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a Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina
b Department of Pediatrics, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| ABSTRACT |
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METHODS. Thirty-five HIV-infected, 35 HIV-affected, and 90 control children aged 18 to 72 months were assessed by using the Bayley Scales of Infant Development II, Peabody Developmental Motor Scales, Snijders-Oomen Nonverbal Intelligence Test, and Rossetti Infant-Toddler Language Scale, as appropriate for age.
RESULTS. Overall, 60% of HIV-infected children had severe delay in cognitive function, 29% had severe delay in motor skills, 85% had delays in language expression, and 77% had delays in language comprehension, all significantly higher rates as compared with control children. Young HIV-infected children (aged 18–29 months) performed worse, with 91% and 82% demonstrating severe mental and motor delay, respectively, compared with 46% and 4% in older HIV-infected children (aged 30–72 months). HIV-affected children had significantly more motor and language expression delay than control children.
CONCLUSIONS. The impact of the HIV pandemic on children's neurodevelopment extends beyond the direct effect of the HIV virus on the central nervous system. AIDS orphans and HIV-negative children whose mothers had AIDS demonstrated significant delays in their neurodevelopment, although to a lesser degree and in fewer developmental domains than HIV-infected children. Young HIV-infected children were the most severely afflicted group, indicating the need for early interventions. Older children performed better as a result of a "survival effect," with only those children with less aggressive disease surviving.
Key Words: HIV AIDS neurodevelopment child Africa
Abbreviations: HAART—highly active antiretroviral treatment DRC—Democratic Republic of Congo CNS—central nervous system SON—Snijders-Oomen Nonverbal
The HIV/AIDS epidemic continues to affect millions of children in developing countries, because access to prevention of mother-to-child transmission interventions and highly active antiretroviral treatment (HAART) have not yet reached wide coverage in many high HIV prevalence countries. At the end of 2006, an estimated 2.3 million children were living with HIV/AIDS and 530000 were newly infected with HIV in 2006. The Democratic Republic of Congo (DRC) is home to an estimated 120000 children living with HIV and 680000 AIDS orphans.1
Since the first reports of pediatric AIDS in the 1980s, delayed neurodevelopment has been a well-recognized complication of HIV disease.2,3 Experiences from the United States and Europe indicate that HIV central nervous system (CNS) involvement can occur before there is significant immunosuppression and may be the first AIDS-defining illness in as many as 18% of pediatric patients.4,5 HIV-related encephalopathy can present as static or progressive HIV encephalopathy, with microcephaly, delay or loss of developmental milestones (motor, mental and language), and pyramidal tract symptoms.6 Before HAART was introduced, encephalopathy was reported in 35% to 50% of children with a diagnosis of AIDS in the United States.5,7–10 HAART can prevent and reverse encephalopathy present at the time of HAART initiation.11,12 Consequently, the introduction of HAART in the United States has reduced the incidence of encephalopathy to <2%.11
Results from studies in the United States and Europe may not be generalizable to the population in Africa and other resource-poor settings, where there is also a high prevalence of malnutrition, malaria, tuberculosis and other opportunistic infections, and substantially different child-rearing environments. Despite that sub-Saharan Africa is home to 80% of HIV-infected children, there is a paucity of data on neurodevelopment from this region. Results of the few studies demonstrated HIV-related CNS involvement at similar or higher prevalence rates compared with the United States. A study of Rwandan children 6 months to 2 years of age observed that 40% of HIV-infected children had an abnormal neurodevelopmental examination at 18 months compared with only 5% of HIV-exposed uninfected children, and gross motor scores were significantly lower at all studied time points in HIV-infected children.13 A study in the DRC documented developmental impairment in both asymptomatic HIV-infected children and HIV-exposed, uninfected children compared with control children, supporting the idea that there may be an environmental component compounding the delay as a result of the presence of HIV in the CNS.14 A study of Ugandan children from birth to 2 years found that HIV-infected infants not only scored lower in mental and motor development but also demonstrated greater deceleration in their rate of motor development compared with HIV-exposed, uninfected infants and a control group.15 At school age (6–12 years), these HIV-infected children experienced poorer growth and more acute illness but were not significantly different in their neurologic, motor, and psychometric development compared with control children, suggesting that children with more aggressive encephalopathy may not survive to school age in the absence of HAART.16 A study of children in Tanzania found that the developmental scores decreased with increasing age, suggesting a cumulative risk for poor neurodevelopment caused by HIV, poverty, and the stress placed on families who care for HIV-infected individuals.17 This study aimed to examine the effects of the HIV epidemic on the cognitive, motor, and language development of preschool-aged children in Kinshasa, capital of the DRC.
| METHODS |
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Data Collection
Clinical and anthropometric data, socioeconomic status, and health status of the parents were collected at enrollment. Socioeconomic status was assessed by inquiring about access to running water, number of bedrooms, income, type of toilet, adequacy of income, and food.
For younger children (aged 18–29 months), the Bayley Scales of Infant Development, 2nd Edition, was used to assess mental (Mental Development Index) and motor development (Psychomotor Development Index), and the Rossetti Infant-Toddler Language scale (1990 version) was used to evaluate language development. Older children (aged 30–72 months were assessed using the Peabody Developmental Motor Scales (2nd edition), the Snijders-Oomen Nonverbal (SON) Intelligence test 2
–7 (abridged 2004 version including situations, mosaics, categories, and patterns), and the Rossetti Infant-Toddler Language scale for children up to 36 months of age. Language development was not assessed for children who were older than 36 months. Assessment tools were translated into Lingala, the local language.
Neurodevelopmental assessment was performed by 1 pediatrician and 2 physiotherapists, who had received an 8-week neurodevelopmental assessment training (Bayley, Rossetti) in Cape Town, South Africa. In addition, the pediatrician (Dr Mupuala) had received training that consisted of 108 hours in neurodevelopmental testing procedures (Bayley, Peabody, and SON), 140 hours of neuropediatric consultations, and 72 hours of consultations at care institutions for children with neurodevelopmental disorders in Leuven, Belgium.
Data Analyses
Group means were calculated for the norm-referenced Bayley Scales of Infant Development-II, Peabody, and SON. The neurodevelopment of children was classified as "no delay" when their score fell within 1 SD of the mean standardized score, (100) "moderate delay" when they scored between 1 and 2 SDs from the mean (ie, 70–84), or "severe delay" when they score <2 SDs (
69). For the Rossetti test, we computed a global baseline and ceiling age level (ie, the oldest 3-month age level at which the child mastered all items in language expression and language comprehension). Children were considered to have "no delay" when their score fell within their 3-month age category or when they scored in the 3-month age category below their age. They were considered "delayed" in their language development when they scored
2 3-month categories below their age.
Group means were compared by using t tests or the nonparametric Wilcoxon ranked-sum tests. The
2 test for contingency tables and Fisher's exact tests compared categorical and event frequency data. Analysis was conducted by using SAS 8.2 (SAS Institute, Inc, Cary, NC).
| RESULTS |
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Both moderate (26.7%) and severe (24.4%) delay in mental development was observed, and mental delay was more frequent in older children. In contrast, severe motor delay was not observed among control children, and moderate motor delay was present in 7.8% and was more frequent among young children (aged 18–29 months) than older children (30–72 months), with 25% and 2.9% moderate motor delay, respectively (Table 2). Among the children tested for language development (aged 18–36 months), delay in language comprehension and language expression was found in 12.9% (Table 3).
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Motor Developmental in HIV-Infected and HIV-Affected Children
Severe delay in motor development was observed in 28.6% of HIV-infected and 14.3% of HIV-affected children, and moderate delay was present in 40% of HIV-infected and 14.3% of HIV-affected children (Table 2). Motor delay was more prevalent among younger children (aged 18–29 months), with 81.8% of HIV-infected and 38.5% of HIV-affected young children presenting with severe delay, compared with only 4% of older HIV-infected and 0% of HIV-affected children.
Language
HIV-infected children 18 to 36 months of age demonstrated significantly higher rates of delay in language expression (84.6%) and language comprehension (76.7%) compared with control children (P < .0001). Language expression but not language comprehension was delayed in the HIV-affected children compared with the control children (P < .02; Table 3).
| DISCUSSION |
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The frequent delay in neurodevelopment among HIV-infected children was also observed in the previous studies of African HIV-infected children.13–15,18 Comparison of results between studies is difficult because of differences in age groups studied and the diversity of neuroassessment tools used. Two studies that also used the Bayley scales (versions I and II) observed that, by 18 months of age, severe motor delay was observed among 27% to 30% and severe mental delay in 26% to 27% of HIV-infected children.15,18
In contrast to previous studies,15,19–21 we observed that mental and not motor delay was most severely affected by HIV infection. The high prevalence of delay in cognitive development may in part be attributable to differences in child-rearing practices and lack of exposure to educational toys and multimedia by African children. This is supported by the high frequency (24.4%) of severe delay in mental development among the healthy control children, which is much higher than a 2.2% rate that one would expect if the distribution were similar to that in the reference population.
In this study, the impact of HIV infection on both mental and motor development was most pronounced among the younger children. Although we cannot exclude the effect of using different assessment tools in the 2 age groups, we believe that the observed increased prevalence of delay in the younger HIV-infected group can most likely be attributed to the absence of access to HAART before the start of this study. In the absence of HAART, children with fast progression and more aggressive disease are likely to die before reaching the age of 2.22,23 The older children included in the study may thus represent a group of children with milder disease. A similar "survival effect" was reported from Uganda, where HIV-infected children aged 6 to 12 years were no longer different in their neurodevelopment compared with control children.16
Three other studies also assessed the development of HIV-exposed, uninfected children in sub-Saharan Africa.13–15 Two studies did not observe significant differences between HIV-exposed, uninfected children and control children. In contrast to our study, these children were younger (<2 years of age), and the socioeconomic status and quality of the home environment of HIV-exposed children was not different from that of control children, indicating that the living conditions of these children was not substantially affected by HIV. In the remaining study, HIV-exposed, uninfected children who were aged
2 years had a significantly poorer performance on global cognitive measures but comparable motor performance.14 No data were presented on the living conditions of these children. In our study, in which children affected by AIDS in the family were selected, we observed higher frequencies of poor motor, mental, and language expression development among HIV-affected, seronegative children. The data suggest that AIDS in the family may lead to poverty, poor health, poor living conditions, and fewer positive parent–child interactions that are conducive to a child's neurodevelopment.
Several limitations to the study should be noted. The sample size was too small to model the impact of covariates and comorbidities using logistic regression. The cross-sectional nature of this study did not allow exclusion of factors that may have had an impact on the child's neurodevelopment before study assessment. Neurologic imaging and standardized classification of neurologic examination were not available. Assessment of the language development was not available for the older children, because we were unable to adapt an existing tool for use in Lingala. Using the classification as normal, moderate, and severe neurodevelopmental delay based on US or European norms may have led to misclassification of children and biased the results to a higher prevalence of mental delay. We chose not to modify the Bayley assessment tools to make the assessment culturally appropriate because we were interested in comparisons between groups and preferred to facilitate comparability between past and future studies in other settings.
| CONCLUSIONS |
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| ACKNOWLEDGMENTS |
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We thank Paul De Cock and Jenifer Jelsma for the training of the study team in neurodevelopmental assessment. We also thank our study team (Nadine Nossa, Iam Zephyrin, Nene Kilese, Vera Melotte, and Kashamuka Mwandagalirwa) for their efforts and the patients and families for participation in the study.
| FOOTNOTES |
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Address correspondence to Annelies Van Rie, MD, PhD, University of North Carolina, Department of Epidemiology, 2104F McGavran Greenberg Hall, Chapel Hill, NC 27599-7435. E-mail: vanrie{at}email.unc.edu
The authors have indicated they have no financial relationships relevant to this article to disclose.
| What's Known on This Subject In the United States, HIV encephalopathy occurred in 35% to 50% of children with AIDS before HAART. Results are not generalizable to Africa. Only 6 studies have assessed the effect of HIV on neurodevelopment in Africa, 5 of infants and 1 of school-aged children.
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| What This Study Adds We demonstrate that young HIV-infected children are the most severely affected group, indicating the need for early intervention. Our study is the first to demonstrate that AIDS orphans and children who live with parents with AIDS also experience delayed neurodevelopment.
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