Dysphagia management for progressive neurological conditions.

This article discusses some of the issues surrounding dysphagia management for patients with progressive neurological conditions. It is important that health professionals are aware of the available options and that they consider patients' wishes to meet their nutritional needs.

Electrophysiological correlates of categorization: P300 amplitude as index of target similarity.

Two experiments examined event-related potentials (ERPs) and behavioral correlates of categorizing stimuli varying in perceptual similarity to targets. Participants performed a target-detection task in which non-target stimuli varied in target similarity but occurred with equivalent probability. The stimuli were variations of a schematic human face comprised of eight distinct features: two eyes, two eyebrows, one nose, one mouth, and two ears. Non-target stimuli that were perceptually similar to targets produced larger P300-like neurophysiological responses than did other non-target stimuli. These effects emerged whether participants' target was relatively complex (eight features) or quite simple (zero features). Accordingly, the presence of many constituent elements of a test stimulus does not appear necessary to trigger increases in categorical processing of non-targets that are similar to a target. The data further suggest that the P300 amplitude may be used as a good index of perceptual similarity between target and non-target stimuli.

Interventions for treating schistosomiasis haematobium.

BACKGROUND: Schistosomiasis is a parasite that is carried by freshwater snails. There are two common forms, urinary schistosomiasis (which is considered in this review) and intestinal schistosomiasis. OBJECTIVES: The objective of this review was to assess the effects of drugs for treatment of Schistosomiasis haematobium. SEARCH STRATEGY: The Cochrane Infectious Diseases Group trials register, Medline and reference lists of articles were searched. The WHO Division of Control of Tropical Diseases was contacted. SELECTION CRITERIA: Randomised trials of metrifonate or praziquantel or other drugs for treating Schistosomiasis haematobium. DATA COLLECTION AND ANALYSIS: One reviewer assessed trial quality and extracted data, and this was checked by a review editor. MAIN RESULTS: Five trials, all from Africa, were included. The quality of the trials was variable. There were no good randomised controlled trials of praziquantel single dose treatment versus current standard treatment with metrifonate of three doses of 10 milligrams per kilogram at two weekly intervals. Praziquantel at doses of 40 milligram per kilogram was more effective than single dose metrifonate 10 milligrams per kilogram (odds ratio 6.94, 95% confidence interval 4.85 to 9.92). In one trial of metrifonate compared with praziquantel, there was no difference demonstrated in a range of clinical outcomes including cessation of haematuria and proteinuria. Both drugs improved nutritional status and physical fitness. REVIEWER'S CONCLUSIONS: Praziquantel (single dose) appears to be more effective than metrifonate (split dose) in terms of parasitological cure of Schistosomiasis haematobium, but the reinfection rate is high with both drugs.

School and neuropsychological performance of evacuated children in Kyiv 11 years after the Chornobyl disaster.

This paper examines the cognitive and neuropsychological functioning of children who were in utero to age 15 months at the time of the Chornobyl disaster and were evacuated to Kyiv from the 30-kilometer zone surrounding the plant. Specifically, we compared 300 evacuee children at ages 10-12 with 300 non-evacuee Kyiv classmates on objective and subjective measures of attention, memory, and school performance. The evacuee children were not significantly different from their classmates on the objective measures (grades; Symbolic Relations subtest of the Detroit Test; forms 1 and 2 of the Visual Search and Attention Test; Benton Form A; Trails A; Underline the Words Test) or on most of the subjective measures (the attention subscale of the Child Behavior Checklist completed by mothers; the attention items of the Iowa Conners Teacher's Rating Scale; mother and child perceptions of school performance). The one exception was that 31.3% of evacuee mothers compared to 7.4% of classmate mothers indicated that their child had a memory problem. However, this subjective measure of memory problems was not significantly related to neuropsychological or school performance. No significant differences were found in comparisons of evacuees and classmates who were in utero at the time of the explosion, children from Pripyat vs. other villages in the 30-kilometer zone, and children manifesting greater generalized anxiety. For both groups, children with greater Chornobyl-focused anxiety performed significantly worse than children with less Chornobyl-focused anxiety on measures of attention. The results thus fail to confirm two previous reports that relatively more children from areas contaminated by radiation had cognitive deficits compared to controls. Possible reasons for the differences in findings among the studies are discussed.

Does process-specific slowing account for cognitive deficits in Lyme disease?

Although several studies have suggested that cognitive slowing is a symptom in Lyme disease, it is not clear whether this slowing is general or relates to specific cognitive tasks. This study examined cognitive speed in 25 Lyme disease patients using a mental arithmetic task. These patients showed significant impairments when initiating the cognitive processes involved in counting, but performed as well as healthy participants (n = 23) when the number of counting increments increased. Lyme patients also performed a speeded perceptual-motor matching task as well as healthy participants. Lyme-related initiation speed deficits were significantly correlated with performance on standardized neuropsychological tests, including the Trail Making Test and the Digit Symbol Test, but not with self-reported depression. These results suggest that the cognitive deficits seen on speeded tasks are process specific in the Lyme patient group, and are not the result of generalized slowing.

Comparison of endogenous event-related potentials in attend and non-attend conditions: latency changes with normal aging.

OBJECTIVE: Endogenous event-related potential (ERP) components have been observed under both attend and non-attend conditions, but it appears that at least some of the attend and non-attend components are functionally and topographically distinct. Also, under active task conditions, motivational and attentional variations may modulate the amplitude of the ERP. These various effects of attention on the ERP can complicate comparisons of the ERPs of normal subjects with the ERPs of clinical subjects, who may have reduced attentional capabilities. The experiment reported here sought to develop a non-task paradigm that reliably produces the same ERP components typically seen under task conditions. METHODS: Using rare auditory stimuli that were discrepant from the frequent stimuli both in frequency and intensity, stimuli were presented under non-attend instructions and under instruction to count the rare stimuli. The ERPs in these two conditions were compared with ERPs in a standard oddball paradigm which used stimulus parameters comparable to those of most previous experiments on ERPs in aging. Fifty subjects, ranging in age from 20 to 77, participated. RESULTS: The ERPs to the DISCREPANT oddball stimuli under non-task conditions were similar in scalp distribution to the ERPs to the same stimuli in the ATTEND condition and to the ERPs in the STANDARD/ATTEND condition. Furthermore, there were no significant differences in the age-related increase in ERP latencies among the DISCREPANT/IGNORE, the DISCREPANT/ATTEND, and the STANDARD/ATTEND conditions. CONCLUSION: The results indicate that increases in ERP latencies with aging can be assessed in the absence of task requirements, and that the paradigm described here may prove useful in investigating cognitive processing speed in clinical populations.

Cognitive processing speed in Lyme disease.

OBJECTIVE: The goal of this study was to more precisely define the nature of the cognitive processing deficits in the patients with Lyme disease. BACKGROUND: Lyme disease has been associated with cognitive disturbances. METHOD: Sixteen patients who met the Centers for Disease Control's case definition for Lyme disease and 15 age- and education-matched control subjects completed two computerized assessments. The first was a matching procedure that assessed perceptual/motor speed. The second task was an alphabet-arithmetic (AA) test that measured the speed of mental arithmetic. On the matching task, subjects judged as true or false simple identity equations (e.g., B + 0 = B). On the AA task, subjects indicated the veracity of equations of the same form as those of the matching task but which required mental arithmetic (e.g., A + 3 = D). The use of this paradigm permits sensory or motor slowing to be distinguished from slowed cognitive processing speed. Also, the tests do not involve automated or overlearned responses. RESULTS: Lyme disease patients and healthy controls did not differ in perceptual/motor speed. However, Lyme disease patients' response times were significantly longer than those of healthy controls during the AA task, demonstrating specific impairments in mental activation speed. CONCLUSIONS: These results suggest that Lyme disease patients show specific deficits when initiating a cognitive process. These impairments are independent of sensory, perceptual, or motor deficits.

Event-related potentials to inspiratory flow-resistive loads in young adults: stimulus magnitude effects.

Event-related potentials were recorded to brief presentations of four levels of inspiratory flow-resistive loads in young adults. We labeled the loads according to the level of resistance they provided subjectively: sub-threshold (0.34 cmH2O/l per s), near-threshold (4.01 cmH2O/l per s), intermediate (10.4cmH2O/l per s), and near-occlusion (57.5 cmH2O/l per s). No discernible ERPs were elicited by the undetected, sub-threshold stimulus but late components of the ERP (P2, N2, and P3) were observed to each of the three larger stimuli. They were related, in part, to behavioral judgments obtained during the stimulus periods. Both the latency and amplitude of the ERP components varied systematically as a function of stimulus magnitude, in a manner comparable to that observed in ERP paradigms using auditory and visual stimuli. Thus, the data show that event-related potentials to breathing are sensitive to physiologic effects of resistive loads present at the onset of inspiration. Respiratory ERPs may be used to infer sensory and perceptual responses to increases in airflow resistance and, accordingly, may relate to the perception of airflow obstruction in patient populations.

Many-valued logic and event-related potentials.

In previous experiments on event-related potentials (ERPs) during linguistic judgments, the subjects' decisions have been categorical (e.g., true vs false). In this experiment, more realistic variations in truth value and subject certainty were used. Thirty-eight naive undergraduates read a story about a fictional murder. ERPs were recorded as the subjects rated the strength of their beliefs about statements relating to suspects in the crime. Because no subject was sure which of the suspects was guilty of committing the crime, binary (true-false) category judgments were inappropriate. Three components of the ERP waveforms were affected by the experimental manipulations. An early positive component was largest to sentences concerning the suspect considered most likely to have committed the crime. A subsequent broad posterior positivity (LPC) also showed significant sentence-type differences, but it was larger to sentences considered probable--whether they were true or false--than to more ambiguous sentences. A third ERP component (N400) was negative at midline electrode sites and peaked at approximately 420 ms. Subjects' truth-value judgments had no effect on the N400. N400 was, however, affected by the subject's task. It was more negative when subjects made graded judgments about truth value than when they made binary true-false judgments. Overall, naturalistic judgments of sentence validity produced a variety of brain responses that reflected different aspects of linguistic decision making.

Phonological processing and the role of strategy in silent reading: behavioral and electrophysiological evidence.

To examine the contribution of phonological processing in silent reading, 51 native English speakers made decisions about targets presented either in word pairs or in sentences. The target words were homophonically (plain-plane), orthographically (plane-place), or semantically (plane-jet) related. N200 was enhanced only to homophonic targets, suggesting the use of phonological information in silent reading. Memory load did not affect the N200 amplitude. N400 was enhanced to all semantically incongruent words and was larger in the word pair condition. Reaction times were influenced by both experimental condition and target relationships; homophonic stimuli elicited the fastest RTs in the word pair condition and the slowest RTs in the sentence condition, suggesting the use of different strategies. Thus, ERP components and behavioral responses registered different aspects of language processing.

Auditory evoked potentials in multiple sclerosis: correlation with magnetic resonance imaging.

The present study addresses issues regarding the location of neural sources (i.e. generators) of human auditory evoked potentials (AEPs), and the pattern of neural conduction in the auditory pathway. AEPs were recorded from fifteen patients with multiple sclerosis (MS) and compared to normals. The recordings included auditory brainstem responses (ABRs), mid-latency responses (MLRs), and long-latency responses (LLRs). AEP latency abnormalities were related to the locus of demyelinating lesions, as determined by magnetic resonance imaging (MRI) scans. The data demonstrated several anatomical patterns relating abnormal ABR wave intervals and abnormal MRI signals. From these patterns specific loci for ABR neural sources in the brainstem might be postulated. In addition, the earlier the ABR waves, the more unilateral the abnormalities appeared, suggesting bilateral sources for later waves. The MLRs were highly correlated with ABR wave V and were associated with greater abnormality in MRI signals in midbrain and forebrain regions. In general, patients with abnormal LLRs also had widespread AEP and MRI abnormalities, supporting a multiple source approach for the N1 wave of the LLRs. The observation that LLRs were only abnormal in the presence of bilateral ABR abnormalities suggests a cross wiring which would serve as a compensatory mechanism for unilateral disturbances. The AEP data showed dissociation between early and late wave abnormalities, thus supporting parallel channels for neural conduction in the central auditory system. Such a model calls for some degree of independence of AEP generators along the auditory pathway.

ECT and non-memory cognition: a review.

The literature on the effects of electroconvulsive therapy (ECT) on non-memory cognitive functions is reviewed. It is concluded that with early methods of ECT administration (sine wave, high dose), these effects are larger than those of depression. They are less pronounced, and usually do not exceed the effects of depression, when modern methods of ECT administration (brief pulse, moderate or low dose) are used. Following ECT, these functions progressively improve. At one week to seven months after ECT, performance is better than before ECT, probably because of the alleviation of both the effects of depression and of ECT. The time course to full recovery of the non-memory effects resembles that of the recovery of amnesic effects, although the latter are more pronounced. With bilateral ECT, as with right unilateral ECT, there is evidence that right hemisphere effects are more pronounced. The results of this review argue that clinicians should take the non-memory cognitive effects of ECT into account, and patients should be informed of their existence before they sign consent for ECT.

Construct validity in the Trail Making Test: what makes Part B harder?

The Trail Making Test (TMT) is primarily a test of motor speed and visual attention. In Trail Making, Part A, the subject's task is to quickly draw lines on a page connecting 25 consecutive numbers. In Part B, the subject must draw the lines alternating between numbers and letters. To determine what makes Part B harder than Part A, variations of the standard Trail Making Test were assessed. Forty college students (20 male, 20 female) were given four forms of the Trail Making Test. The results show that Trail Making, Part B with just numbers took longer to complete than the standard Part A with numbers. Part B is 56 cm longer and has more visually interfering stimuli than Part A. These results indicate that Part B is more difficult than Part A not only because it is a more difficult cognitive task, but also because of its increased demands in motor speed and visual search.

Event-related potentials to airway occlusion in young and old subjects.

Event-related potentials (ERPs) were recorded to both inspiratory and expiratory airway occlusion in young (21-28 years) and old (55-67 years) subjects under both attend and ignore conditions. Early and late components of the ERP (N1, P2, N2, P3) were observed to both types of occlusions in both conditions. Variations in these components were consistent in both direction and degree with those observed in oddball tasks employing exteroceptive stimuli. ERPs for breathing may serve to clarify sensory attributes of respiratory stimuli in humans and to identify central processing abnormalities in patient populations.

An estimate of the prevalence of drug misuse in Liverpool and a spatial analysis of known addiction.

BACKGROUND: The objective of this study was to determine the prevalence and distribution of opiate and cocaine misuse in the City of Liverpool in 1991. The databases included residents of the city using opiates or cocaine, who were known to the Drug Dependency Units or the Infectious Diseases Unit, or who were arrested for possession of drugs in 1991. METHODS: A three-sample log-linear capture-recapture method was applied to databases containing details of drug users with City of Liverpool postcodes, to determine the prevalence of drug misuse in 1991. Linear regression analysis was performed to correlate the prevalence of known drug misuse with indices of material deprivation in each electoral ward. RESULTS: Data on 1427 individuals were analysed, producing an estimate of the drug-using population of 2344 [95 per cent confidence interval (CI) = 1972-2716] and a period prevalence of 5.2 per 1000 [95 per cent CI = (4.5-6.0) per 1000]. In the 15-29 year age group, the prevalence of drug abuse was 16.9 per 1000 [95 per cent CI = (13.9-19.9) per 1000]. There was a negative interdependence between the police and Drug Dependency Unit databases with attenders at the Unit being 7.2 (95 per cent CI = 4.6-11.4) times less likely to be arrested for possession than non-attenders. There was a strong correlation between the distribution of known drug use and material deprivation, as measured by the Townsend index (r = 0.75; p < 0.001). CONCLUSIONS: The capture-recapture method allows the prevalence of drug misuse to be estimated and provides more meaningful information than is available from the notification system. The study suggests that people in contact with drug services are less likely to commit crimes of possession of class A drugs than those not in contact with drug services. There is a strong association between drug abuse and deprivation, and therefore the purchasing of services for drug misusers should be focused on areas of deprivation.

Psychophysical measures of central auditory dysfunction in multiple sclerosis: neurophysiological and neuroanatomical correlates.

Central auditory function was assessed in 15 patients with multiple sclerosis (MS) to determine whether the demyelinating lesions resulted in disruption of temporal processing. Auditory evoked potential (AEP) recordings included all three latency regions: Auditory brain stem responses (ABRs), midlatency responses (MLRs), and long-latency responses (LLRs). Two psychophysical tasks thought to involve temporal processing were used: a monaural-processing task (gap-detection) and a binaural-processing task (masking level difference; MLD). Further, AEP abnormalities and psychophysical performance deficits were related to lesion location, based on magnetic resonance imaging (MRI) scans. Reduced MLDs were seen in six MS subjects. Abnormal MLDs were always accompanied by abnormal ABRs and MLRs, and compared to subjects with normal MLDs, the subjects with abnormal MLDs were more likely to have bilateral abnormalities in the AEPs. Further, MLR indices of abnormal binaural interaction appeared to be specifically related to the psychophysical measure of binaural processing. The MRI data of these patients indicated widespread involvement of the auditory pathway. MS subjects with abnormal MRI signals restricted to levels caudal to the lateral lemniscus did not have abnormal MLDs. Gap-detection thresholds were more resistant to the effects of the demyelinating lesions; only two subjects had abnormal gap-detection thresholds. These subjects had extensive AEP abnormalities (bilaterally, in all three latency regions). The gap-detection thresholds were most specifically related to abnormalities of the LLRs. In addition, the subjects with elevated gap-detection thresholds were the only ones with a prolonged interval between the ABRs and MLRs. Thus, efficient neural conduction between the upper brain stem and auditory cortex appears to be crucial for normal monaural temporal processing. The results indicate that demyelinating lesions can cause deficits in temporal processing in the central auditory pathway. However, auditory temporal processing is not a unitary phenomenon since abnormalities at different levels of the auditory system disrupt different types of temporal processing. Finally, abnormal psychophysical performance was not seen in all subjects with AEP and MRI evidence of involvement of the auditory pathway; rather, these psychophysical measures appeared to be sensitive to disruption only in specific portions of the auditory system.