Abstracts

Association between Quantitative EEG and Neurocognition in Methamphetamine Dependent Volunteers

Newton TF, Kalechstein AD, Hardy DJ, Cook IA, Nestor L, Ling W, Leuchter AF

UCLA School of Medicine. Los Angeles, CA, USA

Objectives: Methamphetamine administration is associated with long-lasting reductions in markers for dopaminergic neurons in preclinical models and in humans. These changes may be associated with alterations in brain electrical activity and in cognition.

Methods: The sample included 11 methamphetamine dependent subjects and 11 non-drug using volunteers. Methamphetamine dependent subjects were hospitalized for 4 days to document abstinence; non-drug using volunteers were studied as outpatients. EEGs were recorded in the eyes-closed resting state, and absolute EEG power in each frequency band (0.5–4 Hz, 4–8 Hz, 8–12 Hz, and 12–20 Hz) was measured using a fast Fourier transform. EEG power was log-transformed prior to analysis. Cognition was measured using computerized reaction time tasks in 9 volunteers from the methamphetamine-dependent group and 10 from the control group; 3 participants declined to complete the cognitive tasks.

Results: Methamphetamine dependence was associated with increased EEG power in the delta and theta bands. ¹ Power in the alpha and beta bands did not differ between the groups. Within the methamphetamine dependent group, a majority of the conventional EEGs were abnormal (64%), compared to 18% in the non-methamphetamine using group. Within the methamphetamine-dependent group only, increased theta QEEG power correlated significantly with reaction time on tasks that were more difficult or that were degraded by fatigue. Increased theta QEEG power also correlated with reduced accuracy on a working memory task.

Conclusions: Increased QEEG power in the theta band is associated with worse performance on reaction time tasks in the methamphetamine dependent sample but not in the non-drug using volunteers. Significance: Methamphetamine dependence is associated with pathological alterations in brain electrical activity and in cognitive performance. QEEG appears to provide a sensitive measure of methamphetamine-associated alterations in brain function.

The Transcranial Magnetic Stimulation for Diagnosing and Treating Patients in Coma and Vegetative State

Gimranov RF, Maltceva EA, Kurducova EN

Peoples Friendship University of Russia - Medic's Retraining Faculty Moscow, Russia

Introduction: Sometimes the cycle of sleeping and awakening can be recovered in patients in coma (C), and patients can open their eyes periodically. This situation can be referred to as the vegetative state (VS). We studied the possibilities of using TMS for diagnosis and treatment of patients in C and VS.

Methods: We studied 30 patients in C and 45 in VS. Patients in VS were treated by complex TMS and electric stimulation (ES) of median nerves. The stimulation was given for 3–6 hours every day (10 days). Induction of magnetic field was 1.6–2.2 TI, frequency was 5–15/sec. Neurophysiological and clinical evaluations were performed by investigating changes of EEG, SSEP, VEP, BAEP, MEP, Glasgow Coma Scale and concentrations of cathecholamines.

Results: After complex stimulation there were indications of decrease in latency and increase in amplitude of the P100 VEP, P23 SSEP, P300, MEP or their appearance (if they were absent before). The level of dopamine statistically approached normal after complex stimulation. Glasgow's index after stimulation increased to 11.3+1.9 (before 8.8+1.6).

Conclusions: From this process we can evaluate the motor system by using TMS in patients in C and VS. Complex stimulation (TMS+ES) of patients in VS leads to positive changes in the sensorimotor, motor, and visual cortex and leads to changes in concentrations of dopamine in blood and an increase in the Glasgow's index.

The Prediction of Response to Treatment with Standard and New Antipsychotics

Silvana G, Paola B, Armida M

University of Naples SUN Naples, Italy

Introduction: Several independent groups have reported a relationship between the increase of QEEG alpha activity during neuroleptic treatment and a favourable clinical response to the treatment with these drugs. ² Our group found that changes in the slow alpha range, observed six hours after the administration of a single test dose of either haloperidol or clopenthixol, discriminated between R and NR, with an accuracy rate of 88.9% (91.3% in chronic and 84.6% in first episode patients).

Methods: More recently we used the test dose procedure to test the hypothesis that changes in the slow alpha range also predict the response to novel antipsychotics. Clozapine or risperidone were administered to 18 drug-free patients with DSM-IV schizophrenia.

Results: Three patients were responders and 5 were nonresponders to treatment with risperidone, while 5 were responders and 5 nonresponders to clozapine. QEEG findings indicate that, in line with what was observed with standard neuroleptics, changes in the slow alpha band discriminates responders from nonresponders to risperidone. For clozapine the same pattern of QEEG changes (increase of theta and decrease of fast alpha and beta activity) was observed in both responders and nonresponders.

Conclusions: The results confirm the validity of the test dose slow alpha changes in the prediction of response to treatment with standard neuroleptics and suggest its utility in the prediction of response to risperidone. Our preliminary findings seem to indicate that traditional parameters used by pharmaco-EEG studies are not useful in the prediction of response to clozapine.

Emotional Processing in Subjects with Panic Disorder

Silvana G, Armida M, Paola B, Eleonora M, Mario M

University of Naples SUN Naples, Italy

Introduction: Subjects with Panic Disorder (PD) have high scores on alexithymia, a tendency to interpret ambiguous stimuli as threatening and an attentional bias toward threat-related cues. Several findings suggest that a dysfunction of temporo-lim-bic regions, in particular those of the right hemisphere, involved in emotional processing, might underlie these characteristics.

Methods: Alexithymia was evaluated by the Toronto Alexithymia Scale in 17 drug-free patients with DSM-IV PD and matched healthy controls (HC). In all subjects ERPs were recorded from 30 channels during a visual target detection task, in which stimuli with different emotional valence (neutral, erotic, threat-related and phobic) were used as distractors. The Low Resolution Electromagnetic Tomography (LORETA) was used to identify cortical generators of the ERP P3a component for distractors.

Results: Alexithymia was more frequent in PD subjects than in HC. Comparison between erotic and neutral distractors revealed a different pattern of activation in HC and PD subjects: an activation of the anterior cingulate, insula and medial frontal areas was observed in HC, while a reduced activation of the right parieto-temporal regions was found in PD subjects. In HC no difference in activation patterns was found when comparing threat-related and neutral stimuli, while in PD subjects a reduced activation of right temporal regions was observed when the same comparison was performed.

Conclusions: The results confirm the presence of a reduced activation of right hemisphere integrative areas during emotional stimuli processing in subjects with PD.

Mismatch Negativity: Basic Neurophysiology and Findings in Schizophrenia

Salisbury D, Harvard Medical School/McLean Hospital, Belmont, Massachusetts, USA

Molholm S, Nathan Kline Institute, Orangeburg, New York, USA

Korzyukov O, Yale University School of Medicine/West Haven, Connecticut, USA

McCarley RW, Harvard Medical School/Brockton, Massachusetts, USA

Mismatch negativity (MMN) is an event-related brain potential associated with the pre-attentive detection of stimulus deviance. Recently, MMN has been studied as a measure of echoic memory in schizophrenia. Interestingly, MMN appears to be normal during the early stages of schizophrenia and to get progressively worse. Hence, MMN may serve as a physiological index of brain changes in schizophrenia. The purpose of this symposium is to examine the basic electrophysiology of MMN, including techniques and paradigms, the putative brain generators of MMN, fMRI studies of MMN, and MMN findings in chronic and first-episode schizophrenia patients, with reference to underlying cortical generator volumes. The objectives of the course are to familiarize researchers with the current state of knowledge in MMN research, and to provide them with the ability to perform new studies of MMN.