Processing speed in children treated for brain tumors: effects of radiation therapy and age

How Cancer Harms the Developing Brain: Long-Term Outcomes in Pediatric Cancer Survivors

Survival rates for pediatric cancer are improving, resulting in a rising need to understand and address long-term sequelae. In this narrative review, we summarize the effects of cancer and its treatment on the developing brain, with a focus on neurocognitive function in leukemia and pediatric brain tumor survivors. We then discuss possible mechanisms of brain injury and management considerations.

Neurocognitive development after pediatric brain tumor - a longitudinal, retrospective cohort study

Survivors of Pediatric Brain Tumors (PBTs) treated with cranial radiation therapy (CRT) often experience a decline in neurocognitive test scores. Less is known about the neurocognitive development of non-irradiated survivors of PBTs. The aim of this study was to statistically model neurocognitive development after PBT in both irradiated and non-irradiated survivors and to find clinical variables associated with the rate of decline in neurocognitive scores. A total of 151 survivors were included in the study. Inclusion criteria: Diagnosis of PBT between 2001 and 2013 or earlier diagnosis of PBT and turning 18 years of age between 2006 and 2013. Exclusion criteria: Death within a year from diagnosis, neurocutaneous syndromes, severe intellectual disability. Clinical neurocognitive data were collected retrospectively from medical records. Multilevel linear modeling was used to evaluate the rate of decline in neurocognitive measures and factors associated with the same. A decline was found in most measures for both irradiated and non-irradiated survivors. Ventriculo-peritoneal (VP) shunting and treatment with whole-brain radiation therapy (WBRT) were associated with a faster decline in neurocognitive scores. Male sex and supratentorial lateral tumor were associated with lower scores. Verbal learning measures were either stable or improving. Survivors of PBTs show a pattern of decline in neurocognitive scores irrespective of treatment received, which suggests the need for routine screening for neurocognitive rehabilitation. However, survivors treated with WBRT and/or a VP shunt declined at a faster rate and appear to be at the highest risk of negative neurocognitive outcomes and to have the greatest need for neurocognitive rehabilitation.

Sluggish cognitive tempo profiles in survivors of childhood cancer as compared to children with attention-deficit/hyperactivity disorder

PURPOSE

Neurocognitive late effects including problems with attention have been reported in pediatric oncology survivors. While some researchers have characterized these late effects as similar to symptoms of attention-deficit/hyperactivity disorder, inattentive presentation (ADHD-I), there remains some controversy as to whether these concerns in oncology patients are best conceptualized according to an ADHD-I or sluggish cognitive tempo (SCT) framework. The aim of this study was to describe SCT symptoms in children with ADHD-I or oncology diagnoses; identify groups of SCT symptoms among children with brain tumors (BT), acute lymphoblastic leukemia (ALL), or ADHD-I; and identify whether specific SCT profiles are associated with these diagnoses.

METHODS

The sample was comprised of 364 youth (146 BT, 149 ADHD-I, 69 ALL) referred for a neuropsychological evaluation at an academic medical center. Caregivers completed the SCT scale as part of the clinical evaluation.

RESULTS

Groups differed on mean scores for the SCT scales (Total, Sleepy/sluggish, Low initiation, and Daydreamy) by diagnosis (all p < 0.05), with the ADHD-I group having higher SCT symptoms on all scales. Latent profile analysis showed significant differences between latent SCT classes according to ADHD-I versus cancer diagnosis. The ADHD-I group was significantly more likely to be in the high SCT class compared to the oncology groups.

CONCLUSION

Findings add to the understanding of SCT symptoms in pediatric oncology survivors. There is utility in applying the SCT framework to the oncology population; however, pediatric survivors are likely to be rated differently than youth with ADHD-I. Implications and future directions are discussed.

Processing Speed and Time since Diagnosis Predict Adaptive Functioning Measured with WeeFIM in Pediatric Brain Tumor Survivors

Simple Summary

Brain tumor (BT) survivors show difficulties in adaptive functioning (AF) and in acquiring independence (e.g., graduating, finding employment, building strong relationships, and being independent). The aim of our observational retrospective study is to explore the contribution of different clinical and cognitive variables in explaining and predicting the AF outcomes of BT survivors, measured with the Functional Independence Measure for Children (WeeFIM). The analysis demonstrated that processing speed and time since diagnosis are the main explanatory variables. Other clinical factors, such as age at diagnosis and hydrocephalus, differentially influence functional skills according to distinct domains (i.e., self-care, mobility, and cognition). The identification of the clinical factors influencing AF could suggest targets on which to focus attention. By successfully assessing, understanding, and managing AF, it will be possible to improve its management in pediatric BT survivors.

Abstract

(1) Background: Brain tumor (BT) survivors show difficulties in the acquisition of developmental milestones, related to academic achievement, vocational employment, social relationships, and autonomy. The skills underlying adaptive functioning (AF) are usually damaged in BT survivors due to the presence of the brain tumor, treatment-related factors, and other neurological sequelae. In this study, we aimed to explore the contribution of different cognitive factors in children with BT to AF, considering diagnosis-related variables. (2) Methods: Standardized cognitive assessment was undertaken and clinical information was collected from a retrospective cohort of 78 children with a BT, aged between 6 and 18 year old at the time of the assessment. Regression models were computed to investigate the influence of the selected variables on daily functional skills as measured by the Functional Independence Measure for Children (WeeFIM). (3) Results: The analyses showed that the main explanatory variables are processing speed and time since diagnosis. Other clinical variables, such as age at diagnosis and hydrocephalus, differentially influence functional skills according to distinct domains (i.e., self-care, mobility, and cognition). (4) Conclusions: The main explanatory variables of AF that emerged in our models point to a potential target of improving AF management in pediatric BT survivors.

Effect Evaluation of Combined Application of Magnetic Resonance Diffusion Tensor Imaging and Brain Function Imaging in Radiation Therapy of Brain Tumours Involving Motor Pathways

This study is an attempt to find a way for functional imaging information to be applied clinically in radiation therapy. The basal nucleus is a collective term for a group of neural nucleus in the central nervous system that connects the pontine, brainstem, and cerebral cortex, including the caudate nucleus, the bean-shaped nucleus, the screen-shaped nucleus, and the amygdala. It is difficult to find the exact position of these neural nuclei on the computed tomography (CT) image or the T1 or T2 sequence of magnetic resonance. However, the development of neurosurgery has partially confirmed that these functional nuclei are involved in advanced cognitive functions such as memory, emotion, and learning. Neurosurgery has tried to avoid damaging these nucleus groups during surgery to improve the quality of life of patients, and there is currently no clear strategy for this in radiotherapy. Because CT and magnetic resonance spin echo (SE) sequences are difficult to find the anatomical location of the nucleus, it is difficult to have any strategy to protect these functions in radiotherapy planning. This article uses diffusion tensor imaging (DTI) images and fiber bundle tracking to obtain a more accurate anatomical position of the nerve nucleus on the image, and provides some available strategies for radiotherapy to protect patients’ brain function. The conclusion of this paper is that the combined application of DTI and functional magnetic resonance imaging (fMRI) can better observe the relationship among tumours, functional areas and white matter fibers, and guide the designation of radiotherapy plans.

Microstructural Injury to Corpus Callosum and Intrahemispheric White Matter Tracts Correlate With Attention and Processing Speed Decline After Brain Radiation

PURPOSE

The corpus callosum (CC) and intrahemispheric white matter tracts (IHWM) subserve critical aspects of attention and processing speed. We analyzed imaging biomarkers of microstructural injury within these regions and association with attention and processing speed performance before and after radiation therapy in primary brain tumor patients.

METHODS AND MATERIALS

In a prospective clinical trial, 44 primary brain tumor patients underwent cognitive testing and magnetic resonance imaging/diffusion-weighted imaging at baseline (pre-radiation therapy) and 3-, 6-, and 12-months post-radiation therapy. CC (subregions, total) and IHWM tracts (left/right without CC, total) were autosegmented; tumor, tumor bed, and edema were censored. Biomarkers included volume changes (cm³), mean diffusivity ([MD]; higher values indicate white matter injury), fractional anisotropy ([FA]; lower values indicate white matter injury). Reliable-change indices measured changes in attention (Weschler Adult Intelligence Scale [WAIS-IV] digits-forward; Delis-Kaplan Executive Function System Trail Making [D-KEFS-TM] visual-scanning), and processing speed (WAIS-IV coding; D-KEFS-TM number-sequencing, letter-sequencing), accounting for practice effects. Linear mixed-effects models evaluated associations between mean radiation dose and biomarkers (volume, MD, FA) and imaging biomarkers and neurocognitive performance. Statistics were corrected for multiple comparisons.

RESULTS

Processing speed declined at 6 months following radiation therapy (number sequencing, letter sequencing; P < .04). Seizures and antiepileptic drug therapy were associated with lower visual-scanning attention reliable-change indices at 6 months (P = .039). Higher radiation dose correlated with smaller midanterior CC volume (P = .023); lower FA in posterior CC, anterior CC, and total CC (all P < .03); and higher MD in anterior CC (P = .012). Smaller midanterior CC and left IHWM volume correlated with worse processing speed (coding, letter-sequencing, number-sequencing; all P < .03). Higher FA in right, left, and total IHWM correlated with better coding scores (all P < .01). Lower FA in total IHWM (P = .009) was associated with worse visual-scanning attention scores. Higher FA in midposterior CC (P = .029) correlated with better digits-forward attention scores.

CONCLUSIONS

The CC demonstrated radiation dose-dependent atrophy and WM injury. Microstructural injury within the CC and IHWM was associated with attention and processing speed decline after radiation therapy. These areas represent possible avoidance regions for preservation of attention and processing speed.

The Effects of Radiation and Sex Differences on Adaptive Functioning in Adult Survivors of Pediatric Posterior Fossa Brain Tumors

OBJECTIVE

Radiation therapy (RT) improves rates of survival of patients with childhood brain tumors but increases deficits in cognition and independent living skills. Previous literature has studied difficulties in basic cognitive processes, but few explore impairment in higher-order skills such as adaptive functioning. Some studies identify females as at risk for cognitive deficits due to RT, but few investigate sex differences in adaptive functioning. It was hypothesized that females would exhibit poorer long-term independent living skills and core cognitive skills relative to males following RT.

METHODS

Forty-five adult survivors of posterior fossa childhood brain tumors (24 females) completed the Wechsler Abbreviated Scale of Intelligence (WASI-II), Wechsler Memory Scale, Third Edition (WMS-III) Digit Span Forward (DSF) and Backward (DSB), and Oral Symbol Digit Modalities Test (OSDMT). Informants completed the Scales of Independent Behavior-Revised (SIB-R).

RESULTS

DSF and OSDMT were positively correlated with all five SIB-R domains, full-scale IQ (FSIQ) was positively correlated with four SIB-R domains, and DSB was positively correlated with three SIB-R domains. There was an interaction between sex and RT for OSDMT and community living skills with trend level interactions for personal living skills and broad independent living skills, where females without RT had higher scores than females with RT.

CONCLUSIONS

Female survivors were more affected by RT than males across the community living skills domain of adaptive functioning as well as processing speed. Processing speed deficits may have a cascading impact on daily living skills. Future studies should investigate how clinical and biological factors may contribute to personalized treatment plans between sexes. (JINS, 2019, 25, 729-739).