Evidence of change in brain activity among childhood cancer survivors participating in a cognitive remediation program

Functional Alteration in the Brain Due to Tumour Invasion in Paediatric Patients: A Systematic Review

Working memory, language and speech abilities, motor skills, and visual abilities are often impaired in children with brain tumours. This is because tumours can invade the brain's functional areas and cause alterations to the neuronal networks. However, it is unclear what the mechanism of tumour invasion is and how various treatments can cause cognitive impairment. Therefore, this study aims to systematically evaluate the effects of tumour invasion on the cognitive, language, motor, and visual abilities of paediatric patients, as well as discuss the alterations and modifications in neuronal networks and anatomy. The electronic database, PubMed, was used to find relevant studies. The studies were systematically reviewed based on the type and location of brain tumours, cognitive assessment, and pre- and post-operative deficits experienced by patients. Sixteen studies were selected based on the inclusion and exclusion criteria following the guidelines from PRISMA. Most studies agree that tumour invasion in the brain causes cognitive dysfunction and alteration in patients. The effects of a tumour on cognition, language, motor, and visual abilities depend on the type of tumour and its location in the brain. The alteration to the neuronal networks is also dependent on the type and location of the tumour. However, the default mode network (DMN) is the most affected network, regardless of the tumour type and location.Furthermore, our findings suggest that different treatment types can also contribute to patients' cognitive function to improve or deteriorate. Deficits that persisted or were acquired after surgery could result from surgical manipulation or the progression of the tumour's growth. Meanwhile, recovery from the deficits indicated that the brain has the ability to recover and reorganise itself.

Functional network alterations in young brain tumor patients with radiotherapy-induced memory impairments and vascular injury

Background

Cognitive impairment and cerebral microbleeds (CMBs) are long-term side-effects of cranial radiation therapy (RT). Previously we showed that memory function is disrupted in young patients and that the rate of cognitive decline correlates with CMB development. However, vascular injury alone cannot explain RT-induced cognitive decline. Here we use resting-state functional MRI (rsfMRI) to further investigate the complex mechanisms underlying memory impairment after RT.

Methods

Nineteen young patients previously treated with or without focal or whole-brain RT for a brain tumor underwent cognitive testing followed by 7T rsfMRI and susceptibility-weighted imaging for CMB detection. Global brain modularity and efficiency, and rsfMRI signal variability within the dorsal attention, salience, and frontoparietal networks were computed. We evaluated whether MR metrics could distinguish age- and sex-matched controls (N = 19) from patients and differentiate patients based on RT exposure and aggressiveness. We also related MR metrics with memory performance, CMB burden, and risk factors for cognitive decline after RT.

Results

Compared to controls, patients exhibited widespread hyperconnectivity, similar modularity, and significantly increased efficiency (p < 0.001) and network variability (p < 0.001). The most abnormal values were detected in patients treated with high dose whole-brain RT, having supratentorial tumors, and who did not undergo RT but had hydrocephalus. MR metrics and memory performance were correlated (R = 0.34–0.53), though MR metrics were more strongly related to risk factors for cognitive worsening and CMB burden with evidence of functional recovery.

Conclusions

MR metrics describing brain connectivity and variability represent promising candidate imaging biomarkers for monitoring of long-term cognitive side-effects after RT.

Posterior Fossa Tumor Rehabilitation: An Up-to-Date Overview

This narrative review highlights the latest achievements in the field of post-surgical rehabilitation of posterior fossa tumors. Studies investigating the effects of cognitive rehabilitation programs have been considered, following a comprehensive literature search in the scientific electronic databases: Pubmed, Scopus, Plos One, and ScienceDirect. This review investigates the effects of cognitive remediation, with specific highlights for single cognitive domains. The results revealed that in spite of the increasing number of children who survive into adulthood, very few studies investigated the effects of rehabilitation programs in this specific population. This study details new, promising therapeutic opportunities for children after brain surgery. More research in this filed is needed to identify the most effective protocols for clinical use.

Cross-translational models of late-onset cognitive sequelae and their treatment in pediatric brain tumor survivors

Pediatric brain tumor treatments have a high success rate, but survivors are at risk of cognitive sequelae that impact long-term quality of life. We summarize recent clinical and animal model research addressing pathogenesis or evaluating candidate interventions for treatment-induced cognitive sequelae. Assayed interventions encompass a broad range of approaches, including modifications to radiotherapy, modulation of immune response, prevention of treatment-induced cell loss or promotion of cell renewal, manipulation of neuronal signaling, and lifestyle/environmental adjustments. We further emphasize the potential of neuroimaging as a key component of cross-translation to contextualize laboratory research within broader clinical findings. This cross-translational approach has the potential to accelerate discovery to improve pediatric cancer survivors' long-term quality of life.

Cognitive function of children and adolescent survivors of acute lymphoblastic leukemia: A meta-analysis

Pediatric cancer and its treatment may have an impact on the neurocognitive functions of childhood cancer survivors (CCS). The aim of the present meta-analysis was to compare the intelligence quotient (IQ) scores between CCS of acute lymphoblastic leukemia (ALL) and controls. A comprehensive electronic search identified original research articles that reported scores of the Wechsler Intelligence Scale (WISC; WISC-III, WISC-IV and WISC-R) for children and adolescents, aged 6-16 years at evaluation, survivors of ALL and healthy controls. The included CCS had completed anticancer treatment and were in remission at the time of assessment. A total of 16 studies were included in the meta-analysis, out of 128 extracted studies, and involved a total of 1,676 children and adolescents: 991 CCS (ALL) and 685 healthy controls. Among the studies, a random effects model revealed a moderate estimate of effect size [standardized mean difference (SMD), -0.78; 95% CI, -1.05 to -0.50], indicating that the WISC scores for total IQ were significantly lower in the CCS than in the controls. The mean total IQ range was 85.2-107.2 in the CCS and 88.4-114.1 in the controls. The difference in the mean total IQ between controls and CCS ranged from -13.8 to 20.6. As regards the WISC scores for verbal IQ, 11 studies were included. A random effects model revealed a moderate estimate of effect size (SMD, -0.71; 95% CI, -1.05 to -0.38), indicating that the WISC scores for verbal IQ were significantly lower in the CCS than in the controls. Among the 9 studies that had available data for performance IQ scores, a fixed effect model revealed a moderate estimate of effect size (SMD, -0.80; 95% CI, -1.09 to -0.52), indicating that the WISC scores for performance IQ were significantly lower in the CCS than in the controls. As the survival rates of children and adolescents with ALL are steadily increasing, regular, lifelong follow-up for neurocognitive late effects is imperative in order to improve their education and employment prospects and overall, their quality of life.

Training-Induced Neural Plasticity in Youth: A Systematic Review of Structural and Functional MRI Studies

Experience-dependent neural plasticity is high in the developing brain, presenting a unique window of opportunity for training. To optimize existing training programs and develop new interventions, it is important to understand what processes take place in the developing brain during training. Here, we systematically review MRI-based evidence of training-induced neural plasticity in children and adolescents. A total of 71 articles were included in the review. Significant changes in brain activation, structure, microstructure, and structural and functional connectivity were reported with different types of trainings in the majority (87%) of the studies. Significant correlation of performance improvement with neural changes was reported in 51% of the studies. Yet, only 48% of the studies had a control condition. Overall, the review supports the hypothesized neural changes with training while at the same time charting empirical and methodological desiderata for future research.

Post-operative cerebellar mutism syndrome: rehabilitation issues

INTRODUCTION

Tumors of the cerebellum are the most common brain tumors in children. Modern treatment and aggressive surgery have improved the overall survival. Consequently, growing numbers of survivors are at high risk for developing adverse and long-term neurological deficits including deficits of cognition, behavior, speech, and language. Post-operative cerebellar mutism syndrome (pCMS) is a well-known and frequently occurring complication of cerebellar tumor surgery in children. In the acute stage, children with pCMS may show deterioration of cerebellar motor function as well as pyramidal and cranial neuropathies. Most debilitating is the mutism or the severe reduction of speech and a range of neurobehavioral symptoms that may occur. In the long term, children that recover from pCMS continue to have more motor, behavioral, and cognitive problems than children who did not develop pCMS after cerebellar tumor surgery. The severity of these long-term sequelae seems to be related to the length of the mute phase.

AIM OF THIS NARRATIVE REVIEW

The impact of pCMS on patients and families cannot be overstated. This contribution aims to discuss the present knowledge on the natural course, recovery, and rehabilitation of children with pCMS. We suggest future priorities in developing rehabilitation programs in order to improve the long-term quality of life and participation of children after cerebellar tumor surgery and after pCMS in particular.

Early adolescent language development following intrathecal chemotherapy for acute lymphoblastic leukaemia

PURPOSE

Central nervous system (CNS) prophylaxis in the treatment of childhood acute lymphoblastic leukaemia (ALL) is routinely achieved through intrathecal chemotherapy (ITC). The presence of high level language deficits in older children who received CNS-directed ITC for ALL in early childhood is yet to be elucidated, with previous research suggesting that high level language deficits may appear later in ALL survivors' development at an age when these skills typically emerge.

METHOD

A test battery covering foundational language skills and higher-order language skills was administered to five participants (aged 10-15 years) with a history of ITC for ALL. Conversion of each child's language performance scores to z scores allowed for clinical interpretation of data across the language areas tested.

RESULT

Foundational language skills were, in general, of no clinical concern. Three of the five children presented with clinically impaired language skills in areas including resolving ambiguity, making inferences and composing novel sentences. Performance variation between the participants and within the individual participants was noted.

CONCLUSION

Given the importance of early adolescent language abilities to academic and social development in late primary and secondary schooling, these preliminary findings suggest further research into emerging adolescent language abilities following ITC for ALL is warranted.

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.

Functional MRI in medulloblastoma survivors supports prophylactic reading intervention during tumor treatment

Development of reading skills is vulnerable to disruption in children treated for brain tumors. Interventions, remedial and prophylactic, are needed to mitigate reading and other learning difficulties faced by survivors. A functional magnetic resonance imaging (fMRI) study was conducted to investigate long-term effects of a prophylactic reading intervention administered during radiation therapy in children treated for medulloblastoma. The fMRI study included 19 reading-intervention (age 11.7 ± 0.6 years) and 21 standard-of-care (age 12.1 ± 0.6 years) medulloblastoma survivors, and 21 typically developing children (age 12.3 ± 0.6 years). The survivors were 2.5 [1.2, 5.4] years after completion of tumor therapies and reading-intervention survivors were 2.9 [1.6, 5.9] years after intervention. Five fMRI tasks (Rapid Automatized Naming, Continuous Performance Test using faces and letters, orthographic and phonological processing of letter pairs, implicit word reading, and story reading) were used to probe reading-related neural activation. Woodcock-Johnson Reading Fluency, Word Attack, and Sound Awareness subtests were used to evaluate reading abilities. At the time of fMRI, Sound Awareness scores were significantly higher in the reading-intervention group than in the standard-of-care group (p = 0.046). Brain activation during the fMRI tasks was detected in left inferior frontal, temporal, ventral occipitotemporal, and subcortical regions, and differed among the groups (p < 0.05, FWE). The pattern of group activation differences, across brain areas and tasks, was a normative trend in the reading-intervention group. Standardized reading scores and patterns of brain activation provide evidence of long-term effects of prophylactic reading intervention in children treated for medulloblastoma.

Non-graduation after comprehensive school, and early retirement but not unemployment are prominent in childhood cancer survivors-a Finnish registry-based study

BACKGROUND

In order to assess neurocognitive and social outcomes after childhood cancer, we explored the educational and vocational attainments of Finnish survivors in comparison to matched population controls.

METHODS

From national registries, we identified survivors (n = 3243) born from 1960 to 1992 and aged below 16 at cancer diagnosis (years 1964-2009) as well as their controls (n = 16,215). Data on educational achievements, yearly income, employment status, and retirement were retrieved from Statistics Finland.

RESULTS

The median (range) age at study was 28 (17-50) years. The proportion of those with no education after comprehensive school was higher than controls for all the diagnostic groups: brain tumor (BT) (33.5 vs 23.0 %), solid tumor (ST) (25.0 vs 21.4 %), and leukemia/NHL (29.2 vs 23.1 %). Odds ratios (OR) for unemployment were not significantly elevated in any survivor group compared to controls, but OR for being retired was elevated in each survivor group (BT 14.8, ST 2.2, leukemia/NHL 4.0). Irradiation significantly increased that OR only in BT survivors. Leukemia/NHL survivors treated after 1992 had lower risk for early retirement (OR 0.6) compared to those diagnosed earlier.

CONCLUSIONS

Survivors had higher frequencies than controls for lacking further education after comprehensive school. Unemployment was not common, but risk for early retirement was significantly increased in each three survivor group.

IMPLICATIONS FOR CANCER SURVIVORS

Reassuring is that premature retirement was less common during the most recent treatment era. Screening and follow-up of psychosocial performance more effectively might be essential, and there is a need for studies on possibility for effective rehabilitation of the survivors.

Monitoring and Assessment of Neuropsychological Outcomes as a Standard of Care in Pediatric Oncology

Central nervous system cancers or exposure to CNS-directed therapies increase risk for neuropsychological deficits. There are no accepted guidelines for assessment of neuropsychological functioning in this population. A multifaceted literature search was conducted and relevant literature reviewed to inform the guidelines. Studies of neuropsychological outcomes are widely documented in the pediatric oncology literature. There is strong evidence of need for neuropsychological assessment, but insufficient evidence to guide the timing of assessment, nor to recommend specific interventions. Children with brain tumors and others at high risk for neuropsychological deficits should be monitored and assessed for neuropsychological deficits.

Functional and neuropsychological late outcomes in posterior fossa tumors in children

Tumors of the posterior fossa (PF) account for up to 60 % of all childhood intracranial tumors. Over the last decades, the mortality rate of children with posterior fossa tumors has gradually decreased. While survival has been the primary objective in most reports, quality of survival increasingly appears to be an important indicator of a successful outcome. Children with a PF tumor can sustain damage to the cerebellum and other brain structures from the tumor itself, concomitant hydrocephalus, the consequences of treatment (surgery, chemotherapy, radiotherapy), or a combination of these factors. Together, these contribute to long-term sequelae in physical functioning, neuropsychological late outcomes (including academic outcome, working memory, perception and estimation of time, and selective attention, long-term neuromotor speech deficits, and executive functioning). Long-term quality of life can also be affected by endocrinological complication or the occurrence of secondary tumors. A significant proportion of survivors of PF tumors require long-term special education services and have reduced rates of high school graduation and employment. Interventions to improve neuropsychological functioning in childhood PF tumor survivors include (1) pharmacological interventions (such as methylphenidate, modafinil, or donepezil), (2) cognitive remediation, and (3) home-based computerized cognitive training. In order to achieve the best possible outcome for survivors, and ultimately minimize long-term complications, new interventions must be developed to prevent and ameliorate the neuro-toxic effects experienced by these children.

Cognitive training programs for childhood cancer patients and survivors: A critical review and future directions

A robust literature has developed documenting neurocognitive late effects in survivors of leukemia and central nervous system (CNS) tumors, the most frequent cancer diagnoses of childhood. Patterns of late effects include deficits in attention and concentration, working memory, processing speed, and executive function, as well as other domains. As childhood cancer survivors are living longer, ameliorating deficits both in broad and specific neurocognitive domains has been increasingly recognized as an endeavor of paramount importance. Interventions to improve cognitive functioning were first applied to the field of pediatric oncology in the 1990s, based on strategies used effectively with adults who had sustained a traumatic brain injury (TBI). Compilation and modification of these techniques has led to the development of structured cognitive training programs, with the effectiveness and feasibility of such interventions currently an active area of research. Consequently, the purpose of this critical review is to: (1) review cognitive training programs intended to remediate or prevent neurocognitive deficits in pediatric cancer patients and survivors, (2) critically analyze training program strengths and weaknesses to inform practice, and (3) provide recommendations for future directions of clinical care and research.

Concentration, working speed and memory: cognitive problems in young childhood cancer survivors and their siblings

BACKGROUND

Cognitive problems can have a negative effect on a person's education, but little is known about cognitive problems in young childhood cancer survivors (survivors). This study compared cognitive problems between survivors and their siblings, determined if cognitive problems decreased during recent treatment periods and identified characteristics associated with the presence of a cognitive problem in survivors.

METHODS

As part of the Swiss Childhood Cancer Survivor Study, a questionnaire was sent to all survivors, aged 8-20 years, registered in the Swiss Childhood Cancer Registry, diagnosed at age <16 years, who had survived ≥ 5 years. Parent-reported (aged 8-15 years) and self-reported (aged 16-20 years) cognitive problems (concentration, working speed, memory) were compared between survivors and siblings. Multivariable logistic regression was used to identify characteristics associated with cognitive problems in survivors.

RESULTS

Data from 840 survivors and 247 siblings were analyzed. More often than their siblings, survivors reported problems with concentration (12% vs. 6%; P = 0.020), slow working speed (20% vs. 8%; P = 0.001) or memory (33% vs. 15%; P < 0.001). Survivors from all treatment periods were more likely to report a cognitive problem than were siblings. Survivors of CNS tumors (OR = 2.82 compared to leukemia survivors, P < 0.001) and those who had received cranial irradiation (OR = 2.10, P = 0.010) were most severely affected.

CONCLUSION

Childhood cancer survivors, even those treated recently (2001-2005), remain at risk to develop cognitive problems, suggesting a need to improve therapies. Survivors with cognitive problems should be given the opportunity to enter special education programs.

[Neurocognitive outcome in childhood brain tumor survivors]

Advances in treatment have significantly improved the survival rate of children with brain tumour. This review describes risk factors of late neurocognitive effect, the different type of neurocognitive side effect according to the type of tumour and the rehabilitation. The best knowledge of cognitive sequelae allowed to propose supported appropriate and specific disorders including school facilities for younger and adaptation of professional situation for adults. Furthermore, this understanding allows to link with the patient's quality of life and to approach the person in its specificity and overall.

Clinical utility of the N-back task in functional neuroimaging studies of working memory

INTRODUCTION

N-back tasks are commonly used in functional neuroimaging studies to identify the neural mechanisms supporting working memory (WM). Despite widespread use, the clinical utility of these tasks is not well specified. This study compared N-back performance during functional magnetic resonance imaging (fMRI) with task data acquired outside of the scanner as a measure of reliability across environment. N-back task validity was examined in relation to performance and rater-based measures used clinically to assess working memory.

METHOD

Forty-three healthy adults completed verbal and object N-back tasks during fMRI scanning and outside the scanner. Task difficulty was varied parametrically (0, 1, and 2-back conditions). Order of N-back task completion was stratified by modality (verbal/object) and environment. Participants completed the Digit Span (DS) and provided self-ratings using the Behavior Rating Inventory of Executive Function (BRIEF-WM).

RESULTS

Mean verbal and object N-back accuracy was above 95% across load conditions; task difficulty was effectively manipulated across load conditions. Performance accuracy did not significantly differ by environment. N-back reaction time was slower during fMRI (F = 6.52, p = .01, ηp(2) = .13); participants were faster when initially completing tasks outside the scanner (ηp(2) = .10-.15). Verbal 2-back accuracy was significantly related to DS performance (r = .36, p = .02). N-back performance was not related to BRIEF-WM.

CONCLUSIONS

Our results provide evidence for reliability of N-back accuracy during fMRI scanning; however, reliability of reaction time data is affected by order of task presentation. Data regarding construct validity are inconsistent and emphasize the need to consider clinical utility of behavioral measures in the design and interpretation of functional neuroimaging studies.

Cognitive disorders in pediatric medulloblastoma: what neuroimaging has to offer

Medulloblastomas are the most common malignant childhood brain tumors arising in the posterior fossa. Treatment improvements for these tumors have meant that there are a greater number of survivors, but this long-term patient survival has increased the awareness of resulting neurocognitive deficits. Impairments in attention, memory, executive functions, and intelligence quotient demonstrate that the cerebellum likely plays a significant role in numerous higher cognitive functions such as language, cognitive, and emotional functions. In addition, children with medulloblastoma not only have cerebellar lesions but also brain white matter damages due to radiation and chemotherapy. Functional neuroimaging, a noninvasive method with many advantages, has become the standard tool in clinical and cognitive neuroscience research. By reviewing functional neuroimaging studies, this review aims to clarify the role of the cerebellum in cognitive function and explain more clearly cognitive sequelae due to polytherapy in children with medulloblastoma. This review suggests that the posterior cerebellar lobes are crucial to maintaining cognitive performance. Clinical investigations could help to better assess the involvement of these lobes in cognitive functions.

Emotional distress among adult survivors of childhood cancer

PURPOSE

The purposes of this study were to estimate the prevalence of emotional distress in a large cohort of adult survivors of childhood cancer and to evaluate the interrelationship of risk factors including cancer-related late effects.

METHODS

Adult survivors of childhood cancer (N = 1,863), median age of 32 years at follow-up, completed comprehensive medical evaluations. Clinically relevant emotional distress was assessed using the Brief Symptom Inventory 18 and was defined as T-scores ≥63. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable logistic regression models to identify risk factors for distress. Path analysis was used to examine associations among identified risk factors.

RESULTS

Elevated global distress was reported by 15.1% of survivors. Cancer-related pain was associated with elevated distress (OR 8.72; 95% CI, 5.32-14.31). Survivors who reported moderate learning or memory problems were more likely to have elevated distress than survivors who reported no learning or memory problems (OR 3.27; 95% CI, 2.17-4.93). Path analysis implied that cancer-related pain has a direct effect on distress symptoms and an indirect effect through socioeconomic status and learning or memory problems. Similar results were observed for learning or memory problems.

CONCLUSIONS

Childhood cancer-related morbidities including pain and learning or memory problems appear to be directly and indirectly associated with elevated distress symptoms decades after treatment. Understanding these associations may help inform intervention targets for survivors of childhood cancer experiencing symptoms of distress.

IMPLICATIONS FOR CANCER SURVIVORS

A subset of long-term childhood cancer survivors experience significant emotional distress. Physical and cognitive late effects may contribute to these symptoms.