Presence of cerebral microbleeds is associated with worse executive function in pediatric brain tumor survivors

Background. A specific form of small-vessel vasculopathy-cerebral microbleeds (CMBs)-has been linked to various types of dementia in adults. We assessed the incidence of CMBs and their association with neurocognitive function in pediatric brain tumor survivors. Methods. In a multi-institutional cohort of 149 pediatric brain tumor patients who received cranial radiation therapy (CRT) between 1987 and 2014 at age <21 years and 16 patients who did not receive CRT, we determined the presence of CMBs on brain MRIs. Neurocognitive function was assessed using a computerized testing program (CogState). We used survival analysis to determine cumulative incidence of CMBs and Poisson regression to examine risk factors for CMBs. Linear regression models were used to assess effect of CMBs on neurocognitive function. Results. The cumulative incidence of CMBs was 48.8% (95% CI: 38.3-60.5) at 5 years. Children who had whole brain irradiation developed CMBs at a rate 4 times greater than those treated with focal irradiation (P <. 001). In multivariable analysis, children with CMBs performed worse on the Groton Maze Learning test (GML) compared with those without CMBs (Z-score-1.9; 95% CI:-2.7,-1.1; P <. 001), indicating worse executive function when CMBs are present. CMBs in the frontal lobe were associated with worse performance on the GML (Z-score-2.4; 95% CI:-2.9,-1.8; P <. 001). Presence of CMBs in the temporal lobes affected verbal memory (Z-score-2.0; 95% CI:-3.3,-0.7; P =. 005). Conclusion. CMBs are common and associated with neurocognitive dysfunction in pediatric brain tumor survivors treated with radiation.