Dyslexia, left-handedness, and immune disorders
F. E. Tonnessen, A. Lokken, T. Hoien and I. Lundberg
Center for Reading Research, Stavanger, Norway.
OBJECTIVE--To illuminate a possible three-way association between dyslexia,
immune disorders, and left-handedness. Geschwind's, Behan's, and
Galaburda's hypotheses have been of special interest in this connection.
DESIGN--Statistical analysis based on general assessment of the prevalence
of the three aforementioned conditions. PARTICIPANTS--There were 734
children included from a total of 1165 in grade 6 (about 12 years of age)
in the municipality of Stavanger, Norway. SETTING--Educational and
demographic statistics indicate that the municipality of Stavanger is
representative of the national population at large regarding the three
conditions examined. MAIN OUTCOME MEASURES--A screening test with high
reliability and validity was used to assess reading ability. It measured
word recognition and phonological decoding. The questionnaires that
recorded the students' handedness and immune disorders were filled in by
the parents. Handedness was assessed by a Norwegian version of the Oldfield
Inventory. A questionnaire concerning allergies and asthma was used to
assess the prevalence of immune disorders. RESULTS--The bivariate analyses
disclosed a significant association between handedness and dyslexia and a
significant but weak association between handedness and immune disorders.
No significant association was found between dyslexia and immune disorders.
A triadic analysis yielded the following: 66.7% of the left-handed dyslexic
children had immune disorders (P > .05); 42.1% of the left-handed
children with immune disorders had dyslexia (P < .01); and 32% of the
dyslexic children with immune disorders were left-handed (P < .05).
CONCLUSIONS--There seems to be some association between dyslexia,
left-handedness, and immune disorders. Of the three factors, handedness
seems to be the most important association. The findings lend some support
to the one interpretation of the hypotheses of Geschwind, Behan, and
Galaburda.
