Dyslexia and familial high blood pressure: an observational pilot study.

BACKGROUND Developmental dyslexia is a neurodevelopmental learning disability characterised by unexpectedly poor reading and unknown aetiology. One hypothesis proposes excessive platelet activating factor, a potent vasodilator, as a contributor, implying that there should be a negative association between dyslexia and high blood pressure (HBP). Since both conditions have a partial genetic basis, this association may be apparent at the familial level. AIMS To test this prediction in dyslexic and non-dyslexic children. METHODS Individuals and families with (HBP+) and without (HBP-) a family history of HBP were compared. RESULTS Proportionately fewer dyslexics (49/112) than controls (11/12) were HBP+. Families with multiple, all dyslexic children were less likely to be HBP+ (7/16) than those with a non-dyslexic child (11/11). Within families, mean child scores on reading were higher in the HBP+ group (mean 44.3, SE 0.95) than in the HBP- group (mean 40.3, SE 0.87). CONCLUSION HBP+ family history is associated with better performance on reading. The prediction of a negative association between dyslexic status and familial high blood pressure is therefore confirmed.