Biomedical subjects

Matthew J Burden

Publications and source records attributed to Matthew J Burden.

4 recordsLinked to original sources

PubMed2005

Effects of prenatal alcohol exposure on attention and working memory at 7.5 years of age.

BACKGROUND: A broad range of attentional and neuropsychological impairments have been demonstrated in children with fetal alcohol exposure. This study was designed to investigate which specific aspects of attentional function are most directly affected by moderate to heavy doses of prenatal alcohol exposure. METHODS: A total of 337 black children who were aged 7.5 years and recruited prospectively to overrepresent prenatal alcohol exposure at moderate to heavy levels were assessed on a diverse battery of neuropsychological tests. Principal components analyses were used to replicate and extend Mirsky et al.'s (1991) four-component model of attention. The relation of prenatal alcohol exposure to empirically derived attentional constructs was examined. RESULTS: Both the replicated and the extended attentional models produced solutions similar to the original Mirsky et al. model, reflecting elements of encode (working memory), shift, and focused and sustained attention, as well as a distinct component reflecting impulsivity. Adverse effects of maternal drinking across pregnancy were found primarily for working memory, and these effects were exacerbated when mothers were aged 30 or older at the time of the child's birth. CONCLUSIONS: These data confirm previous studies using diverse methods that suggest that working memory may be the most important aspect of attention that is adversely affected by prenatal alcohol exposure.

Adult↗

PubMed2005

Relation of prenatal alcohol exposure to cognitive processing speed and efficiency in childhood.

BACKGROUND: Prenatal alcohol exposure has been linked to deficits in processing speed in both infancy and later in childhood. This study was designed to examine prenatal alcohol-related deficits in both processing speed and processing efficiency in four domains of cognitive function. METHODS: Black children (n=337; age, 7.5 years), prospectively recruited to over-represent prenatal alcohol exposure at moderate-to-heavy levels, were assessed on four processing speed tasks, using a Sternberg paradigm. Hierarchical linear modeling was used to contrast overall processing speed, indicated by reaction time (RT) differences at the intercept, with processing efficiency, indicated by the slope of RT changes across increasing levels of task difficulty. Performance on these tasks within an effortful cognitive framework was compared with RT on a task involving relatively more automatic processing. Path analysis was used to examine the degree to which the effect of prenatal alcohol exposure on working memory was mediated by slower RT. RESULTS: Prenatal alcohol exposure was associated with slower processing speed on several of the Sternberg tasks, and the number comparison task showed a specific deficit in processing efficiency. These effects on tasks involving effortful processing contrasted with the lack of performance differences on the more automatic RT measure. The relation of prenatal alcohol exposure to working memory was mediated, in part, by an associated reduction in processing speed. CONCLUSIONS: These data confirm reports by other investigators linking prenatal alcohol exposure to slower processing speed and show that this RT deficit is found within the context of complex cognition but not where automatic processing is involved. The reduction in RT accounts, in part, for the previously reported alcohol-related effects on working memory. The number comparison slope was the only specific component of information processing affected, confirming previous reports of a distinctive prenatal alcohol effect on number processing.

Attention↗

PubMed2005

Implicit memory development in school-aged children with attention deficit hyperactivity disorder (ADHD): conceptual priming deficit?

Previous research has shown that children with attention deficit hyperactivity disorder (ADHD) often demonstrate performance deficits on effortful, strategic memory tasks, whereas relatively rote tasks of memory reveal no such deficit. Thus far, research in this domain has focused primarily on explicit memory. This study examined performance on multiple measures of implicit and explicit memory in children aged 7 to 14 years with and without ADHD. Memory for words and pictures was assessed at 15-min and 24-hr intervals. ADHD and non-ADHD groups performed similarly on tests of explicit memory (category-cued recall and recognition) and on perceptual aspects of implicit memory (word stem completion and picture fragment identification) as a function of age, retention interval, and stimulus format (i.e., picture or word). However, there was no evidence of priming on a conceptual implicit memory test (category exemplar generation) for boys with ADHD. This type of conceptual task, which is likely mediated by frontal systems, may indicate a unique memory deficit associated with ADHD.

Adolescent↗

PubMed2004

Rapid drop in infant blood lead levels during the transition to unleaded gasoline use in Santiago, Chile.

This study was conducted to relate blood lead levels in infants to changes in lead emissions in Santiago, Chile, a heavily polluted setting where leaded gasoline began to be replaced with unleaded gasoline in 1993. Over an 18-mo period, 422 infants had blood lead levels, cotinine, and iron status determined at 12 mo. Blood lead levels fell at an average rate of 0.5 microg/dl every 2 mo, from 8.3 to 5.9 microg/dl, as the city experienced a net fall of 30% in the quantity of leaded gasoline sold. Time progression, car ownership, serum cotinine, and type of housing were significantly associated with a blood lead level > or = 10 microg/dl. In this study, the authors demonstrated that infant blood lead levels, even if relatively low, can drop very rapidly in conjunction with decreases in environmental lead exposure.

Carcinogens↗