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Andreas J Fallgatter

Publications and source records attributed to Andreas J Fallgatter.

At least 19 recordsLinked to original sources
PubMed2026

Effects of quetiapine on cognitive functioning in schizophrenia: evidence for the remyelination hypothesis?

Postmortem findings, neuroimaging data, and in-vitro models suggest a decrease in number and density of oligodendrocytes is driving cognitive deficits in schizophrenia (SCZ). Second-generation antipsychotics are discussed to improve oligodendrocyte dysfunction with most conclusive evidence available for quetiapine (QET). We postulate that sustained QET treatment leads to cognitive improvement in SCZ, particularly, in tests with high demands for working memory function. We further hypothesize that these effects are moderated by polygenic factors associated with hippocampus-related brain volumes, general white matter integrity, and/or oligodendroglia-related SCZ risk. Using data of the prospective PsyCourse study, we identified 166 patients with SCZ spectrum disorder receiving QET at one or two consecutive visits plus 166 matched patients without QET. Polygenic scores were calculated for subcortical brain volumes, measures of white matter integrity, and for cell type-specific genetic SCZ risks. QET treatment was consistently associated with improved cognitive function independent of time, specifically, in tests with high, but not with low to medium working memory load. Polygenic analyses did not reveal significant moderation effects. In contrary, low genetic SCZ risk specific for genes related to human oligodendrocyte function was associated with higher cognitive performance independent from QET. While we observed improved cognitive performance under QET in high working memory tests, we did not find evidence that polygenic factors associated with hippocampus-related brain volumes, white matter integrity, or oligodendroglia-related SCZ risk moderate this association. Thus, our tentative findings do not provide evidence for the hypothesis that polygenic estimates of hippocampal remyelination capacities influence the association between QET and cognitive performance in SCZ.

Humans↗
PubMed2007

Improvement of prefrontal brain function in endogenous psychoses under atypical antipsychotic treatment.

Typical and atypical antipsychotics are thought to exert their effects on different neurotransmitter pathways with specific action of atypical compounds on the prefrontal cortex, but studies directly investigating the effect of those drugs on neurophysiological measures of prefrontal brain function are sparse. We therefore investigated the influence of different antipsychotics on an electrophysiological marker of prefrontal brain function (NoGo anteriorization, NGA) and neuropsychological test scores. For this purpose, 38 patients with endogenous psychoses were investigated at the beginning of a stationary psychiatric treatment and at a 6-week-follow-up. Patients were treated with typical or atypical antipsychotics, or a combination of both. They underwent psychopathological diagnostic and neuropsychological testing, as well as electrophysiological investigations during a Continuous Performance Test. The results indicate that typical and atypical antipsychotics differentially affected the development of the NGA over the course of the treatment, typical antipsychotics tending to result in decreased values at follow-up, and atypical antipsychotics stabilizing, or increasing this parameter. Performance in tests of frontal lobe function generally declined under typical antipsychotics and improved with atypical compounds, changes in Stroop interference correlated with changes in the NGA. We conclude that typical and atypical antipsychotics differ regarding their effect on prefrontal brain function in schizophrenia, atypical neuroleptics often showing a more favorable impact than conventional antipsychotics on respective parameters.

Adult↗
PubMed2006

Impact of catechol-O-methyltransferase on prefrontal brain functioning in schizophrenia spectrum disorders.

The enzyme catechol-O-methyltransferase (COMT) has attracted increasing interest regarding a genetic disposition towards schizophrenias and as a modulator of prefrontal brain function. A common SNP in the COMT gene causes a Val to Met transition at AA158/AA108 (Val158Met), resulting in reduced COMT activity in Met allele carriers. An impact of COMT genotype on cognition has been well established; however, the exact nature of this influence has yet to be elucidated. The aim of this study was to determine whether COMT genotype affects an electrophysiological marker of prefrontal activation and neuropsychological frontal lobe measures in schizophrenia. To this end, 56 acutely psychotic in-patients with schizophrenia spectrum disorders were investigated. Patients with the COMT 1947AA (Met/Met) genotype (n=13) were compared to a carefully matched sample of patients with a G1947A (Val/Met) genotype (n=15); matching criteria included patients' age, handedness, gender distribution, diagnosis, and medication status. A small group of six homozygous Val allele carriers was additionally included to allow an assessment of possible gene-dosage effects. P300 amplitudes and latencies, as well as an electrophysiological marker of prefrontal brain function (NoGo-Anteriorization/NGA) and neuropsychological measures (Stroop Test, Verbal Fluency, Trail Making Test) were regarded. Homozygous Met allele carriers had significantly increased NGA values and fronto-central Nogo amplitudes compared to patients with at least one Val allele. They also tended to perform better in the Stroop task, as compared to the matched group of Val/Met patients. These results indicate that COMT genotype exerts a strong impact on prefrontal functioning and executive control in schizophrenia spectrum disorders.

Adolescent↗
PubMed2006

Additive effects of serotonin transporter and tryptophan hydroxylase-2 gene variation on emotional processing.

Prior studies reported that functional variants of both the serotonin transporter (5-HTT) and tryptophan hydroxylase-2 genes (TPH2), 2 key regulators of the serotonergic signaling pathway, modulate amygdala activation during emotional processing. We addressed the question whether these 2 gene variants modulate each other, using an emotional picture-processing task. Specifically, we measured event-related potentials (ERPs) during a passive emotional picture perception task, focusing on ERPs for the early posterior negativity (EPN) around 240 ms and for the slow wave starting at 315 ms. We found evidence for increased neural activity at 240 ms in individuals who carried 1 or 2 copies of the low-expression short variant of the 5-HTT. Carriers of T variant of the TPH2 also showed a tendency toward increased neural activity at 240 ms. Moreover, we observed an additive effect of both genotypes for EPN, with highest neural activity to emotional stimuli in individuals carrying combination of both short variant of 5-HTT and T variant of TPH2. Our results indicate that both the 5-HTT and the TPH2 genotypes modulate the sensory encoding of affective stimuli during early steps of visual processing and reveal additive effects of 2 genes in the serotonergic control of emotion regulation.

Adult↗
PubMed2006

Facial affect decoding in schizophrenic disorders: a study using event-related potentials.

Deficits in emotional processing are evident in schizophrenia, but the underlying processes are still under debate. In this study we tried to replicate findings of diminished prefrontal electroencephalographic response during facial affect recognition in healthy controls and subsequently in schizophrenic patients. As a first step, we analysed the event-related potentials (ERPs) of 36 healthy subjects during emotional expression decoding compared with neutral face viewing. Subsequently, the ERPs of 22 patients with schizophrenia were compared with the ERPs of 22 healthy subjects matched for age and sex. The hypothesised increase in the negative component at 200 ms over frontal brain regions during facial affect decoding was not found in this study. Instead we found increased positive amplitudes at 300 ms over parietal brain areas for the active affect-decoding task compared with the passive neutral face-viewing task. Interestingly, schizophrenic patients had higher amplitudes in the neutral condition than did healthy controls. This effect was more pronounced in the paranoid subgroup of patients.

Adult↗
PubMed2006

DTNBP1 (dysbindin) gene variants modulate prefrontal brain function in healthy individuals.

DTNBP1 (dysbindin) is one of the several putative schizophrenia genes supported by association, neuroanatomical, and cellular studies. These suggest an involvement of DTNBP1 in the prefrontal cortex and cognitive functions mediated by interaction with neurotransmitter systems, in particular glutamate. The influence of DTNBP1 gene variation on prefrontal brain function at the systemic neurophysiological level, though, has not been characterized. The NoGo-anteriorization (NGA) as an event-related potential (ERP) measure elicited during the continuous performance test (CPT) has been established as a valid neurophysiological parameter for prefrontal brain function in healthy individuals and patients with schizophrenias. In the present study, we therefore investigated the influence of eight dysbindin gene variants on the NGA as a marker of prefrontal brain function in 48 healthy individuals. Two DTNBP1 polymorphisms previously linked to schizophrenia (P1765 and P1320) were found associated with changes in the NGA. Post hoc analysis showing an influence of genetic variation at these loci on the Go centroid and frontal amplitudes suggest that this might be due to modification of the execution of motor processes by the prefrontal cortex. This is the first report on a role of DTNBP1 gene variation for prefrontal brain function at a systemic neurophysiological level in healthy humans. Future studies will have to address the relevance of this observation for patients with schizophrenias.

Adult↗
PubMed2005

Source localization of early stages of face processing.

Recent studies using ERPs in face recognition revealed that face processing starts around 100 ms after stimulus onset, 70 ms earlier than suggested before. While the neural sources of the N 170 component have repeatedly been found to be localized in the gyrus fusiformis and the inferior occipital cortex, sources have not yet been investigated for the P100 component during face processing. Therefore, we measured the ERPs elicited by faces and control stimuli in 72 subjects in order to localize the neural sources of both the P100 and the N 170 component. We observed significantly higher P100 and N 170 amplitudes to faces compared to control stimuli. LORETA source localization revealed significantly higher brain activity in the left and right gyrus fusiformis for the N 170 component, with additional regions of increased brain activation in a parieto-temporal-occipital network. For the P100, faces activated the left and right gyrus fusiformis significantly stronger than control stimuli. This study reveals that the first step of face processing (about 100 ms after stimulus presentation) is localized in the gyrus fusiformis. The second step of face processing around 170 ms involves the gyrus fusiformis, with additional activation in a more distributed network, including the occipital cortex.

Adolescent↗
PubMed2005

Unconscious manipulation of free choice in humans.

Previous research has shown that subliminally presented stimuli accelerate or delay responses afforded by supraliminally presented stimuli. Our experiments extend these findings by showing that unconscious stimuli even affect free choices between responses. Thus, actions that are phenomenally experienced as freely chosen are influenced without the actor becoming aware of the manipulation. However, the unconscious influence is limited to a response bias, as participants chose the primed response only in up to 60% of the trials. LRP data in free choice trials indicate that the prime was not ineffective in trials in which participants chose the non-primed response as then it delayed performance of the incongruently primed response.

Adult↗
PubMed2005

Carbohydrate-deficient transferrin parallels disease severity in anorexia nervosa.

Carbohydrate-deficient transferrin (CDT) is a commonly used biomarker for alcohol abuse; however, recent findings questioned its diagnostic value in catabolic subjects. We have thus investigated possible changes of CDT in patients suffering from eating disorders. Retrospectively, CDT values of patients with eating disorders were identified. Twenty-four non-alcoholic subjects could be found, in which CDT was determined at least once during stationary psychotherapy. Anorexia nervosa patients had pathological CDT concentrations in 57% of cases; conversely, bulimia nervosa patients had normal CDT. Patients with initially elevated CDT tended to be more seriously ill than those without. During therapy, the body mass index of anorexia nervosa patients normalized, paralleled by declining CDT. In anorexia nervosa patients, CDT is unsuitable as a marker of alcohol abuse, but it might serve as a parameter indicating prognosis and disease severity. However, case-control studies with larger samples are warranted.

Adult↗
PubMed2005

Diminished prefrontal brain function in adults with psychopathology in childhood related to attention deficit hyperactivity disorder.

The aim of the present study was to investigate prefrontal brain function and cognitive response control in patients with personality disorders who either suffered or did not suffer from psychopathology related to attention deficit hyperactivity disorder (ADHD) during childhood. For this purpose, 36 psychiatric out-patients with personality disorders--24 of whom showed ADHD-related psychopathology during childhood assessed by the German short form of the Wender Utah Rating Scale--and 24 healthy controls were investigated electrophysiologically by means of a cued Go-NoGo task (Continuous Performance Test). Topographical analyses were conducted to individually quantify the NoGo anteriorisation (NGA), a neurophysiological correlate of prefrontal response control that has been suggested to reflect activation of the anterior cingulate cortex. ADHD patients exhibited a significantly reduced mean NGA and diminished amplitudes of the Global Field Power, as well as a reduced increase of fronto-central P300 amplitudes, in NoGo-trials compared with the healthy controls, whereas patients with personality disorders alone did not differ from the control group in any of the electrophysiological parameters. The results indicate that ADHD-related psychopathology is associated with prefrontal brain dysfunction, probably related to processes of response inhibition and/or cognitive response control.

Adult↗
PubMed2005

Optical topography during a Go-NoGo task assessed with multi-channel near-infrared spectroscopy.

In this study we investigated the functional brain activation during response inhibition by means of concentration changes in oxygenated [O2Hb] and deoxygenated [HHb] hemoglobin. 9 subjects were measured with multi-channel near-infrared spectroscopy (NIRS) over the left and right lateral prefrontal cortex. The activation task consisted of three blocks of cued Go-NoGo conditions, which were contrasted with three blocks of cued Go conditions. The Go- and Go-NoGo blocks lasted 30 s each, were presented in alternating order, and were preceded by a 30 s resting period. The results clearly show that both conditions induced a brain activation consisting of significant increases of [O2Hb] and decreases of [HHb]. These effects indicate that an active control condition is necessary for the adequate interpretation of the results. Most importantly, we found significantly higher increases of [O2Hb] and decreases of [HHb] during the inhibition phase as compared to the simple motor response in bilateral inferior frontal regions of the brain, which is in accordance with other brain imaging studies. With the introduction of an active control condition in this study, we improved the methodology of a previous investigation. We conclude that multi-channel NIRS is suitable for the functional identification of the inferior prefrontal brain area activated during response inhibition.

Adult↗
PubMed2005

Beneficial effect of atypical antipsychotics on prefrontal brain function in acute psychotic disorders.

Disturbance of prefrontal brain functions is assumed to be responsible for prominent psychopathological symptoms in psychotic disorders. Treatment with atypical, in contrast to typical antipsychotics is considered as a possible strategy for an improvement of prefrontal brain function. In the present study, response control as a specific prefrontal brain function was assessed by means of the Nogo-anteriorization (NGA) derived from the event-related potentials elicited during a Go-NoGo task in a consecutive sample of 39 patients suffering from acute psychotic disorders (brief psychotic disorders, 298.8, n = 34 and schizoaffective disorders, 295.70, n = 5; cycloid psychoses according to the Leonhard classification). A highly significant positive correlation between the amount of antipsychotic medication in terms of chlorpromazine equivalents per day and the NGA as a measure of prefrontal response control was only found in the subgroup of patients treated exclusively or predominantly with atypical antipsychotics but not for those treated with typical antipsychotics. These results are in line with the notion that atypical antipsychotics may exert a beneficial effect on prefrontal brain function.

Adult↗
PubMed2005

Evidence for unaltered brain electrical topography during prefrontal response control in cycloid psychoses.

OBJECTIVE: Prefrontal structures such as the anterior cingulate cortex (ACC) play a decisive role in processes of action monitoring and response control, functions often impaired in schizophrenia. Patients with cycloid psychoses exhibit some characteristic neurophysiological features not indicative of the cerebral hypofrontality observed in schizophrenia. This study aimed at examining if cycloid psychoses-unlike schizophrenias-involve a normal brain-electrical topography during a task demanding prefrontal response control. METHODS: Thirty-seven patients with cycloid psychoses and 37 healthy controls were investigated electrophysiologically while performing a Continuous Performance Test (CPT). Topographical analyses were conducted to individually quantify the Nogo-anteriorisation (NGA) as a neurophysiological index of prefrontal response control. RESULTS: The patients exhibited an unaltered topography with a mean NGA not significantly different from the controls. They did, however, differ from the control group regarding their Global Field Power (GFP), with a significantly reduced GFP (p<0.001) and decreased latencies (p<0.01) during Nogo trials. On a behavioral level, patients exhibited prolonged reaction times and an increased rate of omission errors. CONCLUSIONS: The investigated patients showed an activation of specific (presumably frontal) brain areas during Nogo trials, resulting in a frontalisation of the brain-electrical field comparable to the control group. However, the strength of this activation was apparently reduced. The patients' unaltered topographical pattern contrasts with previous findings in schizophrenic patients and supports the hypothesis that cycloid psychoses entail less severe prefrontal deficits than schizophrenias, which might be an indication of different biological backgrounds for both groups of endogenous psychoses.

Adult↗
PubMed2004

Altered functioning of the cingulate gyrus in two cases of chromosome 22q11 deletion syndrome.

The 22q11 microdeletion syndrome (22q11-DS) is strongly associated with schizophreniform disorders and, in turn, the 22q11 deletion region harbours several candidate genes for schizophrenia. Here, we present the case of an adolescent female patient with 22q11-DS associated with impaired cognitive abilities and behavioural abnormalities. The patient was studied with magnetic resonance imaging (MRI) and positron emission tomography (PET) as well as extensive neurophysiological investigations. Although no structural or functional abnormalities were found in MRI and PET, assessment of event-related potentials elicited during the Continuous Performance Test revealed a lack of NoGo anteriorisation. The latter was replicated in a second case of 22q11-DS with schizoaffective disorder but devoid of a severe somatic syndrome. This electrophysiological finding, which indicates modified functioning of the cingulate gyrus, has previously been demonstrated only in patients suffering from schizophrenia and attention deficit/hyperactivity disorder, two psychopathological conditions frequently associated with 22q11-DS. We conclude that more extensive study of NoGo anteriorisation as a potential endophenotype of 22q11-DS patients at risk for 22q11-associated psychiatric conditions is warranted.

Adolescent↗
PubMed2004

Age effect on far field potentials from the brain stem after transcutaneous vagus nerve stimulation.

Recently, a new electrophysiological method for the assessment of vagus nerve function in the brainstem has been proposed in healthy participants. Before this procedure may be applied to patients with neurodegenerative diseases, its feasibility in elderly healthy participants and a possible age effect on the measurement have to be investigated. The vagus sensory evoked potentials (VSEP) after transcutaneous electric stimulation of the sensory auricular branch of the vagus nerve have been assessed in healthy younger and elderly participants. VSEP measured as far field potentials probably originating in vagus nuclei in the brainstem were recorded in 20 of 22 younger as well as in 39 of 43 elderly healthy participants. Latencies were significantly longer in the elderly as compared to the younger participants, while no clear age effects on amplitudes were identified. These results indicate that the assessment of VSEP is feasible also in elderly healthy participants. This is a prerequisite for testing this method in elderly patients with neurodegenerative diseases like Alzheimer and Parkinson disease as a noninvasive tool to detect an affection of the brainstem nuclei of the vagus nerve early in their course.

Adult↗
PubMed2004

Sensory gating deficit in a subtype of chronic schizophrenic patients.

The dual click P50 paradigm has been established as a neurophysiological method to detect gating mechanisms. Studies of schizophrenic patients have shown that an insufficient reduction of the P50 amplitude after the second relative to the first stimulus indicates a deficient sensory gating mechanism. The aim of this study was to compare the P50 responses in the dual click paradigm of healthy volunteers to those of patients with different psychotic disorders, especially with regard to psychopathology and nosology according to ICD-10 and DSM-IV and to the classification system of Leonhard. A total of 34 patients and 12 healthy volunteers were investigated electrophysiologically while they performed the P50 dual click experiment. Patients with prominent negative symptoms and without perceptual abnormalities and patients with a hebephrenic subtype of schizophrenia showed less suppression in the dual click P50 paradigm than did healthy controls. Patients with brief/acute and transient psychotic disorders or cycloid psychoses did not differ from healthy volunteers with regard to suppression in the dual click P50 paradigm. No striking influence of gender, age, duration of disease and present medication was found. The findings confirm the lack of sensory gating measured by the dual click P50 paradigms in some but not all patients with schizophrenia. Both subtype of schizophrenia and current form of psychopathology appear to be related to the presence or absence of abnormal sensory gating.

Adult↗