Cognitive Functioning in a Pediatric Population
During the Acute Stage of TBI Recovery
Karen M. Sheridan, Ph.D.
Brad Ross, Ph.D.
Sue Stephens, LCSW, ACSW
Children’s Specialized Hospital, Mountainside, NJ
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Karen M. Sheridan, Ph.D. Dr. Sheridan holds a Ph.D. in Developmental Psychology from Yeshiva University. She conducted doctoral and post-doctoral research at Albert Einstein College of Medicine, utilizing electrophysiological recordings to study cognitive processes. Dr. Sheridan is currently a Postdoctoral Fellow in the department of Psychology and Neuropsychology at Children’s Specialized Hospital, Mountainside NJ, where she works with children who have sustained brain injury as well as other traumas. In addition, she is conducting research examining cognitive functioning during recovery from pediatric brain injury.

Brad Ross, Ph.D. Dr. Brad Ross has worked in the field of pediatric acquired brain injury for over 10 years. He is Coordinator of Neuropsychology and Associate Director of the Brain Injury Program at Children’s Specialized Hospital (CSH) in New Jersey. He also is Assistant Clinical Professor in Psychiatry at Robert Wood Johnson/ UMDNJ Medical School.. Dr. Ross has presented at a number of national and international conferences on topics including the neuropsychological sequellae of pediatric acquired brain injury.

Sue Stephens, LCSW, ACSW Sue Stephens has an MSSW from Columbia University. She is a licensed clinical social worker in New Jersey and holds an ASCW certification from the National Association of Social Workers. Currently, Ms. Stephens is the Coordinator of the Neuro-Rehabilitation Program at Children’s Specialized Hospital and has worked in this program for 11.5 years. She has recently been one of the lead writers for a revision of a caregiver’s guide to school re-entry for students with TBI, She has presented on school re-entry and the use of compensatory strategies at schools and statewide conferences.

INTRODUCTION

Pediatric traumatic brain injury (TBI) is associated with functional sequelae including deficits in overall intelligence, language, attention, memory, and executive functioning as well as behavioral and affective difficulties (see Guthrie et al, 1999 for review). To date, research in the area of pediatric TBI has focused chiefly on the temporal course of recovery within specific areas of functioning (Anderson et al., 1999; Catroppa & Anderson, 2002). However, investigation of long term cognitive recovery across multiple domains of functioning suggest that more persistent deficits exist in areas of performance IQ, adaptive problem solving, and memory when compared to verbal IQ and academics (Jaffe et al., 1995). However, it is not known whether such a pattern of recovery is evident during the acute period of recovery, or if deficits are of a global nature at this earlier time. As rehabilitative services begin shortly after injury, a profile of acute cognitive functioning is necessary for optimal planning of services and specifically, for the planning of a favorable cognitive environment.

To this end, the present study sought to examine whether differences across cognitive domains are evident at the acute phase of recovery and whether differential levels of performance can be detected at this time within cognitive domains. Children’s performance was compared across tasks of overall intelligence, academic skill, learning and memory, and attention with the expectation that learning and memory for new information as well as attention would be more compromised than skills that were acquired prior to the child’s head injury.

METHOD

Participants
Forty two youngsters (32 males) who sustained a moderate to severe TBI between the ages of 6 and 16 years served as participants. The mean age that injury was sustained was 11.6 years (standard deviation = 2.9 years). There was a documented history of learning disability in 11.9% of the participants.

Procedure and Measures
A comprehensive neuropsychological evaluation was conducted with all participants within four months following injury. The following areas of functioning were examined in this study:

Intellectual functioning. The Wechsler Intelligence Scale for Children, 3rd Edition (WISC-III) was administered and Full scale IQ, Verbal IQ, and Performance IQ scores were obtained for all participants. Factor based index scores for Verbal Comprehension, Perceptual Organization, Freedom from Distractibility, and Processing Speed were obtained and analyzed for a sub-set of 25 participants who completed all supplemental sub-tests. Time constraints prohibited the remaining children from completing all supplemental sub-tests and thus, obtaining all four index scores.

Learning and Memory. The California Verbal Learning Test, Children’s Version (CVLT-C) was administered. To assess recall over learning trials, we analyzed participants’ Free Recall score for trial 1, trial 5, and total trials. We examined children’s discriminability score in order to assess recognition.

Academic Achievement. The Wide Range Achievement Test 3rd Edition, Reading (WRAT-R), Spelling (WRAT-S), Arithmetic (WRAT-A) was administered to all participants.

Attention. The Stroop Color-Word Interference task was administered in order to examine performance on a task of competing attention.

Data Analysis
All test scores were transferred to Z-scores in order to compare performance across tests. Performance was compared using paired t-tests and repeated measures Analysis of Variance with Tukey HSD post-hoc analysis. Statistical significance was obtained at p < .05 level. Children’s documented prior learning disability was
controlled for in all analysis.

RESULTS

Functioning Across Cognitive Domains
Figure 1 illustrates that during the first four months following TBI, children’s task performance ranged from .68 to 1.26 standard deviations below the mean. This reflects a level of functioning that ranges from the average to the mildly impaired range. Analysis supported differential performance as a function of cognitive task (F = 4.93, d.f. = 4, p < .001). Post-hoc analysis revealed children’s performance to be comparable within the areas of Verbal IQ, WRAT-spelling, and WRAT-reading. This level of functioning was significantly different from that of Performance IQ, CVLT-C, Stroop Color-Word, and WRAT-arithmetic scores, where performance was within the mildly impaired range.

Functioning Within Cognitive Domains

Intelligence. Analysis of IQ Index Scores revealed that a Processing Speed was significantly more impaired than the performance in the areas of Verbal Comprehension, Perceptual Organization, and Freedom from Distractibility (F = 3.11, d.f. = 3, p < .032) (See figure 2). In fact, children’s performance in the latter three areas did not statistically differ.

Academic performance. As seen in Figure 1, differential performance was observed with respect to children’s academic skill. Performance on the WRAT-arithmetic task was significantly lower than performance on the WRAT-spelling or WRAT-reading tasks. Functional performance was assessed to be within the mildly impaired range on the WRAT-arithmetic task, while an average level of performance was found in both the WRAT-spelling and WRAT-reading tasks.

Learning and Memory. Analysis of children’s CVLT-C performance on Trial 1 and Trial 5 revealed a significant improvement over repeated learning trials (t = 2.97, d.f. = 41, p < .005). However, as seen in Figure 3, the rate of learning over trials is below that which is expected for an age matched, normative population.Comparison of performance for memory encoding and retrieval was conducted by comparing scores of recall for total trials to discriminability scores. Statistical analysis did not support differential performance in these tasks and functioning was within mildly impaired range in both tasks (see Figure 4)

DISCUSSION

The results of this study suggest that for during the acute period of recovery from TBI, children’s cognitive deficits are not global. Indeed, differential levels performance were revealed across cognitive areas, indicating that areas of relative strength and weakness exist early after injury. Relative strength was evident in children’s ability to retrieve and utilize linguistic based information that was learned prior to their injury. Weakness was apparent in cognitive tasks requiring rapid processing and competing attention as well as learning and memory for new information. This is consistent with the findings of Jaffe et al., (1995) who reported differential performance in a group of children of a similar age at three years post injury. The present findings extend previous work by demonstrating that differential functioning is present relatively early in the recovery process.

It was expected that children’s performance on tasks that relied on previously learned information would be less impaired than novel tasks. However, analysis of children’s academic skill did not fully support this hypothesis, as arithmetic performance was more impaired than spelling and reading. It is possible that lower arithmetic scores reflect greater task demands than reading and spelling, such as higher visual organizational and attentional skills.

Despite children’s weakness in learning and memory of new material, performance across a learning trial task revealed that new learning did occur, but at a slowed rate. This suggests although children can represent new information in memory and recall it, the amount of information that they can learn over time is reduced. This may reflect impairment in the ability to apply effective learning strategies, memory capacity, as well as attention. Furthermore, the failure to find a difference between children’s recall and recognition suggests that memory may be more diffusely affected during this early stage of recovery, with deficits in encoding as well as retrieval. Recognition presumably places lesser demands on retrieval, as one is provided with a cue to prompt memory. A free recall task, however, provides no such cue and it relies on a stable representation of information in memory as well as accurate retrieval.

In summary, children recovering from TBI demonstrate several areas of relative cognitive strength early in the recovery process and may rely heavily on previously learned information. An optimal environment for rehabilitative services should be one that attempts to capitalize on a youngster’s cognitive strengths as well as decrease demands on attention, processing speed, and memory for large amounts of new information.

REFERENCES
Anderson, V.A., Cartoppa, C., Morse, S.A., & Haritou, F. (1999). Functional memory skills following traumatic brain injury in young
children. Pediatric Rehabilitation, 3 (4). p. 159 – 166.

Catroppa, C. & Anderson, V.A. (2002). Recovery in memory function in the first year following TBI in children.
Brain Injury, 16 (5). p. 369 – 384.

Guthrie E, Mast J, Richards P, McQuaid M, Pavlakis S. (1999). Traumatic brain injury in children and adolescents.
Child Adolesc. Psychiatr. Clin. N.Am. 8(4). p. 807-826,

Jaffe, K.M., Polissar, N., Fay, G.C., & Liao, S. (1995) Recovery trends over three years following pediatric traumatic brain injury.
Archives Phys. Med. Rehabilitation, 76. p. 17 – 26.

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