Stroke in the Lehigh Valley: risk factors for recurrent stroke.

Age-specific risk of recurrent stroke for various risk factors, calculated independently, was estimated using the first year of data from the Lehigh Valley Stroke Register. The register is based on a population of more than one-half million. Among the risk factors examined, the highest overall risk of recurrent stroke, 41.4, occurred with a history of at least one transient ischemic attack (TIA). After myocardial infarction (MI), the relative risk of a recurrent stroke was 8.0, while with all other heart diseases combined it was 8.4. With diabetes, the relative risk of a recurrent stroke was 5.6; with hypertension, it was 4.5. The relative risk increased with age after TIA and MI, but not for other heart disease, diabetes, and hypertension, except in the 85+-year-old age group.

Effects of MK-801 on spatial memory in homing and nonhoming pigeon breeds.

Homing pigeon breeds, the product of artificial selection on the basis of navigational and spatial ability, differ from nonhoming breeds in hippocampal size and distribution of N-methyl-D-aspartate (NMDA) dependent receptors. The effects of MK-801 (0.1 mg/kg administered intraperitoneally), a noncompetitive NMDA antagonist, on spatial reference memory (RM) were compared between the 2 breeds in a radial arm maze task. MK-801 disrupted the acquisition of RM in the nonhoming group but not the homing group, which was equivalent to the 2 saline-only control groups. As in previous findings with mammals, working memory was not affected by MK-801. This behavioral dissociation, coupled with differences in NMDA-dependent long-term potentiation between breeds, suggests an exceptional opportunity to investigate the role and function of the dorsomedial telencephalon region in spatial RM, through anatomical, neurochemical, and behavioral comparisons between homing and nonhoming pigeon breeds.

The Lehigh Valley Stroke Program: establishing a communitywide, hospital-based stroke register.

A communitywide, hospital-based stroke register has been established in the Lehigh Valley of Pennsylvania and New Jersey. The Lehigh Valley has about 600,000 inhabitants and is geographically somewhat isolated. Ninety-five percent of the people are white, and the population has an age-sex distribution like that of the United States as a whole. All patients falling into any of nine diagnostic categories of stroke or transient ischemic attack are registered on admission to a hospital, and medical, social, and demographic data are abstracted onto precoded data forms. A single neurologist assigns definitive diagnoses according to standardized criteria after reviewing all of the medical data. The stroke register provides a new and powerful tool for collecting population-based data on a large number of cases in a short-time. After adjusting for demographic differences, epidemiologic studies can be carried out that may be generalizable to the entire United States. Several organizational aspects of the register and its operation are described in this report, and examples of the types of information and statistics readily calculable from the data in the register are given. The completeness of the stroke ascertainment and the large population registered also offer an excellent opportunity for any interested researcher to investigate the relationships between medical, social, and demographic conditions on the one hand and stroke risk on the other; to study the efficacy of prevention and treatment programs; and to determine health care provision requirements in a well-defined population.

Auditory priming in an implicit memory task that emphasizes surface processing.

Auditory priming was examined in an implicit memory task, phoneme monitoring, that emphasized surface processing. The contribution of voice to priming was investigated in single- and multiplespeaker environments by repeating studied words at test in either the same voice or different voices. Multiple-speaker environments, which preserved both acoustic and word repetition, eliminated priming when more than two voice changes between words were introduced. When voice familiarity attenuated acoustic variability, priming was reestablished in the condition in which three voices were heard. Voice changes between study and test, which eliminated acoustic repetition, also abolished priming. Word frequency affected reaction times but not priming. This demonstrated that priming entailed subword processing rather than word processing. This study demonstrates that the significance of voice in implicit memory is dependent on the level of processing required by the task and the acoustic environment. Supported in part by an OMRDD Fellowship in the CSI/IBR Center for Developmental Disabilities to M. P., portions of this study were conducted in partial fulfillment of her requirements for the Ph.D. in the Department of Psychology of The City University of New York Graduate School and University Center.

Stroke in the Lehigh Valley: incidence based on a community-wide hospital register.

Since July 1982 a population-based study of stroke has been carried out in the Lehigh Valley, a region in Pennsylvania and New Jersey, USA, with 580,000 people. During the first year, the annual incidence rates of stroke and transient ischemic attack were 167 and 49 per 100,000 population, respectively. Cerebral thrombosis, embolus, cerebral hemorrhage and subarachnoid hemorrhage accounted for 76, 13, 8 and 3% of the strokes, respectively. The overall incidence rate and distribution of stroke by type agree well with other population-based studies. The large size of the population in the Lehigh Valley means that information on the epidemiology of stroke, as well as the effects of various therapies on stroke frequency and outcome, can be collected in a shorter period of time than in most other communities studied to date. Finally, an assessment of concordance in diagnosis between attending physicians and a neurologist using standardized criteria was possible for the entire community.