handedness in the following experiment, in accordance with OLDFIELD [15].

Procedure

The handedness of each patient attending the clinic was assessed as described above. In the clinic, routine skin tests were carried out on every patient to determine whether or not he or she was atopic (produced a positive skin test to one or more of the allergens under test). The skin test consisted of pricking the superficial skin layer so as to allow a small amount of allergen solution to enter, the solutions under test being: grass pollen, house dust, house dust mites. cat hair, various types offungal spore, certain foods, and histamine. A positive response, indicating atopy. was defined as a weal exceeding 2 mm in diameter. A smaller weal was taken as an indication that the patient was non- atopic. Further information concerning each patient was provided by a doctor as to whether the patient’s symptoms were believed to be IgE-mediated (allergic) or non-IgE-mediated (non-allergic), based on the patient’s clinical history backed up by the results of tests for specific IgE antibodies to the allergens suggested by the clinical history. Each patient was seen by one of thirteen doctors at the clinic over the 4-week period and each of these doctors was ignorant of the patient’s LQ score on the Handedness Inventory.

Thus, for the experimental group. medical diagnoses were obtained so that information was available about whether a given patient was atopic or non-atopic (whether he or she produced IgE-antibodies in reaction to common allergens) and whether the symptoms were IgE-mediated or non-IgE-mediated (whether the condition was allergic or non-allergic). The incidence of left-handedness among patients with immune disorders, atopic patients, and the subset of this latter group who were diagnosed as having IgE-mediated symptoms, was noted.

The chi-squared test was used for all statistical calculations, unless otherwise indicated, with one degree of freedom.

RESULTS

The distribution of Laterality Quotient in the control group is shown in Table 1. The observed frequencies of left-handedness are much in line with those reported in other studies [15].

The distribution of Laterality Quotient for control subjects and allergy patients is shown in Fig. 1 for both sexes together. The proportions of males and females in both the control group and the total patient group were very similar (47% males, 53% females). From Fig. 1, it can be seen that there is an excess of allergy patients with LQ < 0, especially in the range of -40 to 0.

However, of this patient group of 313 subjects, 36 were excluded from further study because their diagnoses were not obtained from a doctor at the clinic. This group of 36 consisted of 17 females (none with LQ ~0, 17 with LQ > 0) and 19 males (2 with LQ < 0,

668 JOCELYN SMITH

Table 1. The distribution of Laterality Quotient among control subjects

LQ<O LQ>O % left-handers

Males 18 146 10.98 Females 13 173 6.99

31 319 8.86

100

2 M

n’

3 7310

$ E 2

0 100

LEFT

-50 0 +%I +lOO Latemllty Quotient RIGHT

FIG. 1. The distribution of Laterality Quotient in allergy patients and control subjects.

17 with LQ>O). The distribution of Laterality Quotient in the remaining group of 277 patients was as shown in Table 2.

The rate of left-handedness in male patients was higher than that for female patients, and also 1.6 times higher than the corresponding rate for male control subjects, although this difference was not significant (x2 = 1.85, d.f. = 1, P> 0.10). The rate of left-handedness in female patients was 2.2 times greater than the corresponding rate in female control subjects, and this difference was significant (x2 = 5.31, d.f. = 1, P-c 0.05).

The failure to find significance in the data for male subjects could be attributable, at least in part, to the fact that there were fewer male subjects than female subjects, and it is necessary to have a large number of subjects to obtain sufficient left-handers within the sample. In view of this fact, the data from the two sexes were pooled, and in so doing, the proportions of males and females in the allergic group were maintained as being the same as in the original group before exclusion of the 36 patients, i.e. the same proportions as in the control group (47% males, 53% females).

The remaining results, therefore, are presented as pooled data, and for each comparison made between the allergic patients and controls, the male: female ratio remained approximately constant, so justifying the pooling of data from the two sexes to obtain a larger sample.

The number of left-handers in certain categories of patients is shown in Table 3. There were thus 3 13 patients attending the clinic, and among this group there were 47 (15.02%) left- handers. There was a significant difference between the rates of left-handedness in this overall patient group and in the control group (x2 = 5.46, d.f. = 1, Pt0.02). Following the exclusion of the 36 patients as described previously, the remaining group of 277 patients consisted of

LEFT-HANDEDNESS: ITS ASSOCIATION WITH ALLERGIC DISEASE 669

Table 2. The distribution of Laterality Quotient among the final group of allergy patients

LQiO LQ>O % left-handers

Males 22 106 17.19 Females 23 126 15.44

45 232 16.25

Table 3. The incidence of left-handedness in certain categories of allergy patients

Category Total Number of % of total

number left-handers left-handed

Control All attending clinic All attending clinic after exclusion of those without

diagnosis Atopic Non-atopic IgE-mediated disease Non-IgE-mediated disease IgE-mediated rhinitis Non-IgE-mediated rhinitis IgE-mediated eczema Non-IgE-mediated eczema IgE-mediated asthma Non-IgE-mediated asthma IgE-mediated rhinitis/asthma/eczema Non-IgE-mediated rhinitis/asthma/eczema Urticaria IgE-mediated urticaria Non-IgE-mediated urticaria

350 31 8.86 313 47 15.02

277 45 16.25 218 39 17.89

59 6 10.17 199 37 18.59

78 8 10.26 145 23 15.86

18 1 5.56 32 9 28.13

2 0 0.00 103 15 14.56

8 1 12.50 182 30 16.48 25 2 8.00 48 12 25.00 22 8 36.36 26 4 15.38

1.8 times as many left-handers relative to the control group, and this difference was significant (x2=7.25, d.f.= 1, P<O.Ol).

Since interest is to be focused on the rate of sinistrality among individuals with immune disorder, the experimental group of 277 patients was subdivided on the basis of the skin-test results. This yielded 218 atopic (positive skin test) and 59 non-atopic (negative skin test) patients, and the incidence of left-handedness was 1.8 times as great in the former as in the latter. This difference was not significant (x2 = 1.51, d.f. = 1, P>O.lO), but when the atopic group were compared with the controls there were significantly more left-handers in the atopic group (x2 = 9.32, d.f. = 1, P<O.O05).

Since some atopic patients do not necessarily develop IgE-mediated symptoms as a result of their immune disorder (see Discussion), and because some patients were attending the clinic for symptoms with a non-allergic (non-IgE-mediated) cause, it seemed useful to subdivide patients further according to whether their symptoms were IgE-mediated (and hence whether they showed true immune disorder) or non-IgE-mediated. This gave 199 patients with IgE-mediated symptoms and 78 with non-IgE-mediated symptoms. Although the rate of left-handedness was 1.8 times as great in the former as in the latter, this result was not significant (x2 =2.28, d.f.= 1, P>O.lO). However, the rate of left-handedness was 2.1

670 JOCELYN SMITH

times as great in the allergic patients as in the controls, and this result was highly significant (x2= 10.20, d.f.= 1, P<O.O05).

As the allergic forms of rhinitis, asthma and eczema are associated with the highest serum levels of IgE-antibodies, it was thought interesting to discover the rate of left-handedness among patients with these IgE-mediated conditions. Often two of these three diseases occur together, sometimes all three together, so that the data were pooled and each patient was scored only once even if he or she suffered from more than one illness. This pooling of data gave 182 allergic, and 25 non-allergic patients. Comparison of the rates of left-handedness between the (pooled) rhinitis, asthma and eczema patients and control subjects showed a significant difference (x2 = 6.13, d.f. = 1, P-c 0.02), there being 1.9 times as many left-handers in the pooled group as in the controls. Although the incidence of left-handers among the 182 allergic patients was 2.1 times greater than among the 25 non-allergic patients, this difference was not significant (x2 =0.65, d.f. = 1, P>O.lO), presumably because of the small numbers involved.

When patients diagnosed as suffering from rhinitis, asthma and eczema were considered in their separate disease categories (although it must be remembered that some individuals in one of these categories will also be included in one or other or both ofthe other two categories because of the non-independence of these diseases), there were 163 patients diagnosed as suffering from rhinitis, 34 from eczema and 111 from asthma. Of the patients with rhinitis, the symptoms of 145 were IgE-mediated and of 18 were non-IgE-mediated. The difference between the rates of left-handedness in these two subgroups of rhinitis patients was not significant (1’ = 0.66, d.f. = 1, P> 0. lo), although the incidence of sinistrality in the allergic rhinitis sufferers was 2.9 times as great as in the subgroup of non-allergic patients. However, comparison between the allergic rhinitis patients and controls revealed a significant difference (x2 = 4.48, d.f. = 1. P-c 0.05). there being more left-handers in the former than in the latter.

There were 103 patients diagnosed as suffering from allergic asthma and 8 with non- allergic asthma. The difference in rates of left-handedness in these two subgroups of asthma patients was not significant (x2 =0.13, d.f. = 1, P>O.lO), as was the difference between IgE-mediated asthma patients and the controls (x2 = 2.25, d.f. = I, P > 0. lo), although for both of these comparisons a higher incidence of left-handedness was found in the allergic patients than among controls or non-allergic asthma patients.

Among the 34 eczema patients there were 32 with IgE-mediated symptoms and only 2 with non-IgE-mediated symptoms. The incidence of left-handedness amongst the allergic patients was significantly higher than among controls (x2 =9.65, d.f. = 1, P<O.O05), but not significantly higher than amongst the non-allergic eczema group (Fisher’s Exact Probabi- lity =0.53).

The incidence of left-handedness among the 48 patients with urticaria was significantly higher than amongst controls (x2 = 9.80, d.f. = 1, P-c O.OOS), and when these patients were subdivided on the basis of whether their symptoms were IgE-mediated or not, it was found that there were significantly more left-handers among the IgE-mediated urticaria patients than among controls (x2= 13.89, d.f.= 1, P<O.OOl).

However, comparison between these patients and those with non-IgE-mediated urticaria showed no significant difference with respect to left-handedness (x2 = 1.79, d.f. = 1, P > O.lO), although the incidence of sinistrality was higher among the allergic patients. The incidence of left-handedness was surprisingly high among the patients with non-IgE-mediated urticaria (15.38%) although not significantly higher than among controls (x2 =0.57, d.f.= 1,

LEFT-HANDEDNESS: ITS ASSOCIATION WITH ALLERGIC DISEASE 671

P>O.lO). This increased rate among non-allergic individuals may explain, in part at least, the finding that no significant difference appeared to exist between IgE-mediated and non- IgE-mediated urticaria patients.

In the light of this somewhat unexpected finding for urticaria it was felt necessary to exclude from this sample of patients any whose conditions were known to be accompanied by any other disease, such as rhinitis, asthma or eczema. Thus a sample of “pure” urticaria patients was obtained in order to see whether the same pattern of results would emerge as that for the urticaria patients discussed above.

Table 4. The incidence of left-handedness in “pure” urticaria patients

Category Total Number of

number left-handers % of total left-handed

All with urticaria 33 8 24.24 IgE-mediated urticaria 10 5 50.00 Non-IgE-mediated urticaria 23 3 13.04

As shown in Table 4, this second analysis showed an even higher incidence among those with IgE-mediated urticaria whilst it reduced the incidence among those with non-IgE- mediated urticaria. Thus, there were significantly more left-handers among patients with IgE-mediated urticaria than among (a) controls (x2 = 14.00, d.f. = 1, P<O.OOl), and (b) non-IgE-mediated urticaria patients (Fishers’s Exact Probability = 0.04). The incidence of left-handedness among all 33 urticaria patients was also significantly higher than among controls (x2 =6.21, d.f. = 1, P<O.O2).

Other diagnoses included insect-sting allergy (4 patients) and food-allergy/intolerance (11 patients), but because of the small numbers involved these patients were not included in the analysis-by-disease, but were included in the analysis of atopic/non-atopic and IgE- mediated/non-IgE-mediated patients.

DISCUSSION

The results of this experiment show clearly that an increased rate of left-handedness was found in many of the categories of allergic disease considered (rhinitis, asthma, eczema and urticaria), and that the overall pattern of results is in agreement with the hypothesis under test. Thus, there is a significantly greater incidence of left-handedness among all the patients attending the clinic over the 4-week period than in the general population controls, and this increases still further after exclusion of some patients, both left- and right-handers, on the grounds that their diagnoses were not available. Since 33% of the general population, and hence of the control group, are believed to be atopic, the significant increase of left- handedness among the group of atopic patients over and above that of the controls is extremely interesting and seems to provide powerful support for the hypothesis.

The above result is, however, hard to reconcile with the seemingly contradictory finding that there was no significant difference between the incidences of left-handedness among atopic and non-atopic patients, the former of which are assumed to show immune disorder while the latter are assumed to show no such abnormalities (as opposed to the control group,

who were assumed to consist of some atopic individuals, if not as many as 33%). The incidence of left-handedness was certainly higher in the atopic group than in the non-atopic group, and the failure of the difference to reach significance can be attributed perhaps to the relatively small number of subjects. In order that an incidence of left-handedness of 17.89% among 218 atopic individuals should be significantly greater than the rate of 10.17% among non-atopic patients, there would need to be more than 170 individuals in this latter group. But because subjects were not selected for atopy or non-atopy and simply consisted of individuals attending the allergy clinic over a certain period of time, the group sizes could not be controlled, and unfortunately only 59 non-atopic patients were available.

The significantly larger incidence of left-handedness in patients diagnosed as suffering from IgE-mediated (allergic) disease compared to the controls is strong support for the hypothesis, since the latter group will consist of some individuals (approx 1 I %) who would suffer from IgE-mediated disease. as was noted earlier. It is also interesting that of the 218 atopic patients (17.89’!/0 of whom were left-handed) immune disorder was expressed as IgE- mediated disease in 199 patients (18.59% of whom were left-handed), and, thus, a higher incidence of sinistrality was found among this latter group with severe immunological disturbance. There does not, however, seem to be a clear explanation for the finding that the increased incidence of sinistrality in patients with IgE-mediated disease compared with those not so mediated. fails to reach significance. Again, perhaps the paucity ofnumbers in the non- allergic group could account for this, as outlined above for the atopic and non-atopic pattern. The direction of the results for allergic and non-allergic patients is clearly in support of the hypothesis.

Further support is provided by the data from patients suRering from rhinitis. asthma and eczema. As stated earlier. these conditions arise from the highest serum levels of IgE- antibodies, and the results of the experiment show significantly higher incidences of sinistrality in the groups of patients with IgE-mediated rhinitis and eczema compared with the control group. and in groups of patients pooled for IgE-mediated rhinitis. asthma and eczema. It is not clear why the difference in occurrence of left-handedness between the allergic asthma patients and the controls fails to reach significance. It is extremely interesting to find such a high rate of left-handers (28.13%) among patients with allergic eczema, since this condition is believed to result from the highest-known serum levels of IgE-antibodies, and thus the hypothesis under test would predict the highest incidence of left-handedness among these individuals.

The highest rate of sinistrality was found among patients suflering from urticaria, whether from this condition alone or accompanied by other symptoms. This is a little-understood condition which is thought to have several possible causes [I]. It is possible that the particular allergen to which the urticaria patient will react is not included among the skin- test solutions and hence the test will fail to assess the true diagnosis concerning atopy for that patient. This is unlikely, however, since the skin-testing procedure includes as many known allergens as possible. The urticaria may be due to some other kind ofimmunological disorder not mediated by IgE-antibodies and thus the simple dichotomy between IgE-mediated and non-IgE-mediated urticaria may be inappropriate.

It would be interesting to extend the findings presented here to provide further support for Geschwind’s theory, such as studying the incidence of sinistrality among other kinds of immunological disorders. One such disorder that might be of importance is anaphylaxis, a condition of extreme allergic shock. Since this is such a severe reaction, it would be interesting to discover whether the incidence of left-handedness is increased in such

LEFT-HANDEDNESS: ITS ASSOCIATION WITH ALLERGIC DISEASE 613

individuals. One could also investigate whether there is any relationship between left- handedness and allergy in first- and second-degree relatives of individuals showing immune disorder, since the allergic diseases included in this study, at least, are believed to occur within families and to be passed on from one generation to the next, and it is generally accepted that left-handedness has at least some genetic component (the probability of two left-handed parents producing a left-handed child is approximately 0.46, compared with 0.02 if both parents are right-handed, and 0.17 if only one parent is left-handed [17]).

The study reported here was carried out to validate the hypothesis that patterns of cerebral dominance are associated with disorders of the immune system [.5,6,7]. Development of the normal brain is asymmetrical with sulcation occurring first on the right side: growth of the left hemisphere is delayed compared to that of the right. When the delay is more severe than normal, the right hemisphere is “favoured” and makes more synaptic connections to both sides: anomalous dominance occurs. If left-sided growth is severely retarded, anatomical evidence of abnormal neuronal migration can be found, as reported in dyslexics [2]. It has been postulated [3,4, 5,6, 7, lo] that it is increased testosterone which may cause delayed maturation of the brain, resulting in neurodevelopmental abnormalities, and also affecting the immune system so as to cause an increased predisposition to immunological diseases in both child- and adulthood. An increased incidence of autoimmune disorders has already been associated with left-handedness [6, 193 and the work carried out here shows that an increased incidence of allergic diseases is also present.

If Geschwind’s theory of the development of left-handedness is correct, it could be that it is not the predisposition to allergic disease itself which is inherited, as has been assumed in the past, but rather the exaggerated testosterone levels in utero, or the enhanced foetal sensitivity to testosterone, which runs in families, and which is expressed as allergic disease and left- handedness after birth. The very fact that not all left-handers suffer from immune disorders, and that many right-handers do suffer from such disorders, is evidence that any model proposed to account for the significant association found here between sinistrality and allergic disease and between sinistrality and autoimmune disease, as found by GESCHWIND

and BEHAN [6,7] must be far from simplistic. Indeed, there seems to be some support for the notion that there are two types of sinistrality: that in which a familial history of left- handedness can be traced, and that in which no such familial history can be traced. Thus, these two types of left-handedness may be correlated with different courses of development of the foetal immune system and may account, at least in part, for the discontinuity in the relationship between immune disorder and the broad concept of left-handedness.

Acknowledgements-This research was undertaken as an undergraduate project for a B.Sc. Psychology at the University of York, England. I am very grateful to Dr. P. Ewan, Department of Immunology, St. Mary’s Hospital, London, for granting access to patients attending the allergy clinic, and for her help and advice. I am also very grateful to Dr. P. Behan, Institute of Neurological Science, Southern Genera1 Hospital, Glasgow, for his encouragement and advice during this research, and to Dr. E. Macphail, University of York, for his help and enthusiasm throughout.

REFERENCES

1. DENMAN, A. M., PLATTS-MILLS, T., BRERETON, P. J., DODDYMEAD, L., SOAN, R., PELTON, B. K., LOEWI, G., SHINER, M. and PETERS, D. K. Urticaria and dietary hypersensitivity. In Antigen Absorption by the Gut, W. A. HEMMINGS (Editor), pp. 167-181. MTP Press Limited, 1978.

2. GALABURDA, A. M. and KEMPER, T. L. Cytoarchitectonic abnormalities in developmental dyslexia. Ann. Neural. 6, 94, 1979.

3. GESCHWIND, N. The biology of cerebra1 dominance: Implications for cognition. Cognition 17, 193 -208, 1984.

614 JOCELYN SMITH

4. 5.

6.

7.

8. 9.

10. 11.

12.

13. 14.

15.

16.

17.

18.

19.

GESCHWIND, N. Cerebral dominance in biological perspective. Neuropsychologin 22, 675-683, 1984. GESCHWIND, N. Immunological associations of cerebral dominance. In Neuroimmunoloyy, P. BEHAN and F. SPREAFICO (Editors), pp. 451461. Raven Press, New York, 1984. GESCHWIND, N. and BEHAN, P. Left-handedness: Association with immune disease, migraine, and developmental learning disorder. Proc. nntn. Acad. Sci. U.S.A. 79, 5097T5100, 1982. GESCHWIND, N. and BEHAN, P. Laterality, hormones and immunity. In Cerebral Dominance, N. GESCHWIN~ and A. GALABUKDA (Editors), pp. 211-224. Harvard University Press, 1984. HOOD, L. E., WEISMAN, I. L., WOOD, W. B. and WILSON, J. K. Immunology, p. 258. Benjamin/Cummings, 1984. KNOX, R. B. Pollen and Allergy, pp. 49-57. Studies in Biology, 107, Arnold, 1979. KOLATA, G. Math genius may have hormonal basis. Science 222, 1312, 1983. MCLEAN, J. M. and CIURCZAK, F. M. Bimanual dexterity in major league baseball players: A statistical study. New Engl. J. Medicine 2, 1278 1279, 1982. MCMANUS, I. C. Handedness, language dominance and aphasia: A genetic model. Psychologicu1 Medicine (Monograph Supplement 8), 1985. MARX, J. L. Autoimmunity in left-handers. Science 217, 141-144, 1982. MEBERT, C. J. and MICHEL, G. F. Handedness in artists. In Neuropsychology of‘Lt$-Handrdness, J. HERRON (Editor), pp. 273~ 279. Academic Press, 1980. OLDFIELU, R. C. The assessment and analysis of handedness: The Edinburgh Inventory. Nruropsycllologia 9, 97~_113, 1971. PETERSON, J. M. and LANSKY, L. M. Left-handedness among architects: Some facts and speculations. Percrpl. Mot. Skills 38, 547-550, 1972. SPRINC;ER. S. P. and DEIJTSCH, G. Ltiff Bruin, Right &an, pp. 107-109. W. H. Freeman & Co., San Francisco, 1981. SPRIXER. S. P. and SIARLEMAX. A. Left-handedness in twins: Implications for the mechanisms underlying cerebral asymmetry of function. In Nruropsychology of‘ Lcfi-Handedness, J. HERROP; (Editor). pp. 139 158. Academic Press, 1980. Woor), L. Premature grey hair, “mixed” cerebral dominance, and other characteristics of developmental dyslexia in patients with various thyroid disorders and in control patients having health check-ups. Ah.srruc,rs, American Tllyroid Association, New Orleans, 1983.