Edward L. Reilly

P300 event-related potential amplitude and impulsivity in cocaine-dependent subjects.

Previous studies report reduced amplitude of the P300 event-related potential in cocaine-dependent individuals. Cocaine dependence is also associated with increased impulsivity, possibly due to deficits in cognitive function that are associated with reduced P300 amplitude. In the current study, the relationship between cocaine dependence, impulsivity, and P300 amplitude were examined. An auditory oddball event-related potential task along with self-report (Barratt Impulsiveness Scale version 11) and behavioral laboratory (Immediate and Delayed Memory Task) measures of impulsivity were assessed in healthy controls (n = 14) and subjects who met DSM-IV criteria for current cocaine dependence (n = 17). P300 amplitude was reduced and self-reported and behavioral laboratory impulsivity scores were elevated among the cocaine-dependent group compared to controls. There was a positive correlation between the questionnaire and behavioral laboratory measures of impulsivity, and a negative correlation between impulsivity measures and P300 amplitude. The correlation between self-reported impulsivity scores and P300 amplitude remained after taking into account the number of childhood conduct disorder symptoms. This study supports the hypothesis that the basic neurophysiology responsible for the P300 amplitude in cocaine-dependent individuals is associated with impulsivity independent of a history of childhood conduct disorder symptoms.

A Multichannel Signal Processor for the Detection of Epileptogenic Sharp Transients in the EEG

A high-speed multichannel signal processing system is described which is capable of performing automated detection of epileptogenic sharp transients (ST) in the electroencephalogram (EEG). The system is implemented with individually programmable microprocessors on the input channels, followed by a single-board microcomputer which correlates results obtained from each channel, and can process data played back from a tape recorder at a speed eight times the realtime recording speed. A multichannel correlation algorithm is used to enhance the performance of the system in the presence of muscle artifact (EMG). Results are presented showing that the multichannel correlation is capable of reducing, in some cases, both missed detections due to poorly defined STs and false alarms due to EMG.

Accelerated mental aging in alcoholic patients

Discriminant function and polynomial regression methods were used to define a mental age function from scale score profile patterns found in the WAIS manual. Values on the mental age function then were calculated from WAIS scale score profiles for 164 alcoholics in the age range 35 to 74. Validity of the mental age function was evident in clear discrimination between chronological age groups in the alcoholic sample. As compared with WAIS normative values for the mental age function, the mean mental age for patients in the alcoholic sample was advanced approximately 7 years over age-matched normals. Unweighted means ANOVA revealed the accelerated mental aging of alcoholic patients to be statistically significant. This finding is discussed in the context of other research that supports a premature aging hypothesis.

General and specific locus of control in cocaine abusers

Although the struggle for control has been widely recognized as a central feature of addiction, information about its role in the development and maintenance of addictive behavior is limited. This study compared general and specific locus of control in three groups of cocaine abusers: (a) hospitalized subjects with no prior treatment experience, (b) hospitalized subjects with prior treatment experience, and (c) recovering cocaine abusers. Results of initial analyses of variance revealed significant group differences on both general and specific scales. Scores of recovering cocaine abusers were more internal than those of hospitalized subjects. Differences on the general scale were not significant when age was controlled. No significant differences were noted between the two groups of hospitalized subjects, but scores of hospitalized cocaine abusers made an internal shift over the course of treatment. These findings support generalizability of models previously applied to alcoholics and suggest that internality is positively correlated with recovery.

Reliability of rapid clinical staging of all night sleep EEG.

The recording of all night sleep EEGs on a portable cassette recorder, and the rapid visual staging of the sleep records at 20 times real time, represent innovations in sleep research methodology. The reliability of sleep stager percentages obtained in this way is examined in this article. In the first of two studies, all night sleep records for six individuals were each staged twice by each of two qualified electroencephalographers. Inter-rater and intra-rater reliability assessed by intraclass correlation methods was modest, requiring the averaging of results from two judges to reach acceptable levels. Following consistency training, the two electroencephalographers staged all night sleep records for six additional subjects. Acceptable reliability was achieved in measurement of stages 2, 3, 4 and REM, although difficulty in reliably distinguishing stage 1 from the awake stage persisted. On the basis of these results, rapidly paced visual interpretation of sleep records at 20 times real time is recommended as a feasible way of meeting demands imposed by innovations in the technology of recording sleep EEGs.

Photic driving and psychogeriatric diagnosis.

The electroencephalogram is a widely used instrument in distinguishing between dementia and functional disturbance in the elderly. The EEG changes that accompany pathological senility are the slowing of the dominant posterior rhythms, and increases in theta and delta range activity. 1,2 Early in the clinical course of presenile or senile dementia, however, the EEG may be entirely normal. This is possibly due to a lag of the electroencephalographic findings in relation to the clinical signs and symptoms of the diseases. Alternatively, this could be secondary to undetected slowing in the EEG that does not go below accepted alpha range limits. There is also good evidence that some neuropathological subtypes of dementia (Picks Disease) have little effect upon the EEG. These difficulties in early EEG diagnosis of dementia parallel the difficulties of the clinician. For it is early in the clinical presentation of an organic brain syndrome, that the problem of a pseudodementia or a functional disturbance, presenting with the cognitive and emotional symptomatology more typical of a dementing process, so frequently occurs. Likewise, the earliest presentation of dementia proper can be depression or other more typical functional signs and symptoms. 3,4 An electrographic parameter that may be more sensitive in discriminating functional from organic disorders is the non-convulsive cerebral response to intermittent photic stimulation (photic driving). Kooi 5 showed that in general the photic driving response was reduced in all types of neurological pathology, including diffuse cerebral disease associated with dementia. Coull and Pedley 6 recently reported that it was the development of the photic response in terms of frequency, that best correlates with lateralized cerebral pathology. Hamel et at.,? using the compressed spectral array, showed that the quantified photic driving response in both its fundamental and harmonic components was directly related to the degree of encephalopathy produced by renal failure, and highly correlated with slowing in the same patients. In functional conditions, Ulett et al.8 reported that the amount of driving, especially at higher flash frequencies or at higher harmonics, was correlated with anxiety and susceptibility to stress. Klaiber et al.9 reported that depressed women had significantly increased amounts of driving to photic stimulation than age matched non-depressed women. The subject of this study is to see if this reported divergence in photic driving between functional and organic disorders could be used to better discriminate between functional and organic psychiatric conditions in the elderly.

Measurement of locus of control in cocaine abusers

Although the course of recovery for cocaine abusers is particularly problematic, there has been little investigation of perceptions of control in this population. The purposes of this study were (1) to develop an instrument that would measure specific expectancies of control in cocaine abusers, and (2) to examine the relationship between specific and generalized expectancies of control in these subjects. Rotters I-E scale and a modification of the Drinking-Related Locus of Control (DRIE) scale were administered to 40 cocaine abusers in their first week of treatment. The Modified DRIE scale demonstrated adequate internal consistency and satisfactory test-retest reliability in the sample. No significant correlation was found between the Modified DRIE scale and the I-E scale, probably because of the relatively small sample size. Further validation of the Modified DRIE scale is indicated.

Failure of Pavulon to Consistently Provide Adequate EMG Attenuation for Recording Electrocerebral Inactivity

It is important for the electroencephalographer to consult regularly and closely with the clinician ordering EEGs. This is particularly true in the relatively specialized area of recording for confirmation or support of the clinical impression of brain death. In the instances when a record is being run primarily to confirm the absence of electrocortical activity, it is clearly possible that artifact may be so high in the recording that such a determination is difficult or impossible. A particular artifact of concern is that of persisting muscle potential. As demonstrated in the cases above, this can be promptly eliminated with the use of the muscle relaxant succinylcholine chloride (Anectine). Often the use of pancuronium bromide (Pavulon) at a level that causes an equal clinical relaxation, leaves residual electrical muscle potentials that continue to make interpretation of the EEG difficult, if not actually impossible with any degree of certainty.

EEG, ALCOHOL, AND ALCOHOLISM

Publisher Summary Electrophysiological sleep studies may provide clinically useful information for separating primary depressive illness from alcoholism. Separation of primary depression from alcohol abuse or dependence from primary alcoholism with depression is a formidable task. The presenting alcoholic almost invariably has a sleep disturbance, appetite disturbance, dysphoric mood, loss of interest in sex, and often has suicidal ideation. Available electrophysiological tests include electroencephalogram (EEG), the pattern-reversal visual evoked potential, the short-latency auditory brainstem evoked potential, and long- and short-latency somatosensory evoked potentials. Clinically significant abnormalities in these tests should be considered evidence of neurological dysfunction secondary to the neurological complications associated with alcoholism or another neuropathological process. Sleep studies, long-latency evoked potentials, and digital-frequency EEG analysis all show protracted significant changes in the recovering alcoholic. A knowledge of the specific types of EEG changes seen in withdrawal, alcohol withdrawal delirium, and other syndromes associated with alcoholism, when integrated with other clinical data, makes routine EEG valuable to the clinician in specific cases.

EEG AND PSYCHOTROPIC DRUGS

Publisher Summary This chapter focuses on electroencephalogram (EEG) findings to illustrate changes in the central nervous system (CNS) function produced by psychotropic medications. The EEG is used in two quite distinct ways in the study of medication effects. The computer analysis of the EEG activity demonstrates combinations of changes in the different frequency bands, which has proved useful in comparison of different compounds and subsequent identification of new compounds of potential clinical value. The computer analysis of acute drug effects should be recognized as quite different from the EEG changes expected in a patient routinely taking these medicines and the changes seen in visually interpreted EEG, read by clinical standards without serial record comparisons. In visually interpreted EEGs, chronic use of neuroleptic and antidepressant drugs has relatively little effect on the EEG, except when they have a hypnotic effect, which changes the level of consciousness or when they have a toxic effect producing the expected changes of toxicity.