Biomedical subjects

Karen Bolla

Publications and source records attributed to Karen Bolla.

6 recordsLinked to original sources

PubMed2006

Neurological assessments of marijuana users.

This chapter summarizes the neurological approaches used to assess the potential long-term effects of drugs on the nervous system of drug abusers. These include the use of neuropsychological assessments, transcranial Doppler (TCD) sonography, and electroencephalographic (EEG) recordings. Neuropsychological procedures are used in an effort to provide an unbiased estimate of the individual's cognitive capacity, and included tests of language skills, attention, memory, and motor skills. TCD allows for the measurements of blood flow in the anterior cerebral and middle cerebral arteries, which supply blood to the cortex. An EEG recording was included in our assessment on marijuana abusers using a sound-attenuated, electronically shielded chamber. These neurological approaches have allowed the detection of various neurological and neurovascular deficits that are associated with the abuse of marijuana.

Electroencephalography↗

PubMed2005

Blood mercury levels and neurobehavioral function.

CONTEXT: Due to its cardiovascular benefits, fish consumption is widely encouraged among older Americans. However, this fast-growing population is at increased risk of cognitive impairment and may be particularly sensitive to methylmercury, a neurotoxicant found in fish. OBJECTIVE: To describe associations of blood mercury levels with neurobehavioral test scores in an urban adult population. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional analysis to determine the effect of mercury levels on neurobehavior in 474 randomly selected participants in the Baltimore Memory Study, a longitudinal study of cognitive decline involving 1140 Baltimore residents aged 50 to 70 years. We measured total mercury in whole blood samples and used multiple linear regression to examine its associations with neurobehavioral test scores. First-visit data were obtained in 2001-2002. MAIN OUTCOME MEASURES: Twenty scores from 12 neurobehavioral tests. RESULTS: The median blood mercury level was 2.1 microg/L (range, 0-16 microg/L). After adjustment for covariates, increasing blood mercury was associated with worse performance on Rey complex figure delayed recall, a test of visual memory (beta, -0.224; 95% confidence interval, -0.402 to -0.047). However, increasing blood mercury levels were associated with better performance on finger tapping, a test of manual dexterity (beta for dominant hand, 0.351; 95% confidence interval, 0.017-0.686). CONCLUSION: Overall, the data do not provide strong evidence that blood mercury levels are associated with worse neurobehavioral performance in this population of older urban adults.

Adult↗

PubMed2005

Occupational lead exposure and longitudinal decline in neurobehavioral test scores.

BACKGROUND: No previous longitudinal studies have compared and contrasted associations of blood lead and tibia lead with declines in cognitive function over the course of time in a large sample of subjects with current and past occupational exposure to inorganic lead. METHODS: From 1997 through 2001, we conducted a longitudinal study of 803 current and former lead workers in South Korea to evaluate effects on the central and peripheral nervous systems. Three study visits occurred during a mean follow-up duration of 2.20 years. Neurobehavioral test scores, peripheral nervous system function, and blood lead were measured at each of the 3 study visits, whereas tibia lead was measured by x-ray fluorescence at the first and second visits. We limited our analysis to the 576 lead workers who completed testing at all 3 visits. We performed regression analyses using generalized estimating equations. RESULTS: There were consistent associations of blood lead with test scores at baseline and of tibia lead with declines in test scores over the next year, mainly in executive abilities, manual dexterity, and peripheral vibration threshold. CONCLUSIONS: The results support the inference that occupational lead exposure can cause declines in cognitive function over the course of time. Lead likely has an acute effect on neurobehavioral test scores as a function of recent dose and a longer-term (possibly progressive) effect on cognitive decline as a function of cumulative dose.

Adult↗

PubMed2004

Prefrontal cortical dysfunction in abstinent cocaine abusers.

The anterior cingulate cortex (ACC) and lateral prefrontal (LPFC) cortex are brain regions important to executive cognitive functions (ECF). We determined ACC and LPFC function in 23-day abstinent cocaine abusers using positron emission tomography (PET H(2)(15)O) during performance of a modified version of the Stroop Task. Cocaine abusers showed less activation than non-drug-using comparison subjects in the left ACC and the right LPFC and greater activation in the right ACC. Average amount of cocaine used per week was negatively correlated with activity in the rostral ACC and right LPFC. Disruption of ECF in substance abusers could interfere with attempts to stop drug use and undermine treatment. Since impairment in ECF may be a common feature of various neuropsychiatric disorders, these findings have applicability beyond the neurobiology of addiction.

Adult↗

PubMed2003

Neural substrates of decision making in adults with attention deficit hyperactivity disorder.

OBJECTIVE: The characteristics of attention deficit hyperactivity disorder (ADHD) include abnormalities in reward responsivity that may interfere with decision making. The study examined reward responsivity in ADHD by comparing the neural correlates of decision making in adults with childhood-onset ADHD and in healthy adults. METHOD: The neural correlates of performance on a decision-making task and a control task were compared in 10 adults with ADHD and 12 age-matched healthy volunteers by using [(15)O]H(2)O positron emission tomography. The decision-making task tested the ability to weigh short-term rewards against long-term losses. The control task matched all components of the decision-making task except for the decision-making process and related contingency. RESULTS: The ventral and dorsolateral prefrontal cortex and the insula were activated during performance of the decision-making task in both the ADHD and healthy groups; however, activation in the ADHD group was less extended and did not involve other regions, such as anterior cingulate and hippocampus, that subserve emotion/memory processes. Direct comparison of data from the ADHD subjects and the healthy volunteers suggested that the healthy subjects engaged the hippocampal and insular regions more than did the ADHD subjects and that the ADHD subjects recruited the caudal part of the right anterior cingulate more than did the healthy subjects. CONCLUSIONS: The findings suggest that the neural circuits engaged during decision making differ in subjects with ADHD and healthy comparison subjects. This difference may explain observed deficits in motivated behaviors in ADHD. A better understanding of the nature of these deficits could ultimately be applied to refine treatment strategies for ADHD.

Adult↗

PubMed2002

Decision-making in a risk-taking task: a PET study.

As decision-making is central to motivated behavior, understanding its neural substrates can help elucidate the deficits that characterize various maladaptive behaviors. Twenty healthy adults performed a risk-taking task during positron emission tomography with (15)O-labeled water. The task, a computerized card game, tests the ability to weigh short-term rewards against long-term losses. A control task matched all components of the risk-taking task except for decision-making and the difference between responses to contingent and non-contingent reward and punishment. Decision-making (2 runs of the active task minus 2 runs of the control task) activated orbital and dorsolateral prefrontal cortex, anterior cingulate, insula, inferior parietal cortex and thalamus predominantly on the right side, and cerebellum predominantly on the left side. In an exploratory analysis, guessing (run 1 minus run 2 of the active task) accompanied activation of sensory-motor associative areas, and amygdala on the left side, whereas informed decision-making (run 2 minus run 1) activated areas that subserve memory (hippocampus, posterior cingulate) and motor control (striatum, cerebellum). The findings provide a framework for future investigations of decision-making in maladaptive behaviors.

Adult↗