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Physiological correlates of intellectual function in children with sickle cell disease: hypoxaemia, hyperaemia and brain infarction
Author(s) -
Hogan Alexandra M.,
Pitten Cate Ineke M.,
VarghaKhadem Faraneh,
Prengler Mara,
Kirkham Fenella J.
Publication year - 2006
Publication title -
developmental science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.801
H-Index - 127
eISSN - 1467-7687
pISSN - 1363-755X
DOI - 10.1111/j.1467-7687.2006.00503.x
Subject(s) - psychology , cerebral blood flow , pathophysiology , intelligence quotient , borderline intellectual functioning , hypoxia (environmental) , glymphatic system , cardiology , neuroscience , cognition , medicine , oxygen , cerebrospinal fluid , chemistry , organic chemistry
Lowered intelligence relative to controls is evident by mid‐childhood in children with sickle cell disease. There is consensus that brain infarct contributes to this deficit, but the subtle lowering of IQ in children with normal MRI scans might be accounted for by chronic systemic complications leading to insufficient oxygen delivery to the brain. We investigated the relationship between daytime oxyhaemoglobin saturation (SpO2), cerebral blood flow velocity (CBFV) and intellectual function (IQ) using path‐analysis in 30 adolescents with sickle cell disease (mean age 17.4 years, SD 4.2). Initial analyses revealed that the association between SpO2and Full Scale IQ (FSIQ) was fully mediated by increased CBFV, whereby SpO2was negatively correlated with CBFV and CBFV was negatively correlated with FSIQ, i.e. decreases in oxygen saturation are associated with increases in velocity, and increased velocity is associated with lowered IQ scores. The mediated relationship suggests that lowered IQ may be a function of abnormal oxygen delivery to the brain. Further analyses showed that the association between CBFV and IQ was significant for verbal but not for performance IQ. The pathophysiology characteristic of SCD can interfere with brain function and constrain intellectual development, even in the absence of an infarct. This supports the hypothesis that lowered intellectual function is partly explained by chronic hypoxia, and has wider implications for our understanding of SCD pathophysiology.