Predicting HIV disease progression in children using measures of neuropsychological and neurological functioning. Pediatric AIDS clinical trials 152 study team.

BACKGROUND: Neuropsychological testing and 2 measures of neurological status, cortical atrophy, and motor dysfunction were assessed for their usefulness in predicting human immunodeficiency virus (HIV) disease progression in infants, children, and adolescents who participated in Pediatric AIDS Clinical Trials Group Protocol 152 (PACTG 152). METHODS: A cohort of 722 antiretroviral therapy-naive children with symptomatic HIV infection were assessed at study entry and at later intervals. Assessments included neurodevelopmental testing, neuroradiologic imaging, and neurological examination of motor function. CD4 cell count and plasma RNA viral load also were measured. RESULTS: Children with the lowest neuropsychological functioning (IQ < 70) at baseline had the highest risk for later HIV disease progression (56%), compared with those with borderline/low (IQ = 70-89) functioning (26%), or with average or above (IQ > 90) functioning (18%). This was also true of week 48 neuropsychological functioning. Motor dysfunction (especially reduced muscle mass) at entry also predicted disease progression. Furthermore, motor dysfunction and week 48 neuropsychological functioning provided predictive information beyond that obtainable from surrogate markers of HIV disease status (eg, CD4 count, HIV RNA level). Children with cortical atrophy also were at higher risk for later disease progression, but when CD4 count and RNA viral load were known, cortical atrophy information provided no additional predictive information. CONCLUSIONS: Measures of neuropsychological and motor function status provide unique information regarding pediatric HIV disease progression. As such, these findings have important implications for predicting long-term outcomes (eg, longevity) in pediatric patients.

Cognitive impairment in adults with Down's syndrome: similarities to early cognitive changes in Alzheimer's disease.

Postmortem studies of brains from adults with Down's syndrome (DS) reveal a dramatic age-dependent increase in the incidence of neuropathology associated with Alzheimer's disease (AD). By the age of 40 years, virtually all DS individuals have AD neuropathology. Documentation of cognitive correlates of this phenomenon has been difficult, partly because of the preexisting mental retardation in DS. In the current study, we compared a group of adults with DS, 22 to 51 years old, with a matched control group on various behavioral measures such as savings scores, which are known to be sensitive in detecting early dementia in AD patients. By using the short delayed savings score from the California Verbal Learning Test (a test of verbal memory), a subgroup of DS adults was identified as memory-impaired. This group demonstrated a decline in performance on various other cognitive tests with advancing age, whereas another group identified as having non-memory-impaired DS, and the non-DS controls, showed no evidence of decline with age. These results provide evidence for the presence of early dementia among adults with DS within an age range in which neuropathologic manifestations of AD are predicted to be developing.

Pediatric AIDS: comparative cranial MRI and CT scans.

Fourteen consecutive children (age range: 4 months to 11 years; median: 4 years) with acquired immunodeficiency syndrome (AIDS) were studied prospectively with cranial magnetic resonance imaging (MRI) and unenhanced computed tomography (CT). In 4 children, human immunodeficiency virus infection was transfusion-related, while in 10, transplacental transmission occurred. Twelve children had abnormal neurologic examinations; of these, 10 had developmental delay and 2 were normal by developmental history and neurologic examination. Standardized neuropsychologic tests were given to all children; 5 were in the normal range and 9 demonstrated significant delays in verbal or motor/perceptual development. All children with abnormal neuropsychologic results were developmentally delayed; however, in 2 infants with normal neuropsychologic assessments, developmental delay and abnormal neurologic examinations were documented. Brain parenchymal volume loss (8 patients) and cervical lymphatic hypertrophy (4 patients) were demonstrated equally well by MRI and CT. CT alone demonstrated striatal-thalamic calcification (1 patient), whereas MRI alone demonstrated delayed myelination (1 patient). The extent of focal white matter lesions in 1 patient was demonstrated better by MRI than by CT. No intracranial mass lesions were demonstrated; however, significant correlations were found between peripheral volume loss imaged by either MRI or CT and both verbal and performance scores. In our small series, MRI offered no apparent advantage over CT in evaluating children with AIDS. We suggest that CT alone is sufficiently sensitive in evaluating pediatric AIDS-related brain abnormalities.

Cortical atrophy and cognitive performance in infantile nephropathic cystinosis.

A group of children and adolescents with infantile nephropathic cystinosis underwent cognitive testing and were examined for cortical atrophy using magnetic resonance imaging or computed tomography. Ten of 11 patients demonstrated cortical atrophy. A consistent pattern of lower cognitive performance was found in patients with greater atrophy; however, only the relationship between atrophy and short-term memory approached statistical significance. In addition, evidence for greater impairment of visual memory than of other cognitive functions was observed. This latter observation did not appear to be related to the degree of atrophy.

Sucrose and delinquency: behavioral assessment.

In this study, a double-blind challenge design was used to evaluate the hypothesis that sucrose ingestion may compromise the behavioral performance of juvenile delinquents. Subjects were 58 white delinquents, 57 black delinquents, and 39 white nondelinquents. The behavioral assessment included tasks that are relevant to delinquency and that might be expected to be disrupted following sucrose ingestion. The results provide no evidence that sucrose ingestion impairs the performance of juvenile delinquents. In fact, the results of several analyses indicated that the sucrose breakfast was associated with improved performance. In additional analyses the effect of sucrose on particular subgroups of juvenile delinquents was evaluated. Statistical interactions indicated that the performance of delinquents rated as more behaviorally disturbed benefited from sucrose ingestion, whereas those delinquents with less pronounced behavior problems tended to show impaired performance following a sucrose-loaded breakfast. These results indicate that simple statements regarding the effects of sucrose ingestion on behavior are likely to be misleading and highlight the need to consider individual difference variables when investigating the effects of sucrose on juvenile delinquents.

Effects of punishment on response latency in extraverts.

Previous findings indicate that in comparison to introverts, extraverts are prone to form responses that are resistant to interruption by punishment. Because the tendency to stop and reflect following punishment may be crucial for subsequent learning, the present study was designed to examine differences between introverts' and extraverts' reactions to punishment using response latency on the trial following punishment as the dependent variable. Sixty-six extraverted and 66 introverted male undergraduates performed a pattern-matching task in which they received noncontingent 50% success and 50% failure feedback under three incentive conditions including reward only, punishment only, or both. As predicted, a significant interaction was found in the both condition, reflecting the tendency of extraverts to respond more quickly and introverts more slowly following punishment feedback than following reward feedback. No significant effects were found in the other two conditions; however, a tendency was noted for extraverts to respond more quickly overall when only reward was given. A second experiment using reward-only and punishment-only feedback replicated this finding and yielded a significant interaction of Group X Condition. The results indicate that in contrast to introverts, extraverts are activated by the availability of reward and, paradoxically, that punishment may facilitate rather than interrupt extraverts' reward seeking behavior.

Ploidy effects in isogenic populations of alfalfa : I. Ribulose-1,5-bisphosphate carboxylase, soluble protein, chlorophyll, and DNA in leaves.

The influence of polyploidization on ribulose-1,5-bisphosphate carboxylase (RuBPCase), buffer-soluble protein (BSP), chlorophyll (Chl), and DNA was examined in fully expanded leaves of isogenic diploid-tetraploid (DDC 2X-4X) and tetraploid-octoploid (IC 4X-8X) sets of alfalfa (Medicago sativa L.). The concentration of RuBPCase in leaf extracts was determined by rocket immunoelectrophoresis. Activities of RuBPCase, expressed per milligram protein or per milligram Chl, and leaf tissue concentrations of RuBPCase, BSP, Chl, and DNA were similar between ploidy levels of the DDC 2X-4X set. Tetraploids and octoploids were similar in RuBPCase activities, expressed per milligram protein or per milligram Chl, and in leaf tissue concentrations of RuBPCase and DNA. Octoploids were significantly lower than tetraploids in concentrations of Chl and BSP.When compared on a per leaf basis, tetraploids were 80% higher in BSP and essentially double comparable diploids in fresh weight, RuBPCase, Chl, and DNA. The observation that leaves of the DDC tetraploid population contain twice as much DNA as comparable diploids suggests that leaves of both ploidy levels contain similar numbers of cells. Leaves of the octoploid population were 33% to 80% higher than corresponding tetraploids in BSP, fresh weight, RuBPCase, Chl, and DNA. Ratios of RuBPCase to DNA and Chl to DNA were similar across ploidy levels of both isogenic sets suggesting that cellular content of Chl and RuBPCase increases proportionately with the amount of DNA per cell.