A risk evaluation of the neuropsychological effects of childhood lead toxicity

Neuropsychological assessment of African children: evidence for a universal brain/behavior omnibus within a coconstructivist paradigm

Cross-cultural neuropsychology with African and American children provides evidence of consistent deficit patterns in attention, working memory, and learning in children at risk from disease affecting brain function by means of similar pathophysiologic mechanisms (e.g., cerebral malaria (CM) and sickle-cell disease (SCD); HIV in African and American children). These brain-behavior disease processes are also modified in a consistent manner cross-culturally by quality of developmental milieu and caregiving. We then present findings from the pioneering use of computerized cognitive rehabilitation therapy (CCRT) with Ugandan children surviving CM and with HIV. This neuropsychological evidence that CCRT enhances positive brain plasticity in a consistent manner across cultures supports the "coconstructive" paradigm (Li, 2003), since plasticity across the life span is the hallmark of this approach. Coconstructivism is a holistic multi-dimensional approach that emphasizes reciprocal biocultural influences across the life span. It also emphasizes the reciprocal interaction of culture and the genome in shaping brain/mind at multiple levels: neurobiological, cognitively, behavioral, and sociocultural (Li, 2003). Cross-cultural neuropsychology in healthy and diseased brains, brain imaging technologies, and genomic research can triangulate the manner in which a universal brain/behavior omnibus drives plasticity across the life span. As such, the further scientific characterization of the brain/behavior omnibus can provide the vital lynchpin between biology and culture in Li's coconstructive paradigm, revolutionizing our understanding of intelligence and culture.

Cisplatin-based therapy: a neurological and neuropsychological review

The present paper reviews research in the area of the broad-spectrum chemotherapeutic agent cisplatin (cis-diamminedichloro-platinum II) and examines the implications for clinical neuropsychology arising from the neurological disruption associated with cisplatin-based therapy. The paper begins with a brief review of cisplatin treatment in terms other than survival alone, and examines the side-effects and the potential central nervous system (CNS) dysfunction in terms of neurological symptoms and concomitant implications for neuropsychology. Two main implications for clinical neuropsychology arising from cisplatin therapy are identified. First, cisplatin therapy impacts upon the psychological well-being of the patient, particularly during and in the months following treatment. It is suggested that during this time, a primary role for neuropsychology is to focus upon the monitoring and the active enhancement of the patient's social, psychological and spiritual resources. Second, with regard to neurocognitive changes, the review suggests that (1) neurocognitive assessment may not yield stable results within 8 months following treatment and (2) while perceptual, memory, attentional and executive dysfunction may be predicted following cisplatin treatment, little systematic research has been carried out to investigate such a possibility. Future research might profitably address this issue and also specifically examine the effects of low dosage cisplatin-based therapy and the effects of recently developed neuroprotective agents. Finally, there is some evidence to suggest that women may be more susceptible to neurotoxicity during cisplatin therapy, but no gender-related cognitive effects are reported in the cisplatin literature. Future research could usefully investigate gender differences in association with cisplatin chemotherapy.

Central lead administration inhibits water intake and sodium appetite in rats

We have demonstrated that acute third ventricle injections of lead acetate (PbAc) exert a powerful antidipsogenic effect and induce a significant increase in renal sodium excretion. In the present study we confirm the antidipsogenic effect of lead and demonstrate that central administration of this metal, in minute amounts, significantly reduces salt intake both during dehydration and after central angiotensinergic stimulation. Adult male Wistar rats had the third ventricle cannulated seven days before the experiments. During this period they had free access to distilled water and hypertonic saline solution (1.5%). After a 24-h period of fluid deprivation, experimental animals received third ventricle injections of PbAc (0.3, N = 8 and 3.0 nmol/rat, N = 14) while controls received sodium acetate (NaAc; 3.0 nmol/rat, N = 10). Rats treated with PbAc at the highest dose showed a significant reduction (P<0.05) both in water and hypertonic saline intake when compared to controls. When the effect of lead administration on angiotensin II-induced water and salt intake was studied, normohydrated animals received third ventricle injections of angiotensin II (9.6 nmol/rat) after pretreatment with 3.0 nmol/rat of PbAc (experimental group, N = 10) or NaAc (controls, N = 8). The group pretreated with PbAc presented a significant reduction (P<0.05) in both water and salt intake compared to controls. Thus, this study confirms the antidipsogenic effect of central lead injections and demonstrates that the presence of lead in the brain exerts a significant inhibition of sodium appetite.

Minimal behavioral effects from moderate postnatal lead treatment in rats

Developmental lead exposure continues to be a worldwide problem. This study investigated the behavioral effects resulting from developmental lead treatment in rats with corresponding physiological measures of lead exposure. Sprague-Dawley rats were treated with 350 ppm lead acetate from birth to weaning via the dam's drinking water. Behavioral measures assessed in the offspring included residential activity tests, complex maze performance, acoustic startle response, emergence behavior (light/dark preference), prepulse inhibition, and ethological assessments of play, dominance, and burrowing. Pb blood levels averaged 53 microg/dl in the dam at the time of offspring weaning and 46 microg/dl in weanling female offspring. Pb levels averaged 277 ng/g and 32 microg/g in the brain and bone, respectively, of female offspring at weaning. No behavioral assessment indicated any lead-related functional alterations nor were there any statistically significant differences when the lead-treated group was restricted to rats in those litters that were above the median Pb blood lead level at weaning. These results indicate that any lead-related functional alterations at this dose may be subtle and require a sufficient demand on the system for detection.