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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2013  |  Volume : 24  |  Issue : 1  |  Page : 67-71
Assessing the intelligence of children with chronic kidney diseases

1 Department of Psychiatry, Faculty of Medicine, Mansoura University, Mansoura, Egypt
2 Department of Family and Community Medicine, Faculty of Medicine, Mansoura University, Mansoura, Egypt
3 Department of Pediatrics, Faculty of Medicine, Mansoura University, Mansoura, Egypt

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Date of Web Publication22-Jan-2013


To evaluate the level of intelligence in children with chronic kidney diseases (CKDs), 12 children with CKD stage 5 on regular hemodialysis, 12 children in the predialysis stage, and 12 as controls were assessed using the Wechsler Intelligence Scale for Children (WISC). Mean scores on the verbal, performance, and full scale IQ were significantly lower in the predialysis and dialysis children than in the healthy children, while the mean score on the arithmetic subtests was significantly lower in the predialysis children than in the dialysis group. In conclusion, a better understanding of the neurocognitive function in children with CKDs is a critical element to be ascertained early with proper assessment programs so as to design appropriate educational interventions for this handicapping illness.

How to cite this article:
Amr M, El-Gilany AH, Bakr A, El Sheshtawy E. Assessing the intelligence of children with chronic kidney diseases. Saudi J Kidney Dis Transpl 2013;24:67-71

How to cite this URL:
Amr M, El-Gilany AH, Bakr A, El Sheshtawy E. Assessing the intelligence of children with chronic kidney diseases. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2021 Dec 8];24:67-71. Available from: https://www.sjkdt.org/text.asp?2013/24/1/67/106244

   Introduction Top

Chronic kidney disease (CKD) is defined as slow and progressive deterioration of kidney function that is typically irreversible. [1] It is used to describe the whole continuum of progressive kidney disease ranging from chronic renal insufficiency (CRI) to end-stage renal disease (ESRD). The severity of CKD is defined by a decrement in glomerular filtration rate persisting for three or more months. [2] Similar to children with other chronic progressive illnesses, the cross-sectional studies of children with CKD suggest that there is increased risk for a wide range of delays in motor and cognitive development, particularly for children with ESRD. [3],[4],[5],[6],[7] Most studies have demonstrated lower intelligent quotient (IQ) scores among children with ESRD than in unaffected siblings or the general population, [7],[8],[9] and also when comparing pre- and post-transplantation performances. [6] Memory deficits also have been identified in children with mild CKD as well as ESRD. [3] Most of these studies were done in Western countries, with only few studies conducted in the developing world. The lack of research on psychological morbidity in developing countries has led to a gap in assessing the global burden of disease. [10] Bakr et al [11] found that adjustment disorders were the most common disorders (18.4%) among children with ERSD on regular hemodialysis, followed by depression (10.3%) and neurocognitive disorders (7.7%), In Egypt, as in many developing countries, the focus of health care is on medical problems of the adults and rarely they address the social and psychological needs of adolescents, especially those with chronic illness like CKDs. The present study examines the intelligence level in a sample of Egyptian children with CKD compared to healthy controls.

   Materials and Methods Top

CKD patients were recruited consecutively from those attending the pediatric nephrology unit, Mansoura University Children's hospital. Twenty-four children with CKD and 12 children as controls, between the ages of ten years and 15 years, were enrolled in the study. None of the 24 CKD patients had undergone kidney transplantation. Of these patients, 12 had CKD stage 5 and were on regular hemodialysis (dialysis group) and 12 had predialysis CKD (pre-dialysis group). The underlying diseases were urological abnormalities and glomerulonephritis in 45.8% and 20.8% of them, respectively. Others causes included unknown (16.7%), pyelonephritis (8.3%), and more than one cause (8.3%). CKD was diagnosed when the creatinine clearance (Crcl) (measured by the Schwartz formula) was <90 mL/min per 1.73 m 2 body surface area (BSA). The pre-dialysis group included one child with CKD stage 2, six children with stage 3, and five children had stage 4.

Patients were started on dialysis when their Crcl was <15 mL/min per 1.73 m 2 BSA. The children were dialysed for 4 h three times weekly with proper efficient dialysis as evident by KT/V value more than 1.2%. All patients were taking calcium-based phosphate binders, calcitriol, and iron, orally, erythropoietin subcutaneously, and antacids. The dialysis group comprised 11 children who did not attend a regular classroom and one child used to attend a vocational rehabilitation school. However, of those on predialysis, nine attended regular classes in school and the remaining three attended the schools only at the time of examinations.

The comparison group of control children was recruited from children who attended the outpatient clinic for mild illnesses (e.g. respiratory tract infections). None of them had evidence of chronic physical illnesses. After informed consent from the parents had been obtained, social score was used to evaluate the socioeconomic status of the children's families. The total score of 30 encompasses parental education and work, family size, monthly per capita, and numbers of rooms in the house. [12] The Arabic version of the Wechsler Intelligence Scale for Children (WISC) [13] was used according to the standard procedure and as the standard measurement of general intelligence. The same experienced psychologist, who was unaware of the details of the medical history, conducted the WISC assessment for each patient. Patients on chronic hemodialysis performed the test at least one day after a hemodialysis session. The WISC consists of 11 subtests: six subtests of verbal intelligence (information, comprehension, arithmetic, similarities, digit span, and vocabulary) and five subtests of nonverbal, performance intelligence (coding, picture completion, block design, picture arrangement, and object assembly). Scores derived from these subtests include the full scale IQ, verbal IQ, and performance IQ. The patients did not complete all the subtests in the WISC (vocabulary and picture arrangement subtests), so their IQ scores were calculated from the available data.

   Statistical Analysis Top

Data were analyzed using the Statistical Package for Social Sciences (SPSS) version 11. Chi-square test was used for comparison between groups. Quantitative variables were tested for normality distribution by Kolomogorov-Smirnov test. The variables were presented as mean ± SD. In normally distributed variables, analysis of variance (ANOVA) with Bonferroni multiple comparisons test was used for comparison between CKD and control groups. A P value of ≤0.05 was considered to be statistically significant.

   Results Top

[Table 1] shows that the serum albumin and hemoglobin were considerably more compromised in the dialysis patients than in either the predialysis group or healthy children. The median duration of dialysis was 16 months and the median KT/V (a ratio used to quantify hemodialysis treatment adequacy) was 1.1. Hypertension was reported in seven children (58.3%) of predialysis group and four children (33.3%) of dialysis group.
Table 1: Socio-demographic and clinical characteristics of the sample.

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Analysis of the WISC tests [Table 2] showed that the mean scores on the verbal, performance, and full scale IQ were significantly lower in the predialysis and dialysis children than in the healthy children. In comparison, only the mean score on the arithmetic subtest was significantly lower in the predialysis children than in the healthy children.
Table 2. Cognitive assessment of the sample.

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   Discussion Top

This study examined the current neurocognitive profile of children with CKD who were either on conservative treatment or on dialysis, and compared these with healthy children. Chronic renal failure has been shown to be associated with deficits in neurocognitive performances with the potential to limit cognitive development and long-term educational attainment. [14]

An initial inspection of the WISC scores showed that the sample of children with CKDs was variable, with most of the participants falling within the borderline to average range on most tasks, compared to the average range in the healthy controls.

The mean scores on verbal, performance, and the full scale IQ were significantly lower in the predialysis and dialysis children than in the healthy children; the full scale IQ was significantly lower in the dialysis children than in the predialysis children. This supports previous studies that have documented lower IQ scores among children with CKD compared with healthy children. [7],[8],[9],[15],[16] It has been found that children with renal disease in all stages of therapy (predialysis, dialysis, and transplant) performed worse than controls on a series of neuropsychological tests and this difference became more marked over time. [5] This effect does not appear to fluctuate directly with the changes in serum urea nitrogen, as study of children before and after hemodialysis sessions did not demonstrate improvement in performance on measures of attention, problem solving, and paired associate learning after hemodialysis. [17]

In this study, dialysis was adequate in our subjects as determined by measured Kt/V and none of them was inadequately dialyzed. This raises the possibility that even the most intensive dialysis regimens would fail to correct deficits in neurocognitive function. [18]

Analysis of the WISC results showed lowered scoring on the arithmetic subtest of verbal intelligence in predialysis children. As the condition progressed, the dialysis-dependent children showed more deficits in the subtests of language (comprehension), mental processing speed, and sustained attention (arithmetic), in addition to the subtests of visual perceptual abilities, such as block design, picture completion, and coding subtests. This was in accordance with previous studies. It has been reported that neuropsychological functioning in renal failure has consistently shown deficits of mental efficiency, psychomotor speed, and attention in affected patients. [14],[19] Deficits in visual perceptual abilities, abstraction abilities, and sustained attention skills were documented in children with CKD. [4],[5] Symptoms such as apathy, irritability, somnolence, distractibility, restlessness, diminished attention span, impaired memory, and difficulties in visual-motor co-ordination and nonverbal abstraction have been described in advanced uremia. [20] Although the exact mechanism by which renal failure affects the neurocognitive function is not clear, Valanne et al [21] reported that 18 of 33 (54%) children with congenital nephrotic syndrome exhibited magnetic resonance imaging (MRI) findings of chronic infarct lesions, mostly within the periventricular white matter. Furthermore, Elzouki et al [22] identified unspecified EEG abnormalities in six of 14 (42%) patients with CKD. Hurkx et al [23] suggested the possibility of delayed myelination or synaptogenesis of the somatosensory cortex in young children with CKD, regardless of renal replacement therapy.

Our study has a few limitations. At the time of our data collection, the revised version of the WISC (WISC-IV) was not available in Egypt. Another limitation is related to the small size of the sample, and our patients therefore may not be representative of all children with CKD. This potentially limits the generalization of the current findings. Further studies with large number of patients from many medical facilities are recommended, so that these results can be generalized.

In conclusion, the mean scores on the verbal, performance, and full scale IQ were significantly lower in the predialysis and dialysis children than in the healthy children, while the mean score on the arithmetic subtest was significantly lower in the pre-dialysis children than in the dialysis group. These findings have important implications that contribute in understanding the neurocognitive function in children with CKD. The clinicians must make sure that some agency advises the families and provides an early assessment program. This will contribute and help in designing appropriate developmental interventions and educational support for this handicapped condition.

   References Top

1.Gerson AC, Butler R, Moxy-Mims M, et al. Neurocognitive outcomes in children with chronic kidney disease: Current findings and contemporary endeavors. Ment Retard Dev Disabil Res Rev 2006;12:208-15.   Back to cited text no. 1
2.Hogg RJ, Furth S, Lemley KV, et al. National Kidney Foundation's Kidney Disease Outcomes Quality Initiative clinical practice guidelines for chronic kidney disease in children and adolescents: Evaluation, classification, and stratification. Pediatrics 2003;111:1416-21.  Back to cited text no. 2
3.Fennell RS, Fennell EB, Carter RL, Mings EL, Klausner AB, Hurst JR. Correlations between performances on neuropsychological tests in children with chronic renal failure. Child Nephrol Urol 1990;10:199-204.   Back to cited text no. 3
4.Fennell RS, Fennell EB, Carter RL, Mings EL, Klausner AB, Hurst JR. Association between renal function and cognition in childhood chronic renal failure. Pediatr Nephrol 1990;4:16-20.  Back to cited text no. 4
5.Fennell RS, Fennell EB, Carter RL, Mings EL, Klausner AB, Hurst JR. A longitudinal study of the cognitive function of children with renal failure. Pediatr Nephrol 1990;4:11-5.   Back to cited text no. 5
6.Mendley SR, Zelko FA. Improvement in specific aspects of neurocognitive performance in children after renal transplantation. Kidney Int 1999;56:318-23.   Back to cited text no. 6
7.Brouhard BH, Donaldson LA, Lawry KW, et al. Cognitive functioning in children on dialysis and posttransplantation. Pediatr Transplant 2000;4:261-7.  Back to cited text no. 7
8.Madden SJ, Ledermann SE, Guerrero-Blanco M, Bruce M, Trompeter RS. Cognitive and psychosocial outcome of infants dialyzed in infancy. Child Care Health and Dev 2003;29: 55-61.  Back to cited text no. 8
9.Qvist E, Pihko H, Fagerudd P, et al. Neuro-developmental outcome in high-risk patients after renal transplantation in early childhood. Pediatr Transplant 2002;6:53-62.  Back to cited text no. 9
10.Global Forum for Health Research. The 10/90 Report on Health Research. Geneva: Global Forum for Health Research; 2000.  Back to cited text no. 10
11.Bakr A, Amr M, Sarhan A, et al. Psychiatric disorders in children with chronic renal failure. Pediatr Nephrol 2007;22:128-31.  Back to cited text no. 11
12.Fahmy SI, El-Sherbini AF. Determining simple for social classifications for health research. Bull High Inst Public Health 1983;13:95-108.  Back to cited text no. 12
13.Melika L, Dar El-Nahda El-Masryia. Wechsler Intelligence Scale for Children - Arabic version. Cairo, 1984.   Back to cited text no. 13
14.Baron IS, Fennell EB, Voeller KK. Renal disease. In: Pediatric Neuropsychology in the Medical Setting. New York: Oxford University Press; 1995. p. 370-83.   Back to cited text no. 14
15.Al-Menabbawy KH, Nassef Y, Ibraheim AM. Nutritional status and neurobehavioral changes among children with chronic renal failure. Egypt Med J NRC 2003;2:113-28.   Back to cited text no. 15
16.Bawden HN, Acott P, Carter J, et al. Neuropsychological functioning in end-stage renal disease. Arch Dis Child 2004;89:466-76.   Back to cited text no. 16
17.Rasbury WC, Fennell RS, Eastman BG, Garin EH, Richards G. Cognitive performance in children with renal disease. Psychol Rep 1979; 45:231-9.   Back to cited text no. 17
18.Slickers J, Duquette P, Hooper S, Gipson D. Clinical predictors of neurocognitive deficits in children with chronic kidney disease. Pediatr Nephrol 2007;22:565-72.  Back to cited text no. 18
19.Hart RP, Kreutzer JS. Renal system. In: Tarter RE, Van Thiel D, Edwards KL, eds. Medical Neuropsychology: The Impact of Disease on Behavior. New York: Plenum; 1988. p. 99-120.  Back to cited text no. 19
20.Teschan PE. Measurement of neurobehavioral responses to renal failure, dialysis and transplantation In: Levy NB, ed. Psychonephrology. New York: Plenum Press; 1981. p. 13.  Back to cited text no. 20
21.Valanne L, Qvist E, Jalanko H, Holmberg C, Pihko H. Neuroradiologic findings in children with renal transplantation under 5 years of age. Pediatr Transplant 2004;8:44-51.   Back to cited text no. 21
22.Elzouki A, Carroll J, Butinar D, Moosa A. Improved neurological outcome in children with chronic renal disease from infancy. Pediatr Nephrol 1994;8:205-10.  Back to cited text no. 22
23.Hurkx W, Hulstijn-Dirkmaat I, Pasman J, Rotteveel J, Visco Y, Schröder C. Evoked potentials in children with chronic renal failure, treated conservatively or by continuous ambulatory peritoneal dialysis. Pediatr Nephrol 1995;9:325-8.  Back to cited text no. 23

Correspondence Address:
Mostafa Amr
Department of Neuroscience, College of Medicine in Al-Ahsa, King Faisal University, Al Ahsa, Saudi Arabia

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DOI: 10.4103/1319-2442.106244

PMID: 23354194

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