While the application of normative standards is vital to the practice of clinical neuropsychology, data regarding normative change remains scarce despite the frequency of serial assessments. Based on 285 normal individuals, we provide co-normed baseline data with demographic adjustments and test-retest standardized regression based (SRB) models for three time points for several measures. These models delineate normal, expected change across time, and yield standardized z-scores that are comparable across tests. Using a new approach, performance on any previous trial was accounted for in the subsequent models of change, yielding serial normative formulas that model change trajectories rather than simple change from point to point. These equations provide indices of deviation from expected baseline and change for use in clinical or research settings.

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The prediction of change: Normative neuropsychological trajectories.

The human illness designated as possible estuarine-associated syndrome (PEAS) by the Centers for Disease Control and Prevention (CDC) has been associated with exposure to estuaries inhabited by tox...

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Possible estuary-associated syndrome: symptoms, vision, and treatment.

Various Barona formulae, a WTAR algorithm based on demographic data, and WRAT-3 oral reading methods of estimating premorbid ability were compared in a diverse research sample of 119 subjects. These methods were correlated with one another and with a modified version of the Raven Standard Progressive Matrices. Descriptive data are provided to illustrate advantages and disadvantages of various methods of estimating premorbid ability when no formal intellectual testing is available. While predicting premorbid ability for individual subjects involves varying degrees of error, we found that the revised Barona formula was superior to the original formula for subjects at the upper end of ability level. When researchers have screened out learning disability and have subject samples with few individuals likely to be of superior premorbid intelligence, oral reading scores are a reasonable measure of premorbid ability. Otherwise, researchers are advised to use both demographic and oral reading methods to estimate p...

Comparative Utility of Barona Formulae, Wtar Demographic Algorithms, and WRAT-3 Reading for Estimating Premorbid Ability in a Diverse Research Sample

The U.S. Environmental Protection Agency assisted the North Carolina Department of Health and Human Services in conducting a study to investigate the potential for an association between fish kills in the North Carolina estuary system and the risk for persistent health effects. Impetus for the study was recent evidence suggesting that estuarine dinoflagellates, including members of the toxic Pfiesteria complex (TPC), P. piscicida and P. schumwayae, may release a toxin(s) that kills fish and adversely affects human health. This report describes one component of the study in which visual system function was assessed. Participants working primarily in estuaries inhabited by TPC or in offshore waters thought not to contain TPC were studied. The potentially exposed estuary (n = 22) and unexposed offshore (n = 20) workers were matched for age, gender, and education. Visual acuity did not differ significantly between the cohorts, but visual contrast sensitivity (VCS), an indicator of visual pattern-detection abi...

Human visual function in the North Carolina clinical study on possible estuary-associated syndrome.

In connection with the CDC National Conference on Pfiesteria, a multidisciplinary panel evaluated Pfiesteria-related research. The panel set out what was known and what was not known about adverse effects of the organism on estuarine ecology, fish, and human health; assessed the methods used in Pfiesteria research; and offered suggestions to address data gaps. The panel's expertise covered dinoflagellate ecology; fish pathology and toxicology; laboratory measurement of toxins, epidemiology, and neurology. The panel evaluated peer-reviewed and non-peer-reviewed literature available through June 2000 in a systematic conceptual framework that moved from the source of exposure, through exposure research and dose, to human health effects. Substantial uncertainties remain throughout the conceptual framework the panel used to guide its evaluation. Firm evidence demonstrates that Pfiesteria is toxic to fish, but the specific toxin has not been isolated or characterized. Laboratory and field evidence indicate that the organism has a complex life cycle. The consequences of human exposure to Pfiesteria toxin and the magnitude of the human health problem remain obscure. The patchwork of approaches used in clinical evaluation and surrogate measures of exposure to the toxin are major limitations of this work. To protect public health, the panel suggests that priority be given research that will provide better insight into the effects of Pfiesteria on human health. Key gaps include the identity and mechanism of action of the toxin(s), the incomplete description of effects of exposure in invertebrates, fish, and humans, and the nature and extent of exposures that place people at risk.

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Pfiesteria : review of the science and identification of research gaps. Report for the National Center for Environmental Health, Centers for Disease Control and Prevention

INTRODUCTION Estuary-Associated Syndrome (EAS) is the name given to a potential illness characterized primarily by changes in an individual's cognitive abilities, including acute onset of memory loss or the sudden inability to solve simple problems. Other possible signs of illness include respiratory symptoms, skin rash, or gastrointestinal distress. This illness appears to arise following exposure to toxin produced by Pjiesteria piscicida, or other toxic dinoflagellates, that resides in estuary waters. In 1988, researchers at the College of Veterinary Medicine, North Carolina State University, observed the unusual death offish in laboratory tanks following exposure to water from the Pamlico River Estuary in North Carolina (Smith et al., 1988). A toxic dinoflagellate was identified in association with the fish deaths and researchers at North Carolina State University were able to reproduce the fish toxicity in a laboratory setting (Burkholder et al., 1992). The organism was named Pjiesteria piscicida (Lewitus et al., 1995; and Steidinger et al., 1996). In 1995, this dinoflagellate was found in the Chesapeake Bay (Lewitus et al., 1995) and more recently in creeks and rivers of Maryland and Virginia (Marshall, personal communication 1999; Grattan et al., 1998). It is now generally recognized that there is a complex of Pjiesteria-like dinoflagellates, including P. piscicida and an estimated ten or 11 similar organisms. These have been referred to as Pjiesteria-complex organisms and more recently as Pjiesteria-like organisms (PLOs). PLOs have a complex life cycle and reside in different forms in the sediment or the water column of estuarine waters. They appear to require live finfish or their secreta for transformation to a toxic phase with subsequent release of a powerful exotoxin(s). Because of the many different forms for these organisms, speciation is difficult and the accepted method depends on scanning electron microscopy (SEM). Screening for PLOs in water samples is currently done using a light microscope with SEM performed if high concentrations of PLOs are seen. Different laboratories have developed molecular methods to identify these organisms in water samples and these methods are being tested (Oldach et al., 1998; Rublee et al., 1999). Work is also ongoing to develop a test to analyze released toxins.

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John Taylor

Papers

A Cohort Study to Determine the Epidemiology of Estuary-Associated Syndrome