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Wilkey, O.B.

White matter integrity and processing speed in sickle cell anaemia - 2018

NMUH Staff Publications

<h4><span style="font-size: 10pt;">OBJECTIVE: <span style="font-size: 10pt;"><span style="font-weight: normal;">The purpose of this retrospective cross-sectional study was to investigate whether changes in white matter integrity are related to slower processing speed in sickle cell anemia.</span></span></span></h4><h4><span style="font-size: 10pt;">METHODS: <span style="font-size: 10pt;"><span style="font-weight: normal;">Thirty-seven patients with silent cerebral infarction, 46 patients with normal MRI, and 32 sibling controls (age range 8-37 years) underwent cognitive assessment using the Wechsler scales and 3-tesla MRI. Tract-based spatial statistics analyses of diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) parameters were performed.</span></span></span></h4><h4><span style="font-size: 10pt;">RESULTS: <span style="font-size: 10pt;"><span style="font-weight: normal;">Processing speed index (PSI) was lower in patients than controls by 9.34 points (95% confidence interval: 4.635-14.855, <em>p</em> = 0.0003). Full Scale IQ was lower by 4.14 scaled points (95% confidence interval: -1.066 to 9.551, <em>p</em> = 0.1), but this difference was abolished when PSI was included as a covariate (<em>p</em> = 0.18). There were no differences in cognition between patients with and without silent cerebral infarction, and both groups had lower PSI than controls (both <em>p</em> &lt; 0.001). In patients, arterial oxygen content, socioeconomic status, age, and male sex were identified as predictors of PSI, and correlations were found between PSI and DTI scalars (fractional anisotropy <em>r</em> = 0.614, <em>p</em> &lt; 0.00001; <em>r</em> = -0.457, <em>p</em> &lt; 0.00001; mean diffusivity <em>r</em> = -0.341, <em>p</em> = 0.0016; radial diffusivity <em>r</em> = -0.457, <em>p</em> &lt; 0.00001) and NODDI parameters (intracellular volume fraction <em>r</em> = 0.364, <em>p</em> = 0.0007) in widespread regions.</span></span></span></h4><h4><span style="font-size: 10pt;">CONCLUSION: <span style="font-size: 10pt;"><span style="font-weight: normal;">Our results extend previous reports of impairment that is independent of presence of infarction and may worsen with age. We identify processing speed as a vulnerable domain, with deficits potentially mediating difficulties across other domains, and provide evidence that reduced processing speed is related to the integrity of normal-appearing white matter using microstructure parameters from DTI and NODDI.</span></span></span></h4>&nbsp;