Lawrence A. Coben

A longitudinal EEG study of mild senile dementia of Alzheimer type: changes at 1 year and at 2.5 years.

This longitudinal study of resting EEGs compared patients with senile dementia of Alzheimer type (SDAT) and healthy controls at 3 times of testing over a 2.5 year period. Measures included the mean EEG frequency as well as the percentage of power in alpha, beta, theta, and delta frequency bands obtained from power spectral analysis. The values from occipital to vertex derivations were averaged for the left and right hemispheres. In healthy older adults delta increased, and both beta and mean frequency decreased over the study period; there was no significant change in theta or alpha. In the SDAT group, all 5 EEG measures changed significantly; there were increases in delta and theta, and decreases in beta, alpha and mean frequency. Theta percentage power distinguished between all 4 stages of dementia (control, mild, moderate and severe). Other EEG measures discriminated only at certain stages. In the mild stage of SDAT theta, beta and mean frequency were already different from control values. In the moderate stage, these differences persisted, and alpha became different. Delta was the last to change, and in the present small sample of those with severe SDAT the difference had not yet reached significance.

Predictive features in mild senile dementia of the Alzheimer type

Forty-three subjects with mild senile dementia of the Alzheimer type, diagnosed and staged by clinical research criteria, were studied with clinical, psychometric, EEG, visual evoked potential, and CT measures. During the 12 months following entry into the study, 21 subjects progressed to moderate or severe dementia, 21 remained mild, and one was lost to follow-up. Many of the clinical and psychometric measures of impairment were predictive of the progression to moderate or severe dementia. Electrophysiologic and CT measures were not. In a discriminant function analysis, the scores on two measures (the digit symbol subtest of the Wechsler Adult Intelligence Scale and an Aphasia Battery) correctly predicted the stage of dementia 1 year later in 95% of the subjects.

Replication of a study of frequency analysis of the resting awake EEG in mild probabke Alzheimer's disease ☆

In the resting EEG, the percentage power in the delta, theta, alpha, and beta bands and the mean frequency were computed in an occipital-vertex derivation for two samples of subjects. The original sample (n = 79) and the new sample (n = 43) each contained a mild probable Alzheimers disease (SDAT) group and a healthy elderly control group. Group medians in both samples were higher in the SDAT than in the healthy subjects for percentage delta and theta, and were lower for percentage alpha and beta and for mean frequency. Percentage theta and mean frequency were consistent across the two samples in showing statistically significant differences between SDAT and healthy groups. The ability of each EEG measure to detect individual subjects with SDAT was assessed. The most effective measure, percentage theta, had only modest sensitivity (about 20%), but this was attained at a specificity of 100%. The accurate detection of an individual at the mild stage requires that the predictive value of a positive test be high to avoid misclassification of non-SDAT subjects as SDAT. This, in turn, requires a specificity of virtually 100% when the prevalence is low. The low sensitivity puts several constraints on the usefulness of the EEG. For this reason, when the dementia is at the mild stage the EEG would be a useful detector of probable Alzheimers disease only under certain limiting conditions, including high prevalence, high specificity, and a willingness to accept a high rate of falsely negative tests.

Visual evoked potentials in mild senile dementia of alzheimer type

Visual evoked potentials (VEPs) to chessboard shift and to flash stimulation were recorded from 40 subjects with senile dementia of Alzheimer type (SDAT) and 40 individually matched control subjects. All of the SDAT subjects had only a mild degree of dementia and were still living in the community. Analysis of variance showed significant differences between demented and control group means for 3 chessboard shift VEP measures, the demented group having longer latency of peaks P3 and N3, and larger amplitude of segment N2-P3. These three are the earliest reported changes in the VEP in Alzheimer disease, since the flash VEPs showed no measure in which the demented and control group means differed significantly.

Iodide transfer at four cerebrospinal fluid sites in the dog: Evidence for spinal iodide carrier transport

Abstract In the adult dog under pentobarbital, cerebrospinal fluid (CSF) was sampled from the lateral ventricle and from the cisternal, lumbar, and parasagittal subarachnoid spaces. The choroid plexuses of the lateral ventricle were also excised. Values of the net iodide uptake in these samples were compared at 2 hr after an intraperitoneal injection consisting of 2.0 mc Na 131 I combined with doses of Na 127 I varying from 1.0 to 800 mg/kg. Similar samples were analyzed from dogs whose lumbar subarachnoid space had been isolated from intracranial carriers by thoracic transection or epidural ligation. In another series of dogs, the effect of saturating levels of Na 127 I in the spinal subarachnoid space isolated from intracranial carriers was tested by continuous thoracolumbar perfusion with artificial CSF containing Na 131 I and Na 127 I. The existence of a spinal iodide carrier system was suggested by the small net uptake of iodide in normal lumbar CSF, and by the progressive rise in this uptake as saturating doses of Na 127 I were added to the blood. The similar behavior of lumbar CSF iodide uptake after isolation of the spinal subarachnoid space implicated an extracranial mechanism. That this mechanism was a carrier transport system was strongly supported by the finding, during perfusion of the isolated thoracolumbar subarachnoid space, of decreased clearance of iodide from perfused artificial CSF when saturating levels of Na 127 I were added to the perfusion fluid. The site of action of the spinal iodide carrier system is unknown, but certain restrictions upon the anatomical possibilities are noted.

10 Progression of Senile Dementia of the Alzheimer Type on a Battery of Psychometric Tests

Publisher Summary This chapter describes progression of senile dementia of the alzheimer type on a battery of psychometric tests. Alzheimers disease is a progressive, deteriorative disease. As described in the chapter, it typically first attacks the individuals ability to learn and remember new information, but as the disease progresses, a wide range of higher cortical functions are affected. The search for correlates of rate of deterioration in SDAT takes two general forms. The first focuses on risk factors. One commonly examined is age at onset of the disease. Other risk factors include concomitant features of the disease in its early stages that may be associated with more rapid decline. The chapter includes a description of attempts to identify correlates of progression (deterioration) on the battery of psychometric tests included in the longitudinal study. It differs in several important ways from the earlier reports from this same sample that focused on progression.

Slow wave artifacts seen with chopper type EEG during high frequency stimulation

Abstract Slow wave artifacts (e.g. 3/sec.) may be mistaken for evoked cortical responses to subcortical high frequency (e.g. 100–300/sec.) stimulation, if chopper type EEG-amplifiers are used. The artifacts are present only during the high frequency stimulation. Evidence is presented which indicates that the artifacts result from a heterodyne or “beat” effect between the vibrator system of the amplifier and the incoming stimulus.

The Events that Led to the Treaty of Tordesillas

The events leading to the Treaty of Tordesillas began when Columbus returned from his first voyage. Spain and Portugal competed in the attempt to obtain their desired rights of navigation and conquest in the Atlantic Ocean and to be the first Europeans to the Indies. The combined versions of what happened by Davenport (1917) and Nowell (1945) exemplify the historical narrative of these events. The present paper’s version of the narrative considers for inclusion ten items absent from these two previous accounts. Three of these ten new items are considered here to be highly probable: King João’s pony express, his 1488 threat of war with Spain over the marriage of his son, and Freire’s discovery not only of missing chancery records, presumably of King João’s southern Atlantic voyages, but also of contemporaneous records containing the ship’s biscuit data suggesting long Atlantic voyages. The other seven new items must await additional documentation if they are to be considered highly probable. Using some highly probable items as well as some deemed less than highly probable, the present article offers an explanation for the behavior of both King João and King Ferdinand in the latter’s ultimate agreement that the treaty should move the line of demarcation westward.

How small was a shtetl

The purpose of this study was to apply the recently proposed definition of a shtetl (Samuel D. Kassow, “The Shtetl,” in The YIVO Encyclopedia of Jews in Eastern Europe, ed. Gershon D. Hundert, New Haven, CT: Yale University Press, 2007), to the problem of determining the lower limit of shtetl size, if any, by relating the size of the Jewish population in a given site to the degree to which the site fits the definition. The definition of the shtetl used here is based on the presence of the five institutions needed for observance by an orthodox Jewish community, namely a free-standing synagogue, a heder, a mikveh, two or more charitable hevres, and a local Jewish cemetery. For each of 56 putative shtetl sites in Eastern Europe c.1845–1940, information on the presence or absence of these institutions was found in a memoir. The number of Jewish residents in these sites ranged from about 2600 to about 40. Each site was classified as either a shtetl, a potential shtetl, or a non-shtetl. The smallest shtetl had a Jewish population of about 200. This provides an estimate of the lower limit of shtetl size, in terms of Jewish population. The data suggest that the non-shtetl – more aptly called the “pre-shtetl” – is an entity separate from the shtetl as here defined.

A note on shtetl definitions and the dating of the first shtetl

Consideration of two different working definitions of a shtetl, and the two different datings of the first shtetl that they produce, leads to the following conclusions. (1) The definition of a shtetl is formed by a set of criteria, one of which distinguishes it from similar settlements by providing a characteristic termed “sufficient Jewishness.” Because “sufficient Jewishness” exists in multiple forms, such as “at least 40% Jewish population,” and “the presence of certain specified institutions of religious observance,” a number of valid definitions can coexist. (2) The dating of the earliest shtetl will vary from one study to another, because it is determined by the selected definition of a shtetl used to arrive at that dating, and ultimately by the selected form of that definitions distinguishing criterion. (3) Therefore, just as more than one definition of a shtetl can coexist, each with a different form of the distinguishing criterion, so more than one valid dating of the first shtetl can coexist.