Topographic analysis of EEG photic driving in patients with schizophrenia following clozapine treatment

An Exploratory Study of Intensive Neurofeedback Training for Schizophrenia

Schizophrenia is a chronic and devastating brain disorder with ongoing cognitive, behavioral, and emotional deteriorated functions. Neurofeedback training, which enables the individuals to regulate their brain activity using a real-time feedback loop, is increasingly investigated as a potential alternative intervention for schizophrenia. This study aimed to explore the effect of short but intensive neurofeedback training for schizophrenic patients with difficulty for long-time training. A middle-aged woman with chronic schizophrenia completed the intensive training of alpha/beta2 (20–30 Hz) in four consecutive days with a total training duration of 13.5 hours. The results showed that her alpha/beta2 increased over sessions, and her behavior performance including short-term memory, mood, and speech pattern was improved at the end of neurofeedback training. Importantly, a 22-month follow-up found a dramatic improvement in both positive and negative symptoms. These positive outcomes suggest that such intensive neurofeedback training may provide new insight into the treatment of schizophrenia and thus deserves further study to fully examine its scope.

Sequential EEG Analysis during Intermittent Photic Stimulation in Never-Medicated Patients with Schizophrenia

To investigate sequential changes in electroencephalograms (EEGs) during intermittent photic stimulation (IPS), quantitative EEG analysis for the alpha band (related to stimulus frequency) was performed in 18 drug-naïve schizophrenic patients and 18 sex- and age-matched control subjects. IPS consisted of white flickers at 10 flashes/sec, lasting 10 sec and repeated six times at 10 sec intervals. The differences between the two groups were assessed for two conditions (i.e., during photic stimulation (PS) and inter-PS). During stimulus, the absolute 9–11 Hz band power of the patient group was higher at the posterior than that at the anterior sites throughout the 10 sec periods. However, this difference between sites was not seen during the first 1 sec in the control group. During the nonstimulus period, posterior dominance of 9–11 Hz band power was prominent in the patient group throughout. In the control group, however, this difference was minor, especially during the latter half of the period. These results suggest that schizophrenic patients show fewer changes in posterior alpha activity during both stimulus and nonstimulus, and this continuity of posterior dominance may reflect hyperarousal, which counteracts any decrease in vigilance throughout the IPS.

Double-blind, randomized sham controlled study of deep-TMS add-on treatment for negative symptoms and cognitive deficits in schizophrenia

Negative symptoms and cognitive deficits are considered core symptoms of schizophrenia, yet treatment for them remains inadequate. Deep-transcranial magnetic stimulation (TMS) is a novel technology that enables non-invasive stimulation of deep layers of the prefrontal cortex. Preliminary evidence suggests that deep-TMS could be effective in the treatment of negative symptoms and cognitive deficits. The current study is the first double-blind, randomized sham-controlled study to examine the feasibility of deep-TMS add-on treatment for negative symptoms and cognitive deficits in schizophrenia. Twenty daily H1 deep-TMS treatments (20Hz, 120% MT) were delivered, in a double-blind, randomized sham-controlled design (n=30). Extensive clinical and cognitive assessments were carried out throughout the study and for an additional one month follow-up period. The results indicate that at the end of the treatment period, negative symptoms (as indicated by the Scale for the Assessment of Negative Symptoms (SANS)) significantly reduced in the TMS group (-7.7), but not in the sham group (-1.9). Differences between the groups were not statistically significant.

Topographic analysis of engagement and disengagement of neural oscillators in photic driving: a combined electroencephalogram/magnetoencephalogram study

OBJECTIVE

A coupled system of nonlinear neural oscillators with an individual resonance frequency is assumed to form the neuronal substrate for the photic driving phenomenon. The aim was to investigate the spatiotemporal stability of these oscillators and quantify the spatiotemporal process of engagement and disengagement of the neuronal oscillators in both multitrial and single-trial data.

METHODS

White light-emitting diode flicker stimulation was used at 15 frequencies, which were set relative to the individual α frequency of each of the 10 healthy participants. Simultaneously, the electroencephalogram (EEG) and the magnetoencephalogram (MEG) were recorded. Subsequently, spatiotemporal matching pursuit (MP) algorithms were used to analyze the EEG and MEG topographies.

RESULTS

Intraindividually similar topographies were found at stimulation frequencies close to (1) the individual α frequency and (2) half the individual α frequency in the multitrial and the single-trial cases. In both stimulation frequency ranges, the authors observed stable topographies 5 to 10 stimuli after the beginning of the stimulation and lasting three nonexisting periods after the end of the stimulation. This was interpreted as the engaging/disengaging effect of the observed oscillations, because especially the frequency parameter adopted before and after stable topographies were observed. Topographic entrainment was slightly more pronounced in MEG as compared with that in EEG.

CONCLUSIONS

The results support the hypothesis of nonlinear information processing in human visual system, which can be described by nonlinear neural oscillators.

Clozapine augments delta, theta, and right frontal EEG alpha power in schizophrenic patients

Objective. To explore the Quantitative EEG (QEEG) effects of established clozapine therapy regimes compared to those of previous ineffective antipsychotic regimes among 64 chronic (DSM-IV) schizophrenic patients. Methods. Data from 20 EEG channels referenced to linked ears were collected before and during maintenance clozapine therapy (mean duration 1.4 years). Absolute power was calculated in six frequency bands: delta (0.4–3.6 Hz), theta (4.2–7.8 Hz), alpha (8.2–11.8 Hz), beta1 (12.2–15.8 Hz), beta2 (16.2–19.8 Hz), and beta3 (20.2–23.8 Hz). Results. Clozapine augments power globally in the delta and theta bands, but this effect is more pronounced over frontal areas. Beta3 power was reduced. Alpha showed a frontal increase, more pronounced in the right, coupled with a posterior decrease with no net change in overall power. Conclusion. The demonstration of a significant clozapine-induced alpha topographic shift frontally and to the right is a novel discovery that may serve to encourage further investigations of subcortical structures in attempts to better understand the diverse aetiologies and optimal treatments of the schizophrenias.

Modeling brain resonance phenomena using a neural mass model

Stimulation with rhythmic light flicker (photic driving) plays an important role in the diagnosis of schizophrenia, mood disorder, migraine, and epilepsy. In particular, the adjustment of spontaneous brain rhythms to the stimulus frequency (entrainment) is used to assess the functional flexibility of the brain. We aim to gain deeper understanding of the mechanisms underlying this technique and to predict the effects of stimulus frequency and intensity. For this purpose, a modified Jansen and Rit neural mass model (NMM) of a cortical circuit is used. This mean field model has been designed to strike a balance between mathematical simplicity and biological plausibility. We reproduced the entrainment phenomenon observed in EEG during a photic driving experiment. More generally, we demonstrate that such a single area model can already yield very complex dynamics, including chaos, for biologically plausible parameter ranges. We chart the entire parameter space by means of characteristic Lyapunov spectra and Kaplan-Yorke dimension as well as time series and power spectra. Rhythmic and chaotic brain states were found virtually next to each other, such that small parameter changes can give rise to switching from one to another. Strikingly, this characteristic pattern of unpredictability generated by the model was matched to the experimental data with reasonable accuracy. These findings confirm that the NMM is a useful model of brain dynamics during photic driving. In this context, it can be used to study the mechanisms of, for example, perception and epileptic seizure generation. In particular, it enabled us to make predictions regarding the stimulus amplitude in further experiments for improving the entrainment effect.

Neuroscience aims to understand the enormously complex function of the normal and diseased brain. This, in turn, is the key to explaining human behavior and to developing novel diagnostic and therapeutic procedures. We develop and use models of mean activity in a single brain area, which provide a balance between tractability and plausibility. We use such a model to explain the resonance phenomenon in a photic driving experiment, which is routinely applied in the diagnosis of various diseases including epilepsy, migraine, schizophrenia and depression. Based on the model, we make predictions on the outcome of similar resonance experiments with periodic stimulation of the patients or participants. Our results are important for researchers and clinicians analyzing brain or behavioral data following periodic input.

Therapeutic effects of individualized alpha frequency transcranial magnetic stimulation (alphaTMS) on the negative symptoms of schizophrenia

Previous research in clinical electroencephalography (EEG) has demonstrated that reduction of alpha frequency (8-13 Hz) EEG activity may have particular relevance to the negative symptoms of schizophrenia. Repetitive Transcranial Magnetic Stimulation (rTMS) was utilized to investigate this relationship by assessing the therapeutic effects of stimulation set individually at each subject's peak alpha frequency (alphaTMS). Twenty-seven subjects, with predominantly negative symptom schizophrenia, received 2 weeks of daily treatment with either alphaTMS, 3 Hz, 20 Hz, or sham stimulation bilaterally over the dorsolateral prefrontal cortex. Individualized alphaTMS demonstrated a significantly larger (F (3,33) = 4.7, p = .007) therapeutic effect (29.6% reduction in negative symptoms) than the other 3 conditions (< 9%). Furthermore, these clinical improvements were found to be highly correlated (r = 0.86, p = .001) with increases (34%) in frontal alpha amplitude following alphaTMS. These results affirm that the resonant features of alpha frequency EEG play an important role in the pathophysiology of schizophrenia and merit further investigation as a particularly efficacious frequency for rTMS treatments.

Interaction between the flash evoked SSVEPs and the spontaneous EEG activity in children and adults

OBJECTIVE

To evaluate the interaction between the steady-state visual evoked potentials (SSVEPs) recorded during the intermittent photic stimulation (IPS) and the spontaneous EEG activities both in children and adults.

METHODS

EEG was recorded during the rest and under 5, 7.5, 10 and 12.5 Hz IPS in 41 children between 3 and 16 years and 10 adults. We distinguished between the spontaneous resting EEG spectra, SSVEPs (1st harmonic) and undriven (ongoing) EEG spectra recorded during the IPS.

RESULTS

We show that IPS influences spontaneous EEG activity by specifically suppressing or desynchronizing individual posterior dominant resting EEG frequencies (DF) in both children and adults. Further, this highly significant and consistent suppressing effect positively correlates with the SSVEPs amplitude.

CONCLUSIONS

Our data suggest that the desynchronization of the spontaneous EEG activity under IPS and the SSVEPs are related to each other.

SIGNIFICANCE

These relationships could be interesting to study in pathological conditions where the neural synchronization and the responses to IPS have been shown to be affected, such as epilepsy and schizophrenia.

Steady state visual evoked potential abnormalities in schizophrenia

OBJECTIVE

The steady state visual evoked potential (SSVEP) can be used to test the frequency response function of neural circuits. Previous studies have shown reduced SSVEPs to alpha and lower frequencies of stimulation in schizophrenia. We investigated SSVEPs in schizophrenia at frequencies spanning the theta (4Hz) to gamma (40Hz) range.

METHODS

The SSVEPs to seven different frequencies of stimulation (4, 8, 17, 20, 23, 30 and 40Hz) were obtained from 18 schizophrenia subjects and 33 healthy control subjects. Power at stimulating frequency (signal power) and power at frequencies above and below the stimulating frequency (noise power) were used to quantify the SSVEP responses.

RESULTS

Both groups showed an inverse relationship between power and frequency of stimulation. Schizophrenia subjects showed reduced signal power compared to healthy control subjects at higher frequencies (above 17Hz), but not at 4 and 8Hz at occipital region. Noise power was higher in schizophrenia subjects at frequencies between 4 and 20Hz over occipital region and at 4, 17 and 20Hz over frontal region.

CONCLUSIONS

SSVEP signal power at beta and gamma frequencies of stimulation were reduced in schizophrenia. Schizophrenia subjects showed higher levels of EEG noise during photic stimulation at beta and lower frequencies.

SIGNIFICANCE

Inability to generate or maintain oscillations in neural networks may contribute to deficits in visual processing in schizophrenia.

Electrical brain responses evoked by human faces in acute psychosis

Patients with schizophrenia are known to have behavioral deficits in recognizing faces and facial expressions. However, the ability to process simple visual stimuli appears to be intact in first-episode psychosis. The aim of this study was to examine complex visual processing, especially the event-related potentials (ERPs) elicited by human faces, in early psychosis. Never-medicated patients in acute psychosis (n=18) were compared with healthy controls (n=19). Photographs of human faces were presented in a classic oddball paradigm requiring a motor response to a smiling face. Cerebral sources of ERPs were analyzed of the averaged responses, using minimum norm estimates, and dipole models. Face-sensitive response at 145 ms after the face stimuli was of significantly higher amplitude in our never-medicated patients, and the activity distribution between the groups was clearly different. At the early phase of a psychotic illness, these alterations in face-related neuronal network processes represent perceptual disturbance in psychosis, possibly including state and trait, as well as potential physiological compensatory features.

A "new-old" way of thinking about brain disorder, cerebral excitability--the fundamental property of nervous tissue

Cerebral excitability is normally distributed, and pubertal age is a distinguishing factor. The final developmental event in CNS comprising selective pruning of excitatory synapses coincides with puberty. With early puberty, excess excitation and synaptic density, we have photic susceptibility, paroxysmal EEGs, disturbed circadian rhythms, paroxysmal disorders treated with drugs lowering excitation. Manic-depressive psychosis accords with this. Migraine with paroxysmal EEG, photophobia, hemianopsia, scintillating scotomas, excess excitation in the visual system, benefits from lowering excitation. With late puberty, attenuated CNS, we have disorders in need of raising excitation to avoid breakdown of circuitry, insufficient fill-in mechanism, silent spots, subjectively experienced only--objectively verifiable psychosis: i.e., schizophrenia treated with convulsant neuroleptics. By affecting pubertal age, we affect the distribution of excitation and of post-pubertal brain disorders in accordance with their level of excitation. Excitation is equally important in chronic disorders: l'dopa adversity in Parkinsonism could be due to further lowering of excitation in patients with a deficiency, a schizophrenia-like psychosis develops. Given unavoidable adversity of anti-psychotics, and a marked rise in suicide in schizophrenic and manic-depressive since their introduction, we want to prevent the occurrence of disorders at the extremes, whether very early or late puberty. DHA normalises excitability at all levels of excitation. An adequate daily intake of DHA, before puberty as well as after, might probably reduce or eliminate a development of psychopathology. Lithium is a robust neurotropic agent, and lithiation of the drinking water could be a way of reducing suicide, homicide, violent behaviour, and drug abuse.

Aberrant brain dynamics in schizophrenia: delayed buildup and prolonged decay of the visual steady-state response

In schizophrenia, aberrant brain activity has been reported both during stimulus processing and at rest. Evoked response amplitude is a function of both the number and synchronization of neurons firing in relation to a stimulus. It is at present unclear whether schizophrenia patients have normal synchronization of neural activity in relation to stimulus processing, and whether the amount and time course of synchronization is related to their evoked response amplitudes. EEG brain dynamics in response to visual steady-state stimulation were assessed in 12 schizophrenia and 12 healthy subjects at three stimulation durations (2, 4, and 6 s). Group differences in the visual evoked potential, the visual steady-state response, and the local coherence of the visual steady-state response were evaluated over time. Schizophrenia patients had smaller and delayed event-related potentials. Moreover, they had a slower buildup of steady-state amplitude following stimulation onset and a prolonged decrease after stimulation offset. Groups did not differ during mid-segments of steady-state stimulation. Increase in coherence to stimulation onset did not differ between-groups, but coherence decay of the visual steady-state response following stimulus offset was delayed in schizophrenia patients. The initial response to visual stimulation among schizophrenia subjects, therefore, may be reduced in amplitude due to weak signal strength, not poor coordination between distant cortical regions. The prolonged recovery function of schizophrenia patients' visual system may indicate abnormal nonlinearity in neural response. These findings have implications understanding the nature of evoked response differences between schizophrenia and normal groups especially in repetitive stimulus paradigms.

Hemispheric laterality and dimensional complexity in schizophrenia under sound and light stimulation

The aim of the present study is to investigate the relationship between linear and non-linear activities in human electroencephalograms (EEGs) by examining the linear lateral asymmetry index and the correlation dimension as a non-linear measure of complexity and to typify the characteristics of EEGs between schizophrenic patients and normal controls. We recorded the EEG from 16 electrodes in 10 schizophrenics (6 males and 4 females) and 10 age-matched normal controls (10 males), and calculated their asymmetry indices. The asymmetry index shows which hemispheric activity is dominant through examination of interhemispheric pairs in the frequency domain with EEGs between two regions. We also estimated correlation dimension. Remarkably, lower dimensional complexities appeared on the brain regions, which had significantly lower brain activity, as determined by a lateral asymmetry analysis, in schizophrenics before sound and light (SL) stimulation. We may suggest the possibility of co-varying of both linear and non-linear properties. This co-varying phenomenon maintained after the SL stimulation. Furthermore, schizophrenic patients revealed opposite asymmetric patterns compared to normal controls, as well as reversal phenomena and abnormalities in the left frontal region when SL stimuli were applied.

Quantitative EEG in schizophrenia and in response to acute and chronic clozapine treatment

Topographic quantitative electroencephalographic (EEG) power and frequency indices were collected in 17 treatment refractory, DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) clozapine treatment, as well as in 17 healthy volunteers. Prior to treatment, patients exhibited greater overall absolute theta power, slower mean alpha frequency and elevated absolute delta and total power in anterior regions. Acute dosing increased total spectrum power globally, slow wave power posteriorally, mean alpha frequency and beta power anteriorally and decreased alpha power posteriorally. Six weeks of clozapine treatment significantly reduced clinical ratings of positive and negative symptoms as well as symptoms of global psychopathology. Chronic treatment resulted in EEG slowing as shown by decreases in relative alpha power, mean beta/total spectrum frequency and by widespread increases in absolute total and delta/theta power. The preliminary findings suggest that brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions in schizophrenia.

Pharmacokinetic-pharmacodynamic modelling in the early development phase of anti-psychotics: a comparison of the effects of clozapine, S 16924 and S 18327 in the EEG model in rats

1. The use of pharmacokinetic/pharmacodynamic (PK/PD) analysis in early compound development was investigated in the rat for two developmental anti-psychotic compounds with clozapine as a positive control. 2. Three plasma samples were collected from each of eight animals according to a pre-defined sampling matrix allowing a total of 12 time points for PK analysis. Quantitative electroencephalography (QEEG), particularly the theta and beta frequencies, was used as a measurement of pharmacological effect. 3. PK/KD modelling of the sparse PK data available relative to a rich set of PD data was achieved using a population approach in NONMEM (IV). Individual PK parameter estimates were incorporated into a PK/PD model. 4. Qualitative EEG changes in rat and human were similar for clozapine, but different for the two developmental compounds, suggesting that changes in these PD parameters may not be specifically related to the anti-psychotic activity. 5. Although no definitive data are available concerning the signal specificity of EEG frequency bands with respect to dopaminergic or serotonergic receptor activity, qualitative and quantitative differences seen in EEG parameters are likely to result from the multiple receptor occupancy for these compounds. 6. The results confirm the value of population PK/PD modelling in conjunction with sparse sampling to enable determination of concentration effect relationships in the pre-clinical development programme of CNS-active drugs.

EEG resonant responses in schizophrenia: a photic driving study with improved harmonic resolution

Twenty seven drug-free schizophrenic patients and 25 normal controls were studied in an EEG photic driving paradigm with an improved harmonic resolution. Consistent with previous results, the present data show that schizophrenics have lower EEG responses to photic stimulation in alpha frequency. The differences between normal and schizophrenic subjects were distributed across major brain areas except centro-temporal regions. It also demonstrated that 1-Hz narrow-pulsed stimulation was feasible in EEG photic driving studies. The enhanced harmonic resolution produced significantly more information in the frequency domain about EEG oscillatory responses to visual stimulus. Using this new technique, the authors showed for the first time that alpha photic driving was a well defined resonant system and that the group differences in harmonic responses were primarily confined in the high frequency portion of alpha band, suggesting a peak frequency shift of EEG resonance in schizophrenia.

Clozapine versus typical neuroleptic medication for schizophrenia

BACKGROUND

Long-term drug treatment of schizophrenia with conventional antipsychotics has limitations: 25-33% of patients have illnesses that are treatment-resistant. Clozapine is an atypical antipsychotic drug, which is claimed to have superior efficacy and to cause fewer motor adverse effects than typical drugs for people with treatment-resistant illnesses. Clozapine carries a significant risk of serious blood disorders, which necessitates mandatory weekly blood monitoring at least during the first months of treatment.

OBJECTIVES

To evaluate the effects of clozapine for schizophrenia in comparison to typical antipsychotic drugs.

SEARCH STRATEGY

Publications in all languages were searched from the following databases: Biological Abstracts (1982-1999), The Cochrane Library CENTRAL (Issue 2, 1999), Cochrane Schizophrenia Group's Specialised Register (1999), EMbase (1980-1999), ISI Citation Index, LILACS (1982-1999), MEDLINE (1966-1999), and PsycLIT (1974-1999). Reference list screening of included papers was performed. Authors of recent trials and the manufacturer of clozapine contacted.

SELECTION CRITERIA

All randomised controlled trials comparing clozapine with typical antipsychotic drugs were included by independent assessment by at least two reviewers.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by at least two reviewers. Authors of trials published since 1980 were contacted for additional and missing data. Odds ratios (OR) and 95% confidence intervals (CI) of homogeneous dichotomous data were calculated with the Peto method. A random effects model was used for heterogeneous dichotomous data. Where possible the numbers needed to treat (NNT) or needed to harm (NNH) were also calculated. Weighted or standardised means were calculated for continuous data.

MAIN RESULTS

Currently the review includes 31 studies, 26 of which are less than 13 weeks in duration. These studies include 2589 participants, most of whom were men (74%). The average age was 38 years. There was no difference in the effects of clozapine and typical neuroleptic drugs for broad outcomes such as mortality, ability to work or suitability for discharge at end of the study. Clinical improvement was seen more frequently in those taking clozapine (random effects OR 0.4 CI 0.2-0.6, NNT 6) both in the short and the long term. Also, in the short term, participants on clozapine had fewer relapses than those on typical antipsychotic drugs (OR 0.6 CI 0.4-0.8, NNT 20 CI 17-38), and this may be true for long-term treatment as well. Symptom assessment scales showed a greater reduction of symptoms in clozapine-treated patients. Clozapine treatment was more acceptable than low-potency antipsychotics such as chlorpromazine (OR 0.6 CI 0.4-0.9) but did not differ from acceptability of high-potency neuroleptics such as haloperidol (random effects OR 0.8 CI 0.4-1.5). Clozapine was more acceptable in long-term treatment than conventional antipsychotic drugs (random effects OR 0.4 CI 0.2-0.7, NNT 6 CI 3-111). Patients were more satisfied with clozapine treatment (OR 0.5 CI 0.3-0.8, NNT 12 CI 7-37), but they experienced more hypersalivation, temperature increase, and drowsiness than those given conventional neuroleptics. However, clozapine patients experience fewer motor side effects and less dry mouth. The clinical efficacy of clozapine was more pronounced in participants resistant to typical neuroleptics in terms of clinical improvement (random effects OR 0.2 CI 0.1-0.5, NNT 5 CI 4-7) and symptom reduction. Thirty-two percent of treatment resistant people had a clinical improvement with clozapine treatment.

REVIEWER'S CONCLUSIONS

This systematic review confirms that clozapine is convincingly more effective than typical antipsychotic drugs in reducing symptoms of schizophrenia, producing clinically meaningful improvements and postponing relapse. Patients were more satisfied with clozapine treatment than with typical neuroleptic treatment. (ABSTRACT TRUNCATED