MRI morphometric and neuropsychological correlates of long-term memory in survivors of childhood leukemia

Contribution of Fatigue to Cognitive Dysfunction in Childhood Acute Lymphoblastic Leukemia Survivors

Late effects such as neurocognitive issues and fatigue have been reported in childhood acute lymphoblastic leukemia (cALL) survivors. Yet, their association is often poorly understood. In this study, we wished to (1) describe neurocognitive difficulties and fatigue in a well-characterized cohort of long-term cALL survivors and (2) explore the risk of having neurocognitive deficits as a function of fatigue. Childhood ALL survivors (N = 285) from three Canadian treatment centers completed the DIVERGT battery of cognitive tests and the PedsQL Multidimensional Fatigue Scale. We performed logistic regressions to assess the risk of a survivor to show cognitive deficits (<2.0 SD) depending on their fatigue levels. At least one cognitive deficit on the DIVERGT was present in 31% of participants. Domains primarily affected were working memory, fine motor skills, and verbal fluency. Sleep/rest fatigue in youths was higher than norms (d = 0.35). The risk for cognitive deficits increased independently with levels of fatigue in the domains of cognitive speed and flexibility, working memory, and verbal fluency. For every 10-point increase on general or sleep/rest fatigue on the 0-100 scale, there was a median +23-35% risk of showing a deficit among the 7 tasks significantly associated with fatigue. Fatigue may constitute a complementary target when searching to mitigate cognitive issues in this population.

A meta-analysis of the relation between hippocampal volume and memory ability in typically developing children and adolescents

Memory is supported by a network of brain regions, with the hippocampus serving a critical role in this cognitive process. Previous meta‐analyses on the association between hippocampal structure and memory have largely focused on adults. Multiple studies have since suggested that hippocampal volume is related to memory performance in children and adolescents; however, the strength and direction of this relation varies across reports, and thus, remains unclear. To further understand this brain–behavior relation, we conducted a meta‐analysis to investigate the association between hippocampal volume (assessed as total volume) and memory during typical development. Across 25 studies and 61 memory outcomes with 1357 participants, results showed a small, but significant, positive association between total hippocampal volume and memory performance. Estimates of the variability across studies in the relation between total volume and memory were not explained by differences in memory task type (delayed vs. immediate; relational vs. nonrelational), participant age range, or the method of normalization of hippocampal volumes. Overall, findings suggest that larger total hippocampal volume relates to better memory performance in children and adolescents and that this relation is similar across the memory types and age ranges assessed. To facilitate enhanced generalization across studies in the future, we discuss considerations for the field moving forward.

Changes in neurocognitive function and central nervous system structure in childhood acute lymphoblastic leukaemia survivors after treatment: a meta-analysis

Acute lymphoblastic leukaemia (ALL) is the most common malignancy in children. Although the survival rate has increased dramatically over the last decades, patients struggle with the adverse side effects of treatment. Treatment for ALL includes chemotherapy and irradiation - both of which are linked to cognitive impairments and alterations in central nervous system (CNS) structure and function detected by neuroimaging and in neurocognitive studies. The present article is a meta-analysis of the existing evidence for the mechanisms underlying changes in the CNS and neurocognitive function in ALL survivors after treatment. We found that compared with controls, ALL survivors develop: (i) cognitive sequelae in intelligence, academics, attention, memory, processing speed and executive function domains; (ii) decreased grey and white matter volume in cortical and several subcortical brain regions, with functional changes particularly in frontal regions and the hippocampus; (iii) neurocognitive impairments related to CNS changes; and (iv) reduction, but not resolution, of late neurocognitive sequelae in patients in whom prophylactic irradiation was replaced by systemic/intrathecal chemotherapy. Continued work with advanced functional magnetic resonance imaging techniques will hopefully allow the detection of early CNS changes as biomarkers to help guide early diagnosis and intervention for neurocognitive defects in patients with childhood ALL.

Brain Connectivity and Cognitive Flexibility in Nonirradiated Adult Survivors of Childhood Leukemia

Background

This study aimed to assess functional and structural brain connectivity in adult childhood leukemia survivors and the link with cognitive functioning and previously identified risk factors such as intrathecal methotrexate dose and age at start of therapy.

Methods

Thirty-one nonirradiated adult childhood leukemia survivors and 35 controls underwent cognitive testing and multimodal magnetic resonance imaging (resting state functional MRI, T1-weighted, diffusion-weighted, and myelin water imaging [MWI]). Analyses included dual regression, voxel-based morphometry, advanced diffusion, and MWI modeling techniques besides stepwise discriminant function analysis to identify the most affected executive cognitive domain. Correlations with discrete intrathecal MTX doses and (semi)continuous variables were calculated using Spearman's rank and Pearson's correlation, respectively. All correlation tests were two-sided. Positive and negative T-contrasts in functional and structural MRI analysis were one-sided.

Results

Survivors demonstrated lower functional connectivity between the default mode network (DMN) and inferior temporal gyrus (ITG; P < .008). Additionally, we observed higher fractional anisotropy (FA; P = .04) and lower orientation dispersion index (ODI; P = .008) at the left centrum semiovale, which could-given that several fiber bundles cross this region-suggest selective reduced integrity of the respective white matter tracts. Set shifting reaction time, a measure of cognitive flexibility, was mostly impaired and correlated with lower FA (r = -0.53, P = .003) and higher ODI (r = 0.40, P = .04) in survivors but not with DMN-ITG connectivity. There were no statistically significant differences between survivors and controls in WM or GM volume, nor was there a statistically significant correlation between imaging measurements and age at start of therapy or intrathecal methotrexate dose.

Conclusions

Adult, nonirradiated childhood leukemia survivors show altered brain connectivity, which is linked with cognitive flexibility.

Neurodevelopmental consequences of pediatric cancer and its treatment: applying an early adversity framework to understanding cognitive, behavioral, and emotional outcomes

Today, children are surviving pediatric cancer at unprecedented rates, making it one of modern medicine's true success stories. However, we are increasingly becoming aware of several deleterious effects of cancer and the subsequent "cure" that extend beyond physical sequelae. Indeed, survivors of childhood cancer commonly report cognitive, emotional, and psychological difficulties, including attentional difficulties, anxiety, and posttraumatic stress symptoms (PTSS). Cognitive late- and long-term effects have been largely attributed to neurotoxic effects of cancer treatments (e.g., chemotherapy, cranial irradiation, surgery) on brain development. The role of childhood adversity in pediatric cancer - namely, the presence of a life-threatening disease and endurance of invasive medical procedures - has been largely ignored in the existing neuroscientific literature, despite compelling research by our group and others showing that exposure to more commonly studied adverse childhood experiences (i.e., domestic and community violence, physical, sexual, and emotional abuse) strongly imprints on neural development. While these adverse childhood experiences are different in many ways from the experience of childhood cancer (e.g., context, nature, source), they do share a common element of exposure to threat (i.e., threat to life or physical integrity). Therefore, we argue that the double hit of early threat and cancer treatments likely alters neural development, and ultimately, cognitive, behavioral, and emotional outcomes. In this paper, we (1) review the existing neuroimaging research on child, adolescent, and adult survivors of childhood cancer, (2) summarize gaps in our current understanding, (3) propose a novel neurobiological framework that characterizes childhood cancer as a type of childhood adversity, particularly a form of early threat, focusing on development of the hippocampus and the salience and emotion network (SEN), and (4) outline future directions for research.

A Cross-sectional Study of Two Chemotherapy Protocols on Long Term Neurocognitive Functions in Egyptian Children Surviving Acute Lymphoblastic Leukemia

INTRODUCTION

Subtle neurocognitive deficits have been recently observed in Acute Lymphoblastic Leukemia (ALL) survivors.

AIM

We aim to assess the neurocognitive functions of ALL survivors who had been treated with chemotherapy only using two different protocols, and to identify treatment-related risk factors.

PATIENTS AND METHODS

We carried a multicenter study involving 3 pediatric oncology centers on 100 children who were treated for ALL. Fifty patients were treated by the modified Children's Cancer Group (CCG) 1991 protocol with low dose methotrexate and 50 children were treated by Total XV protocol with high dose methotrexate. Fifty healthy children were included as a control group. Psychometric assessment using Arabic version of Wechsler intelligence scale for children (WISC III) was performed for all patients and controls.

RESULTS

Patients had significantly lower mean full scale IQ, performance IQ and verbal IQ than controls. Patients ≤ 5 years at diagnosis had significantly lower mean full scale IQ and performance IQ than patients>5 years at diagnosis, while the verbal IQ showed no significant difference between both age groups. Female patients had significantly lower mean full scale IQ, performance IQ and verbal IQthan males. Patients who received Total XV protocol with high dose methotrexate had significantly lower mean full scale IQ, performance IQ and verbal IQ than patients who received modified CCG 1991 protocol with low dose methotrexate.

CONCLUSIONS

CNS directed chemotherapy might appear to affect neurocognitive functions in children with ALL, which is more significant in young children at diagnosis, in girls and in those receiving high dose methotrexate.

Neurocognitive Predictors of Academic Outcomes Among Childhood Leukemia Survivors

BACKGROUND

Acute lymphoblastic leukemia is the most common pediatric cancer, and survival approaches 90%. Acute lymphoblastic leukemia survivors are more likely than healthy peers or siblings to experience academic underachievement, yet little is known about neurocognitive predictors of academic outcomes.

OBJECTIVES

Objectives were to compare neurocognitive abilities to age-adjusted standardized norms, examine change over time in neurocognitive abilities, and establish neurocognitive predictors of academic outcomes.

METHODS

Seventy-one children were followed over the course of therapy. Cognitive abilities were assessed during induction when the child was in remission (baseline) and annually for 3 years (years 1, 2, and 3). Reading and mathematics abilities were assessed at year 3.

RESULTS

Fine motor dexterity was significantly below age-adjusted norms at all data points but showed improvement over time. Baseline visual-motor integration was within the reference range but significantly declined by year 3, and mean scores at years 2 and 3 were significantly below age-adjusted norms. Verbal short-term memory was significantly below age-adjusted norms at all assessments. Visual-motor integration predicted reading and mathematics abilities. Verbal short-term memory predicted reading abilities, and visual short-term memory predicted mathematics abilities.

CONCLUSIONS

Central nervous system-directed therapy is associated with specific neurocognitive problems. Visual-spatial skills and verbal and visual short-term memory predict academic outcomes.

IMPLICATIONS FOR PRACTICE

Early assessment of visual-spatial perception and short-term memory can identify children at risk of academic problems. Children who are at risk of academic problems could benefit from a school-based individual educational program and/or educational intervention.

The relationship between cognitive and neuroimaging outcomes in children treated for acute lymphoblastic leukemia with chemotherapy only: A systematic review

Cognitive late-effects have been identified in patients treated with chemotherapy-only protocols for childhood acute lymphoblastic leukemia (ALL), yet the underlying neuropathology is not well understood. This review synthesized recent findings from eight articles investigating the relationship between neurocognitive and neuroimaging outcomes for patients treated for ALL with chemotherapy-only protocols. Reported cognitive domains, imaging methods, and neuroanatomy examined were variable. Despite this, 62.5% (n = 5) of the reviewed studies found a significant relationship between cognitive and imaging outcomes. Greater understanding of the effects of treatment on neuroanatomy and cognitive outcomes is critical for proactively managing ALL cognitive late-effects. Research directions are suggested.

Leukemias in Children

Childhood cancers are rare but an important cause of morbidity and mortality in children younger than 15 y of age. Common childhood malignancies include leukemias (commonest, 30-40%), brain tumors (20%) and lymphoma (12%) followed by neuroblastoma, retinoblastoma and tumors arising from soft tissues, bones and gonads. Leukemias, the commonest childhood cancer, arise from clonal proliferation of abnormal hematopoietic cells leading to disruption of normal marrow function and marrow failure. The various clinical manifestations of leukemia result from unregulated proliferation of the malignant clone and bone marrow failure. There are two main subtypes, the commoner, acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). A small proportion may have chronic myeloid leukemia (CML) and juvenile myelomonocytic leukemia (JMML). A systematic approach is necessary for diagnosis. Treatment should be initiated as early as possible to avoid complications. A timely referral to a cancer center must be done if facilities for diagnosis/treatment, management of complications and provision for supportive care are not available at the treating center.

Neurocognitive outcomes in long-term survivors of childhood acute lymphoblastic leukemia treated on contemporary treatment protocols: A systematic review

The intensified administration of chemotherapeutic drugs has gradually replaced cranial radiation therapy (CRT) for the treatment of childhood acute lymphoblastic leukemia (ALL). While CRT is often implicated in neurocognitive impairment in ALL survivors, there is a paucity of the literature that evaluates the persistence of neurocognitive deficits in long-term survivors of pediatric ALL who were treated with contemporary chemotherapy-only protocols. Results from this systematic review concurred to the probable cognitive-sparing effect of chemotherapy-based protocols over CRT in long-term survivors. However, coupled with multiple intrinsic and extrinsic factors, survivors who received chemotherapy treatment still suffered from apparent cognitive impairment, particularly in the attention and executive function domains. Notably, there is evidence to suggest that the late neurotoxic effect of methotrexate on survivors' neurocognitive performance may be dose-related. This review also recommends future pharmacokinetic, neuroimaging and genetic studies to illuminate the multifactorial nature of this subject matter and discusses the potential value of neurochemical, physiological, inflammatory and genetic markers for the prediction of susceptibility to neurocognitive impairment in long-term survivors of childhood ALL.

Increase in oxidative stress as measured by cerebrospinal fluid lipid peroxidation during treatment for childhood acute lymphoblastic leukemia

Five-year survival from childhood acute lymphoblastic leukemia (ALL) approaches 90%, but 40% of survivors experience central nervous system (CNS) treatment-related cognitive problems. Despite considerable evidence for cognitive problems, less is known about mechanisms of neurological injury. Our purpose was to investigate oxidative stress, measured by lipid peroxidation, as a mechanism of CNS treatment-related neurological injury. The sample included 55 children (mean age at diagnosis=6.84 y, SD=3.40) who received intrathecal and intravenous chemotherapy for CNS-directed treatment according to Children's Oncology Group protocols. Glycerophospholipids were extracted from cerebrospinal fluid samples obtained at diagnosis and during intrathecal chemotherapy administration. Unoxidized and oxidized phosphatidylcholine (PC) and phosphatidylinositol (PI) were measured by normal phase high-performance liquid chromatography with diode array detection, and analyzed with a general linear model for repeated measures analysis of variance. Compared with the diagnostic cerebrospinal fluid sample, unoxidized and oxidized PC and PI increased significantly across treatment phases. Amount of intravenous methotrexate received was significantly correlated with oxidized PI, and age at time of ALL diagnosis was significantly associated with oxidized PC. These findings support our hypothesis that oxidative stress is a mechanism of neurological injury associated with CNS-directed treatment for ALL.

Assessment of neuropsychological late effects in survivors of childhood leukemia

The neurologic dysfunctions caused by treatment may affect health and quality of life in survivors of childhood leukemia. The objective of this study was to identify the neuropsychological late effects of leukemia treatment to provide an assessment about the degree and incidence of these late effects. Neurological and ophtalmological examination, cranial magnetic resonance imaging (MRI), auditory and neurocognitive tests, and questionnaires of quality of life were performed to 44 acute leukemia survivors at least 5 years after diagnosis. Median time since completion of chemotherapy was 7.5 years (2-18) and median age at the time of the study was 16.4 years (8-31). At least one or more late effects detected by physical examination (PE), neurological tests, or neurocognitive tests encountered in 80% of the patients, and 64% of the patients specified at least one complaint in the quality of life questionnaire. MRI revealed pathological findings in 18% and electroencephalogram (EEG) abnormalities were present in 9% of the patients. Evaluation of total intelligence scores revealed that 30% of patients' IQ scores were <80 and 70% of the patients' scores demonstrated neurocognitive dysfunctions. The patients >6 years at the time of diagnosis were found to have more psychological problems and higher rates of smoking and alcohol consumption. The most frequent complaint was headache and the most common problem in school was denoted as difficulty in concentration. Our study demonstrated that most of the survivors of childhood leukemia are at risk of developing neuropsycological late effects.

Neurocognitive outcome and white matter anisotropy in childhood acute lymphoblastic leukemia survivors treated with different protocols

Neurocognitive outcome affects the quality of life of ALL survivors. This study is aimed to assess the prevalence of neurocognitive dysfunction by psychometric and imaging tools in survivors of childhood ALL, treated with 3 different protocols and the effect of time elapsed since the end of chemotherapy. Sixty-two ALL survivors aged 6-18 years and treated in the period 1997-2007 and 60 healthy age and sex matched controls were subjected to neurocognitive testing using Wechsler Intelligence Scale for Children, Benton visual retention (BVRT) and Trail Making test (TMT), followed by diffusion weighed and diffusion tensor MRI for calculation of fraction anisotropy (FA). Survivors underwent revision of protocol and type of CNS therapy. Three different protocols were used: modified BFM 83, BFM 90, and CCG. Survivors treated with modified CCG protocol showed a significant decrease in all cognitive tests compared to control (p<.05); BFM 90 group had a significant lower IQ and longer TMT compared to both control and BFM 83 group and no significant difference was found in results of cognitive tests between BFM 83 and control group. Frontal FA was lower in CCG treated group compared to control, BFM 90 and BFM 83 groups (p<.05); meanwhile it was significantly lower in BFM 90 and BFM 83 groups compared to control group. We concluded that patients treated with modified CCG protocol showed the worst neurocognitive outcome among three assessed protocols. Frontal lobe FA might be an early marker for predicting the neurotoxicity in childhood ALL survivors.

Effects of chemotherapy on neurocognitive function in children with acute lymphoblastic leukemia: a critical review of the literature

Chemotherapy-only treatment has increasingly become the standard of treatment for childhood acute lymphoblastic leukemia (ALL). The objective of this review is to assess the present state of knowledge of the neurocognitive effects of central nervous system (CNS)-directed chemotherapy in children with ALL, and to formulate directions for future research. We performed a review of studies published since 1997, that included an ALL group treated with chemotherapy only and a control group. Twenty-one studies met our inclusion criteria. There is evidence of subtle long-term neurocognitive deficits survivors of childhood ALL after treatment with chemotherapy only. These involve mainly processes of attention and of executive functioning, while global intellectual function is relatively preserved. Young age at diagnosis and female sex emerged as risk factors.

Neurologic toxicities of cancer therapies

Neurologic dysfunction is a well-recognized adverse effect of cancer therapeutics. The most common manifestations include peripheral neuropathy and encephalopathy. Often, symptoms resolve or improve upon removal of the offending agent; therefore, it is essential that clinicians recognize the symptoms and signs of injury. Occasionally, symptoms persist or develop after discontinuation of medication and may culminate in disability and diminished quality of life. As our understanding of neurotoxicity improves, medications with less potential for injury may be developed. In addition, potential antidotes to prevent or reverse injury may emerge. This review focuses on the clinical features, mechanisms, and possible therapeutics of the neurotoxicity of chemotherapy. In particular, oxaliplatin, thalidomide, methotrexate, ifosfamide, cytarabine, amifostine, acetyl-L-carnitine, methylene blue, cytokines, and neurotrophins are discussed.