The effects of prenatal HIV exposure on language functioning in Kenyan children: establishing an evaluative framework.

BACKGROUND: HIV infection has been associated with impaired language development in prenatally exposed children. Although most of the burden of HIV occurs in sub-Saharan Africa, there have not been any comprehensive studies of HIV exposure on multiple aspects of language development using instruments appropriate for the population. METHODS: We compared language development in children exposed to HIV in utero to community controls (N = 262, 8-30 months) in rural Kenya, using locally adapted and validated communicative development inventories. RESULTS: The mean score of the younger HIV-exposed uninfected infants (8-15 months) was not significantly below that of the controls; however older HIV-exposed uninfected children had significantly poorer language scores, with HIV positive children scoring more poorly than community controls, on several measures. CONCLUSIONS: Our preliminary data indicates that HIV infection is associated with impaired early language development, and that the methodology developed would be responsive to a more detailed investigation of the variability in outcome amongst children exposed to HIV, irrespective of their infection status.

Developmental inventories using illiterate parents as informants: Communicative Development Inventory (CDI) adaptation for two Kenyan languages.

Communicative Development Inventories (CDIs, parent-completed language development checklists) are a helpful tool to assess language in children who are unused to interaction with unfamiliar adults. Generally, CDIs are completed in written form, but in developing country settings parents may have insufficient literacy to complete them alone. We designed CDIs to assess language development in children aged 0;8 to 2;4 in two languages used in Coastal communities in Kenya. Measures of vocabulary, gestures, and grammatical constructions were developed using both interviews with parents from varying backgrounds, and vocabulary as well as grammatical constructions from recordings of children's spontaneous speech. The CDIs were then administered in interview format to over 300 families. Reliability and validity ranged from acceptable to excellent, supporting the use of CDIs when direct language testing is impractical, even when children have multiple caregivers and where respondents have low literacy levels.

Adaptation of Western measures of cognition for assessing 5-year-old semi-urban Ugandan children.

BACKGROUND: The majority of available psychometric tests originates from the Western World and was designed to suit the culture, language, and socio-economic status of the respective populations. Few tests have been validated in the developing world despite the growing interest in examining effects of biological and environmental factors on cognitive functioning of children in this setting. AIMS: The present study aimed at translating and adapting Western measures of working memory, general cognitive ability, attention, executive function, and motor ability in order to obtain a cognitive instrument suitable for assessing 5-year-old semi-urban Ugandan children. This population represents a particular assessment challenge as school enrolment is highly variable at this age in this setting and many children are unused to a formal educational setting. METHODS: Measures of the above domains were selected, translated, and modified to suit the local culture, education, and socio-economic background of the target population. The measures were piloted and then administered to semi-urban Ugandan children aged 4;6-5;6, who included children who had started and not yet started school. RESULTS: Analysis of validity and reliability characteristics showed that 8 (at least one from each domain) out of the 11 measures were successfully adapted on the basis that they showed adequate task comprehension, optimum levels of difficulty to demonstrate individual and group differences in abilities, sensitivity to effects of age and education, and good internal as well as test-retest reliability. CONCLUSION: Translation and adaptation are realistic and worthwhile strategies for obtaining valid and reliable cognitive measures in a resource-limited setting.

We don't have language at our house: disentangling the relationship between phonological awareness, schooling, and literacy.

BACKGROUND: A strong link between phonological awareness (PA) and literacy exists, but the origins of this link are difficult to investigate, since PA skills are hard to test in young, pre-literate children, and many studies neither include such children nor report children's initial literacy levels. AIMS: To examine PA and literacy in children who are attending or not attending school in rural East Africa. SAMPLE: One hundred and eight children ages 7-10 years, with no education, or in grade 1 or 2, randomly selected from a community survey of all children in this age group. METHODS: PA skill, reading, cognitive abilities, and socio-economic status were examined. RESULTS: Implicit and explicit PA skill with small or large units is related to letter reading ability, and this effect is independent of age, schooling, and cognitive ability. Some PA tasks are performed above chance levels by children who cannot recognize single letters. CONCLUSIONS: Basic PA develops prior to the attainment of literacy, and learning to read improves PA both quantitatively and qualitatively.

Prevalence and risk factors of neurological disability and impairment in children living in rural Kenya.

BACKGROUND: There is little data on the burden of neurological impairment (NI) in developing countries, particularly in children of Africa. METHODS: We conducted a survey of NI in children aged 6-9 years in a rural district of Kenya. First, we screened for neurological disability by administering the Ten Questions Questionnaire (TQQ) to parents/guardians of children in a defined population. In phase two, we performed a comprehensive clinical and psychological assessment on children who tested positive on TQQ and on a similar number of children who tested negative. RESULTS: A total of 10 218 children were screened, of whom 955 (9.3%) were positive on TQQ. Of these, 810 (84.8%) were assessed, and of those who tested negative 766 (8.3%) were assessed. The prevalence for moderate/severe NI was 61/1000 [95% confidence interval (95% CI) 48-74]. The most common domains affected were epilepsy (41/1000), cognition (31/1000), and hearing (14/1000). Motor (5/1000) and vision (2/1000) impairments were less common. Of the neurologically impaired children (n = 251), 56 (22%) had more than one impairment. Neonatal insults were found to have a significant association with moderate/severe NI in both the univariate [odds ratio (OR) = 1.70; 95% CI 1.12-2.47] and multivariate analyses (OR = 1.30; 95% CI 1.09-1.65). CONCLUSIONS: There is a considerable burden of moderate/severe NI in this area of rural Kenya, with epilepsy, cognition, and hearing being the most common domains affected. Neonatal insults were identified as an important risk factor.

Interaction between phonological and grammatical processing in single word production in Kiswahili.

Grammatical priming of picture naming was investigated in Kiswahili, which has a complex grammatical noun class system (a system like grammatical gender), with up to 15 noun classes that have obligatory agreements on adjectives, verbs, pronouns and other parts of speech. Participants heard a grammatically agreeing (concordant), nonagreeing (discordant) or neutral prime before seeing a picture of a common object and being asked to name the object. Priming was found, with naming following concordant primes being faster than naming following the neutral prime ('say'). However, more interestingly, effects were found such that where two noun classes share a prefix, the grammatical prime from each of these two noun classes also primed words that have the same prefix but are not in the same noun class, and hence for which the prime was not grammatical. It is concluded that the prime appears to be facilitating the phonological form of the prefix rather than the syntacto-semantic group of words that are known as a noun class, and that the phonological form associated with a grammatical entity may be more significant in its processing than has previously been supposed.

Heavy schistosomiasis associated with poor short-term memory and slower reaction times in Tanzanian schoolchildren.

Cross-sectional studies of the relationship between helminth infection and cognitive function can be informative in ways that treatment studies cannot. However, interpretation of results of many previous studies has been complicated by the failure to control for many potentially confounding variables. We gave Tanzanian schoolchildren aged 9-14 a battery of 11 cognitive and three educational tests and assessed their level of helminth infection. We also took measurements of an extensive range of potentially confounding or mediating factors such as socioeconomic and educational factors, anthropometric and other biomedical measures. A total of 272 children were moderately or heavily infected with Schistosoma haematobium, hookworm or both helminth species and 117 were uninfected with either species. Multiple regression analyses, controlling for all confounding and mediating variables, revealed that children with a heavy S. haematobium infection had significantly lower scores than uninfected children on two tests of verbal short-term memory and two reaction time tasks. In one of these tests the effect was greatest for children with poor nutritional status. There was no association between infection and educational achievement, nor between moderate infection with either species of helminth and performance on the cognitive tests. We conclude that children with heavy worm burdens and poor nutritional status are most likely to suffer cognitive impairment, and the domains of verbal short-term memory and speed of information processing are those most likely to be affected.

Oral dyspraxia in inherited speech and language impairment and acquired dysphasia.

Half of the members of the KE family suffer from an inherited verbal dyspraxia. The affected members of the family have a lasting impairment in phonology and syntax. They were given various tests of oral praxis to investigate whether their deficit extends to nonverbal movements. Performance was compared to adult patients with acquired nonfluent dysphasia, those with comparable right-hemisphere lesions, and age-matched controls. Affected family members and patients with nonfluent dysphasia were impaired overall at performing oral movements, particularly combinations of movements. It is concluded that affected members of the KE family resemble patients with acquired dysphasia in having difficulties with oral praxis and that speech and language problems of affected family members arise from a lower level disorder.

Pitch and timing abilities in inherited speech and language impairment.

Members of the KE family who suffer from an inherited developmental speech-and-language disorder and normal, age-matched, controls were tested on musical abilities, including perception and production of pitch and rhythm. Affected family members were not deficient in either the perception or production of pitch, whether this involved either single notes or familiar melodies. However, they were deficient in both the perception and production of rhythm in both vocal and manual modalities. It is concluded that intonation abilities are not impaired in the affected family members, whereas their timing abilities are impaired. Neither their linguistic nor oral praxic deficits can be at the root of their impairment in timing; rather, the reverse may be true.

Pitch and timing abilities in adult left-hemisphere-dysphasic and right-hemisphere-damaged subjects.

The production and perception of pitch and rhythm were tested in patients with acquired unilateral left-hemisphere (LH) lesions (and subsequent motor dysphasia, n = 13), patients with unilateral right-hemisphere (RH) lesions (n = 14), and normal age-matched controls. While the LH dysphasic subjects were not generally impaired on the production or perception of pitch, they were grossly impaired on the production and perception of rhythm. The RH subjects, in contrast, were impaired on measures of pitch perception and production, including the discrimination and production of single notes and of melodies. It is concluded that the two hemispheres differ in their specialization for the perception and production of pitch and rhythm.

Neural basis of an inherited speech and language disorder.

Investigation of the three-generation KE family, half of whose members are affected by a pronounced verbal dyspraxia, has led to identification of their core deficit as one involving sequential articulation and orofacial praxis. A positron emission tomography activation study revealed functional abnormalities in both cortical and subcortical motor-related areas of the frontal lobe, while quantitative analyses of magnetic resonance imaging scans revealed structural abnormalities in several of these same areas, particularly the caudate nucleus, which was found to be abnormally small bilaterally. A recent linkage study [Fisher, S., Vargha-Khadem, F., Watkins, K. E., Monaco, A. P. & Pembry, M. E. (1998) Nat. Genet. 18, 168-170] localized the abnormal gene (SPCH1) to a 5. 6-centiMorgan interval in the chromosomal band 7q31. The genetic mutation or deletion in this region has resulted in the abnormal development of several brain areas that appear to be critical for both orofacial movements and sequential articulation, leading to marked disruption of speech and expressive language.