Characterization of brain development with neuroimaging in a female mouse model of chemotherapy treatment of acute lymphoblastic leukemia.

Background: Survivors of pediatric acute lymphoblastic leukemia (ALL) exhibit abnormal neurocognitive outcomes that are possibly due to exposures to neurotoxic chemotherapy agents. This study aimed to determine the feasibility of characterizing long-term neuroanatomical changes with in vivo neuroimaging in a preclinical model of treatment for ALL. Methods: Female mice (C57BL/6) were randomly assigned to a saline control group (n=10) or a treatment group (n=10) that received intrathecal methotrexate and oral dexamethasone (IT-MTX + DEX). Mice were subsequently scanned three times on a 7T MRI at ages 3, 6, and 12 months (T1, T2, and T3, respectively), which corresponds with human age-equivalents spanning early to late adulthood. Regional brain volumes were automatically segmented, and volume change between timepoints (i.e., T1 to T2; and T2 to T3) were compared between groups (i.e., saline vs. IT-MTX + DEX). Results: Five mice in the IT-MTX + DEX group, and seven mice in the saline group completed all three scans. Between T1 and T2, volumetric change was significantly different between groups in total gray matter [estimate =2.06, 95% confidence interval (CI): 0.27-3.84], the cerebrum (estimate =1.62, 95% CI: 0.14-3.09), claustrum (estimate =0.06, 95% CI: 0.02-0.09), amygdala (estimate =0.16, 95% CI: 0.03-0.29), and striatum (estimate =0.18, 95% CI: 0.01-0.35), with the IT-MTX + DEX group exhibiting a more robust increase in volume than the saline-treated group. Between T2 and T3, group differences in structural brain development were evident for total white matter (estimate =-0.14, 95% CI: -0.27 to -0.01), and the corpus callosum (estimate =-0.09, 95% CI: -0.19 to 0.00) and amygdala (estimate =-0.05, 95% CI: -0.10 to 0.00). In contrast to the rapid brain growth observed earlier in development (i.e., T1 to T2), the IT-MTX + DEX group exhibited an attenuated increase in volume relative to the saline-treated group between T2 and T3. Conclusions: The results demonstrate feasibility of modeling pediatric ALL treatment in a preclinical model and highlight the potential of using preclinical neuroimaging models to gain insight into brain development throughout survivorship.

Neurocognitive and psychosocial outcomes in survivors of childhood leukemia with Down syndrome.

OBJECTIVE: The primary aim of this study was to assess the feasibility of a developmentally tailored neurocognitive assessment in survivors of childhood acute leukemia with Down syndrome (DS-leukemia). A secondary aim was to compare outcomes in the DS-leukemia group to a historical comparison group of individuals with DS and no history of childhood cancer. METHODS: Survivors of DS-leukemia (n = 43; 56% male, mean [SD] age at diagnosis = 4.3 [4.5] years; age at evaluation = 15 [7.9] years) completed a neurocognitive assessment battery that included direct measures of attention, executive function, and processing speed, and proxy ratings of attention problems and executive dysfunction. Direct assessment outcomes were compared to a historical comparison cohort of individuals with DS and no history of childhood cancer (DS-control; n = 117; 56% male, mean [SD] age at evaluation = 12.7 [3.4] years). RESULTS: Rates of valid task completion ranged from 54% to 95%, suggesting feasibility for most direct assessment measures. Compared to the DS-control group, the DS-leukemia group had significantly lower completion rates on measures of executive function (p = 0.008) and processing speed (p = 0.018) compared to the DS-control group. There were no other significant group differences in completion rates. Compared to the DS-control group, the DS-leukemia group had significantly more accurate performance on two measures of executive function (p = 0.032; p = 0.005). Compared to the DS-control group, the DS-leukemia group had significantly more problems with executive function as identified on proxy ratings (6.5% vs. 32.6%, p = <0.001). CONCLUSION: Children with Down syndrome (DS) are at increased risk for developing acute leukemia compared to the general population but are systematically excluded from neurocognitive outcome studies among leukemia survivors. This study demonstrated the feasibility of evaluating neurocognitive late effects in leukemia survivors with DS using novel measures appropriate for populations with intellectual developmental disorder.

Genetic variants, neurocognitive outcomes, and functional neuroimaging in survivors of childhood acute lymphoblastic leukemia.

BACKGROUND: Genetic predispositions may modulate risk for developing neurocognitive late effects in childhood acute lymphoblastic leukemia (ALL) survivors. METHODS: Long-term ALL survivors (n = 212; mean = 14.3 [SD = 4.77] years; 49% female) treated with chemotherapy completed neurocognitive testing and task-based functional neuroimaging. Based on previous work from our team, genetic variants related to the folate pathway, glucocorticoid regulation, drug metabolism, oxidative stress, and attention were included as predictors of neurocognitive performance, using multivariable models adjusted for age, race, and sex. Subsequent analyses evaluated the impact of these variants on task-based functional neuroimaging. Statistical tests were 2-sided. RESULTS: Survivors exhibited higher rates of impaired attention (20.8%), motor skills (42.2%), visuo-spatial memory (49.3%-58.3%), processing speed (20.1%), and executive function (24.3%-26.1%) relative to population norms (10%; P < .001). Genetic variants implicated in attention deficit phenotypes predicted impaired attention span (synaptosome associated protein 25, F(2,172) = 4.07, P = .019) and motor skills (monoamine oxidase A, F(2,125) = 5.25, P = .007). Visuo-spatial memory and processing speed varied as a function of genetic variants in the folate pathway (methylenetetrahydrofolate reductase [MTHFRrs1801133], F(2,165) = 3.48, P = .033; methylenetetrahydrofolate dehydrogenase 1 [MTHFD1rs2236225], F(2,135) = 3.8, P = .025; respectively). Executive function performance was modulated by genetic variants in the folate pathway (MTHFD1rs2236225, F(2,158) = 3.95, P = .021; MTHFD1rs1950902, F(2,154) = 5.55, P = .005) and glucocorticoid regulation (vitamin D receptor, F(2,158) = 3.29, P = .039; FKBP prolyl isomerase 5, F(2,154) = 5.6, P = .005). Additionally, MTHFD1rs2236225 and FKBP prolyl isomerase 5 were associated with altered brain function during attention and working memory (P < .05; family wise error corrected). CONCLUSIONS: Results extend previous findings of genetic risk of neurocognitive impairment following ALL therapy and highlight the importance of examining genetic modulators in relation to neurocognitive deficits.

Iron deficiency and internalizing symptom severity in unmedicated adolescents: a pilot study.

BACKGROUND: Iron plays a key role in a broad set of metabolic processes. Iron deficiency is the most common nutritional deficiency in the world, but its neuropsychiatric implications in adolescents have not been examined. METHODS: Twelve- to 17-year-old unmedicated females with major depressive or anxiety disorders or with no psychopathology underwent a comprehensive psychiatric assessment for this pilot study. A T1-weighted magnetic resonance imaging scan was obtained, segmented using Freesurfer. Serum ferritin concentration (sF) was measured. Correlational analyses examined the association between body iron stores, psychiatric symptom severity, and basal ganglia volumes, accounting for confounding variables. RESULTS: Forty females were enrolled, 73% having a major depressive and/or anxiety disorder, 35% with sF < 15 ng/mL, and 50% with sF < 20 ng/mL. Serum ferritin was inversely correlated with both anxiety and depressive symptom severity (r = -0.34, p < 0.04 and r = -0.30, p < 0.06, respectively). Participants with sF < 15 ng/mL exhibited more severe depressive and anxiety symptoms as did those with sF < 20 ng/mL. Moreover, after adjusting for age and total intracranial volume, sF was inversely associated with left caudate (Spearman's r = -0.46, p < 0.04), left putamen (r = -0.58, p < 0.005), and right putamen (r = -0.53, p < 0.01) volume. CONCLUSIONS: Brain iron may become depleted at a sF concentration higher than the established threshold to diagnose iron deficiency (i.e. 15 ng/mL), potentially disrupting brain maturation and contributing to the emergence of internalizing disorders in adolescents.

A Prospective Evaluation of Fatigue in Pediatric Brain Tumor Patients Treated With Radiation Therapy.

Background: Fatigue is a well-established consequence of cranial radiotherapy in survivors of pediatric brain tumor, but less is known about acute fatigue during radiotherapy treatment. This study aimed to longitudinally evaluate fatigue in newly diagnosed pediatric patients with brain tumors during treatment. Methods: Primary caregivers of pediatric patients with brain tumors completed the proxy-reported Parent Fatigue Scale assessments prior to radiotherapy and weekly during radiotherapy treatment. The association between clinical factors and fatigue at each assessment was evaluated with multiple linear regressions. A comparison of fatigue between radiation modalities was also analyzed. Results: A total of 33 caregivers completed pre-radiation fatigue assessments, with 29 reporting fatigue during radiotherapy. Patients were aged 3 to 16 years (M = 8.32) at diagnosis and diagnosed with medulloblastoma (n = 23), primitive neuroectodermal tumor (n = 2), ependymoma (n = 1), germ cell tumor (n = 1), pineoblastoma (n = 1), atypical teratoid rhabdoid (n = 1), and other unspecific tumors (n = 3). Moderate-to-severe fatigue was reported for the majority of patients (31/33; 94%) during treatment. Craniospinal irradiation dose was the only significant predictor of fatigue (p < .05), but this association was restricted to the first week of therapy and was attenuated by therapy completion. Discussion: Although fatigue is often considered a long-term consequence of cranial radiotherapy, this pilot study demonstrates that moderate-to-severe fatigue is pervasive prior to radiotherapy and persists throughout treatment in pediatric patients with brain tumors, regardless of radiation modality or clinical factors. Additional research is warranted to establish a link between acute and long-term fatigue and develop interventions to mitigate this adverse outcome.

Sex-Based Differences in Functional Brain Activity During Working Memory in Survivors of Pediatric Acute Lymphoblastic Leukemia.

BACKGROUND: Long-term survivors of pediatric acute lymphoblastic leukemia are at elevated risk for neurocognitive deficits and corresponding brain dysfunction. This study examined sex-based differences in functional neuroimaging outcomes in acute lymphoblastic leukemia survivors treated with chemotherapy alone. METHODS: Functional magnetic resonance imaging (fMRI) and neurocognitive testing were obtained in 123 survivors (46% male; median [min-max] age = 14.2 years [8.3-26.5 years]; time since diagnosis = 7.7 years [5.1-12.5 years]) treated on the St. Jude Total XV treatment protocol. Participants performed the n-back working memory task in a 3 T scanner. Functional neuroimaging data were processed (realigned, slice time corrected, normalized, smoothed) and analyzed using statistical parametric mapping with contrasts for 1-back and 2-back conditions, which reflect varying degrees of working memory and task load. Group-level fMRI contrasts were stratified by sex and adjusted for age and methotrexate exposure. Statistical tests were 2-sided (P < .05 statistical significance threshold). RESULTS: Relative to males, female survivors exhibited less activation (ie, reduced blood oxygen dependent-level signals) in the right parietal operculum, supramarginal gyrus and inferior occipital gyrus, and bilateral superior frontal medial gyrus during increased working memory load (family-wise error-corrected P = .004 to .008, adjusting for age and methotrexate dose). Female survivors were slower to correctly respond to the 2-back condition than males (P < .05), though there were no differences in overall accuracy. Performance accuracy was negatively correlated with fMRI activity in female survivors (Pearson's r = -0.39 to -0.29, P = .001 to .02), but not in males. CONCLUSIONS: These results suggest the working memory network is more impaired in female survivors than male survivors, which may contribute to ongoing functional deficits.

"Why We Keep Coming Back": Family and Provider Perspectives on Factors Influencing Long-term Follow-up for Pediatric Cancer Survivorship Care.

PURPOSE: The majority of childhood cancer survivors do not follow-up for long-term risk-based screening for recurrent illness and treatment late effects, despite a high prevalence of secondary morbidities. The primary aim of this study was to investigate factors that influence long-term follow-up for survivorship care, from the perspectives of providers, patients, and caregivers. MATERIALS AND METHODS: A semistructured interview was designed to elicit stakeholder perspectives on factors that facilitate or impede routine clinic visits after completion of cancer therapy. Results were analyzed using a qualitative framework method. RESULTS: Providers, patients, and caregivers identified a wide range of factors that might influence long-term follow-up for care. All respondents noted the importance of efficient clinical operations, resources such as parking, provider behaviors, rapport/attachment, and patient/family logistics. Compared with patients/caregivers, providers more frequently mentioned institutional operations, their own education and skills, patient/family understanding and motivation, and interpersonal processes such as communication style. Families more frequently mentioned clinic environment, and patients more frequently noted the importance of having a family member present, something neither providers nor caregivers reported. CONCLUSIONS: Providers, patients, and patient caregivers have different perspectives regarding factors that may influence follow-up for long-term survivorship care. Understanding these differences can help inform efforts to improve follow-up.

Structural and Functional Brain Imaging in Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia Treated With Chemotherapy: A Systematic Review.

Background: The effect of chemotherapy on brain development in long-term survivors of pediatric acute lymphoblastic leukemia (ALL) was systematically reviewed. Methods: A systematic search of Pubmed, Scopus, and PsycINFO databases was conducted to identify articles published between January 2000 and February 2020 that implemented magnetic resonance imaging to assess brain structure and function in pediatric ALL survivors (diagnosed younger than 21 years of age). The review included articles that were published on children diagnosed with ALL between 0 and 21 years of age and treated with chemotherapy-only protocols. Articles meeting the inclusion criteria described survivors on average of 5 years or more from diagnosis and were peer-reviewed articles and original studies. Results: The search yielded 1975 articles with 23 articles meeting inclusion criteria. The review revealed that survivors had statistically significant alterations in brain anatomy, most commonly a smaller hippocampus and impaired microstructural white matter integrity in frontal brain regions. Survivors also had impaired brain function including lower brain network efficiency and altered resting state connectivity. Survivors also displayed widespread reductions in brain activation (ie, frontal, temporal, parietal brain regions) during cognitive tasks. Conclusion: Although the neurotoxic effects of cancer treatment are reduced in the absence of cranial radiation, survivors treated on chemotherapy-only protocols still display long-term alterations in brain structure and function, which contribute to lifelong neurocognitive late effects.

Neurosurgical training and global health education: systematic review of challenges and benefits of in-country programs in the care of neural tube defects.

OBJECTIVE: The recognition that neurosurgeons harbor great potential to advocate for the care of individuals with neural tube defects (NTDs) globally has sounded as a clear call to action; however, neurosurgical care and training in low- and middle-income countries (LMICs) present unique challenges that must be considered. The objective of this study was to systematically review publications that describe the challenges and benefits of participating in neurosurgery-related training programs in LMICs in the service of individuals with NTDs. METHODS: Using MEDLINE (PubMed), the authors conducted a systematic review of English- and Spanish-language articles published from 1974 to 2019 that describe the experiences of in-country neurosurgery-related training programs in LMICs. The inclusion criteria were as follows-1) population/exposure: US residents, US neurosurgeons, and local in-country medical staff participating in neurosurgical training programs aimed at improving healthcare for individuals with NTDs; 2) comparison: qualitative studies; and 3) outcome: description of the challenges and benefits of neurosurgical training programs. Articles meeting these criteria were assessed within a global health education conceptual framework. RESULTS: Nine articles met the inclusion criteria, with the majority of the in-country neurosurgical training programs being seen in subregions of Africa (8/9 [89%]) and one in South/Central America. US-based residents and neurosurgeons who participated in global health neurosurgical training had increased exposure to rare diseases not common in the US, were given the opportunity to work with a collaborative team to educate local healthcare professionals, and had increased exposure to neurosurgical procedures involved in treating NTDs. US neurosurgeons agreed that participating in international training improved their own clinical practices but also recognized that identifying international partners, travel expenses, and interference with their current practice are major barriers to participating in global health education. In contrast, the local medical personnel learned surgical techniques from visiting neurosurgeons, had increased exposure to intraoperative decision-making, and were given guidance to improve postoperative care. The most significant challenges identified were difficulties in local long-term retention of trained fellows and staff, deficient infrastructure, and lower compensation offered for pediatric neurosurgery in comparison to adult care. CONCLUSIONS: The challenges and benefits of international neurosurgical training programs need to be considered to effectively promote the development of neurosurgical care for individuals with NTDs in LMICs. In this global health paradigm, future work needs to investigate further the in-country professionals' perspective, as well as the related outcomes.

Towards Guideline-Based Management of Tethered Cord Syndrome in Spina Bifida: A Global Health Paradigm Shift in the Era of Prenatal Surgery.

An estimated 60% of the world's population lives in Asia, where the incidence of neural tube defects is high. Aware that tethered cord syndrome (TCS) is an important comorbidity, the purpose of this systematic review was to explore the treatment of TCS among individuals living with spina bifida (SB) in Asia. MEDLINE and Embase databases were searched for relevant studies published from January 2000 to June 2018. Search terms such as 'spinal dysraphism,' 'spinabifida,' 'diastematomyelia,' 'lipomeningocele,' 'lypomyelomeningocele,' 'meningomyelocele,' and 'tethered cord syndrome' were used in diverse combinations. Of the 1,290 articles that were identified in accordance with PRISMA (Preferred Items for Systematic Reviews and Meta-Analyses) guidelines, 15 Asia-based studies met the inclusion criteria. Significant differences in the diagnostic criteria and management of TCS were documented. As the surgical techniques for prenatal closure of the spinal defect continue to evolve, their adoption internationally is likely to continue. In this setting, a clear and evidence-based approach to the definition and management of TCS is essential. The recent publication by the Spina Bifida Association of America of their updated care guidelines may serve as a tool used to promote a systematized approach to diagnosing and treating TCS among individuals with SB in the region, as well as globally.