Topographic mapping of EEG and auditory evoked P300 in neuropsychopharmacology (topographic pharmaco-EEG and pharmaco-AEP 300)

Auditory and visual P300 reflecting cognitive improvement in patients with schizophrenia with quetiapine: a pilot study

We recorded event-related potentials (ERPs) in patients with schizophrenia before and after treatment with quetiapine, to investigate this drug's effects on cognitive function. Auditory and visual oddball stimulus discrimination paradigms were presented to patients with schizophrenia (N=20) before and after 3months' treatment with quetiapine. The 2-stimulus auditory oddball paradigm used a standard tone (1000Hz, 75dB, 80%) and a target tone (2000Hz, 75dB, 20%). The 2-stimulus visual oddball paradigm used a standard stimulus (small circle, 80%) and a target stimulus (large circle, 20%). Patients' severity of psychopathology was initially evaluated with the Positive and Negative Syndrome Scale (PANSS) and was likewise re-evaluated after treatment. After treatment with quetiapine, patients' P300 amplitudes increased over baseline for both tasks (auditory stimuli, P<0.01; visual stimuli, P<0.01) and their P300 latencies for both target stimuli decreased significantly (auditory stimuli, P<0.001; visual stimuli, P<0.01). Visual P300 amplitude was negatively correlated with the severity of positive symptoms at the Fz electrode before the treatment (r=-0.45, P<0.05). After treatment with quetiapine, there were no significant correlations between severity of positive or negative symptoms and visual P300 amplitudes for midline electrodes. These findings suggest that the reduced and delayed P300 may be a state marker for schizophrenia, which may in turn be modulated by positive symptoms, and also suggest that the amplitude and latency for both auditory and visual tasks may be decreased by quetiapine treatment. Based on these results, we suggest that the atypical antipsychotic quetiapine may improve some aspects of cognitive domains in patients with schizophrenia.

Brain electrical activity mapping of EEG for the diagnosis of (sub)clinical hepatic encephalopathy in chronic liver disease

We studied the role of brain electrical activity mapping (BEAM) in the assessment of neuropsychiatric disturbances in 48 cirrhotic patients without clinical evidence of hepatic encephalopathy (no HE, n = 19), with subclinical HE (grade 0, denoting pathological psychometric tests, n = 13) and mild-to-moderate HE (grade I, n = 6; grade II, n = 10). Results were compared with 23 healthy controls. BEAM variables quantified were: (i) the peak frequency (PF); (ii) the amplitude of PF; and (iii) the topographic localization of the maximum peak amplitude digitized for quantification by using a coordinate system. Mean amplitudes and their topographic localization in the following frequency-bands were analysed: delta (1.0-3.5 Hz), theta (4.0-7.5 Hz), alpha 1 (8.0-9.5 Hz), alpha 2 (10.0-11.5 Hz), beta 1 (12.0-15.5 Hz), beta 2 (16.0-19.5 Hz), and beta 3 (20.0-23.5 Hz). The PF was significantly slower in all HE patients than in healthy controls (8.5 +/- 2.0 Hz v. 10.1 +/- 1.0 Hz, P< 0.001). Even in no HE, the PF was significantly slower than in controls (8.6 +/- 1.5 Hz v. 10.1 +/- 1.0 Hz, P< 0.01). No relevant topographic differences of PF were observed. The mean amplitudes of the following bands differed significantly between controls and patients: theta (increased in HE, P< 0.05), alpha 2 (decreased in HE, P< 0.05), and beta 2 and beta 3 (increased in HE, (P < 0.05). In HE patients, the topographic localization of all beta bands showed a significant shift from parieto-occipital areas to central areas of the cortex. We conclude that BEAM is a sensitive tool for detecting neuropsychiatric disturbances in cirrhotics with no HE and with subclinical HE. The combination of PF in the theta band, increased mean amplitude in the beta 2 band, and the localization of the latter band in the frontocentral area of the cortex is an objective and sensitive tool for identifying neuropsychiatric disturbances in 85% of cirrhotic patients with no HE. Further studies are required to determine the clinical implications of these abnormal findings in the absence of overt clinical symptoms.

Substance use disorder exacerbates brain electrophysiological abnormalities in a psychiatrically-ill population

OBJECTIVE

To assess by brain electrical activity mapping whether cocaine and alcohol abuse and dependence would exacerbate electro-physiological abnormalities in a psychiatrically-ill population.

DESIGN, SETTING, AND PARTICIPANTS

Utilizing a brain mapping system, we assessed EEG, Spectral Analysis (Quantitative EEG[QEEG]). Evoked Potentials (Auditory and Visual), and P300 (cognitive evoked potential), in a total of 111 probands divided into three groups: controls (N = 16), psychiatrically-ill without comorbid substance use disorder (N = 34), and psychiatrically-ill with comorbid substance use disorder (cocaine and alcohol abuse and dependence) (N = 61), at an outpatient neuropsychiatric clinic. With regard to demographic data, the group participating in this study did not differ significantly. A comparison was made among the groups to assist in differentiating the effects of substance use disorder compared to psychiatric disease on brain electrical activity.

MAIN OUTCOME MEASURES

An assessment of electrophysiological abnormalities and their brain location in psychiatric and substance use disorder patients was done with a brain electrical activity mapping test.

MAIN RESULTS

Among the non-substance use disorder, psychiatrically-ill (PI) and substance use disorder, psychiatrically-ill (PI/SD) groups, significantly different brain map abnormalities were observed relative to an assessed normal population MANOVA (P = .017). Moreover, with regard to Spectral Analysis, ANOVA was significant at a P = .038, and we found a weighted linear trend of increased abnormal total spectral analysis (P = .0113), whereby substance use was significantly worse than controls. Moreover among the PI and PI/SD groups, significantly greater total evoked potential (EP) brain trap abnormalities were observed when compared with a characterized normal population (P = .0023) with increasing abnormalities as a function of substance use disorder as measured by a weighted linear trend (P = .0022). In order to determine the site of the EPS abnormalities, we evaluated these abnormalities by location. In this regard, we found all temporal abnormalities (AVBITA, see Table 2) among the PI and PI/SD groups to be significantly greater relative to an assessed normal population (P = .0026). Furthermore, we observed a linear trend of increased temporal abnormalities with increasing substance use disorder (P < .0008). In terms of bitemporal abnormalities (AVBIT) among the PI and PI/SD groups, we also found significantly more bitemporal lobe abnormalities in the PI/SD group compared to our control population (P = .009). Additionally, a weighted linear trend of increased abnormal bitemporal lobe abnormalities was observed with increasing substance use disorder (P = .0022). In the frontal lobe similar findings were observed. With AVBIFA the ANOVA was P < .011, with a weighted linear trend of P < .005 and the PI/SD group were significantly more abnormal than PI or CS on a Duncan Range test. It is noteworthy that in a selected group of depressed (Major Depressive Disorder Recurrent, 296.3) patients, we found profound abnormalities in the various brain map parameters tested. MANOVA and Univariate ANOVA's revealed significantly greater abnormalities in the PI and PI/SD groups compared to assessed controls. A MANOVA for total brain abnormalities was significant at P = .043 and univariate ANOVA's for composite measurements of TSA (P = .017), EPS (P = .0002), AVBITA (P = .000015), and AVBIT (P < .00002) are also significant. With regard to EPS and AVBITA a weighted linear trend was observed where there were increasing abnormalities with increasing substance use disorder, P = .0001 and P = .000003, respectively. Most importantly we found that in addition to increased abnormalities with increasing substance use disorder the PI/SD group had significantly more abnormalities compared to the PI group with regard to both the TSA (P < .05) and AVBIT (P < .05) composite parameters as meas

Topographic electroencephalogram of propofol-induced conscious sedation

OBJECTIVES

To determine the effects of increasing doses of propofol that induce conscious sedation on the topographic electroencephalogram (EEG) of human volunteers and to test the hypothesis that more frontal brain areas are affected by low doses of propofol.

METHODS

The scalp EEG was recorded monopolarly from 16 different sites based on the 10-20 International System. Microcomputer-based hardware and RHYTHM 7.1 software were used to obtain quantitative power frequency topographic EEG data. A total of 10 normal adult volunteers were given incremental doses of propofol targeted to plasma concentrations of 0 to 1200 ng/ml.

RESULTS

Sedative concentrations of propofol produced a dramatic increase in beta 1, an increase in alpha 2 and beta 2, and an increase in delta activity at the largest concentration, with almost no change in theta activity. The increase in beta 1 activity had a linear correlation with plasma propofol levels (r = 0.9). Topographic mapping indicated that beta 1 activation was primarily in the frontal and central regions, with focal changes more in the left hemisphere.

CONCLUSIONS

Topographic brain EEG mapping techniques indicate that frontal brain beta 1 EEG activity may be useful as an objective brain index of propofol conscious sedation.