Peter Falkai

Evidence for activation of microglia in patients with psychiatric illnesses

Activation of microglia/macrophages is a key event in response to pathological changes in the CNS. HLA-DR is a valuable immunohistochemical marker that specifically reacts with activated microglia cells. In order to elucidate a potential role of microgliosis in severe psychiatric illnesses, post-mortem frontal cortex and hippocampus of patients with schizophrenia (n = 14) and affective disorder (n = 6) and control specimens (n = 13) were studied. Additionally Alzheimers disease cases (n = 8) were included as a human model system with typical neurodegenerative alterations and microglia activation. All patient groups revealed subjects with abundant microglia immunostaining (schizophrenia, three patients; affective disorder, one patient; Alzheimers disease, four patients) in both gray and white matter. This finding provides evidence for distinct neuropathological changes in brains of patients with schizophrenia and affective disorder. The activation of microglia cells, which represent a major part of the brain immune response, may help to unravel the pathophysiological processes in severe psychiatric illnesses.

Vagus nerve stimulation is associated with mood improvements in epilepsy patients

Vagus nerve stimulation (VNS) has gained increasing acceptance for treatment of drug-resistant seizures. The aim of this study was to evaluate effects of VNS on depressed mood in epilepsy patients during the first 6 months after implantation of the stimulation device. This study was conducted as an addition to the international multisite randomized and double-blind controlled trial on anti-seizure effects of VNS (EO3). Only adult patients with >4/month medication-resistant complex-partial seizures were included (N=11). During the acute phase of the study (3 months after implantation), patients were randomly assigned to low (stimulation detection) versus high stimulation (maximal tolerability, maximum 1.75 mA). Mood and mood changes were recorded based on standardized psychiatric rating scales and self-report questionnaires. Patients were assessed 4 weeks before (baseline) as well as 3 and 6 months after implantation. Significant positive mood effects were observed in most scales and subscales at the 3-month follow-up (P<0.05). Mood improvements were sustained at the 6-month follow-up and were independent of effects on seizure activity (9/11 mood responders versus 2/11 seizure responders). Mood effects appeared more pronounced in the high stimulation group after the acute study phase, but findings were not significant (P<0.10). VNS is associated with mood improvements in patients with epilepsy, but to confirm VNS dose effects, studies with more statistical power are needed.

Genetic and non-genetic vulnerability factors in schizophrenia: the basis of the "two hit hypothesis".

Schizophrenia is a psychiatric disorder that aCicts 0.5‐1% of the general population. It is clinically characterized by disturbed thought processes, delusions, hallucinations and/or reduced social skills (Andreasen, 1995). This severe mental disorder strikes human beings in their early adulthood, causes lifelong disability for most of the suAerers and is therefore one of the ten most expensive disorders worldwide. Its direct and indirect costs mount up to 33 billion dollars per year, while aCicting all ethic backgrounds, genders, socioeconomic classes and nationalities. The course of the illness is characterized by episodes of acute psychotic symptoms followed by phases of remission where symptoms like reduced drive and aAect as well as disturbed cognitive functions prevail. Despite the severeness of the disorder its origins are unclear until now. The neuropathological and neuroanatomical findings in patients with schizophrenia have been proposed to arise from dysfunction of structural reorganization during early brain development (Waddington, 1993; Weinberger, 1995), or postnatally from altered maturation of synaptic elimination (Feinberg, 1982). Morphometric and in vivo neuroimaging studies described enlarged ventricles, cerebral atrophy of temporal lobe and prefrontal structures, and increase in the gyrification index (Arnold and Trojanowski, 1996). One of the most consistent results is the lack of astrogliosis in schizophrenic brains, which would be a requirement for severe and chronic neurodegenerative

Schizophrenia and anteroventral thalamic nucleus: selective decrease of parvalbumin-immunoreactive thalamocortical projection neurons

This study was designed to examine possible anatomical changes of thalamocortical circuits in schizophrenics. Previous immunocytochemical studies have shown that parvalbumin, a calcium-binding protein, occurs in thalamocortical projection neurons, but not in GABAergic interneurons in the anteroventral thalamic nucleus (AN). Using parvalbumin-immunocytochemistry we investigated the densities of thalamocortical projection neurons in the AN of schizophrenic cases (n = 12) and controls (n = 14). The densities of all neurons in the AN were estimated by Nissl-staining. The majority of thalamocortical projection neurons in AN were identified by parvalbumin-immunoreaction. Significantly reduced densities of thalamocortical projection neurons were estimated in the right (P = 0.003) and left AN (P = 0.018) in schizophrenic subjects. The densities of all neurons in right and left AN were also diminished in schizophrenics; however, these decreases did not reach statistical significance. The reductions of parvalbumin-positive thalamocortical projection neurons were not correlated with the length of disease, this finding supporting the neurodevelopmental etiology of structural abnormalities in schizophrenia.

No evidence for astrogliosis in brains of schizophrenic patients. A post-mortem study

Schizophrenia is clinically and neuropsychologically characterized by severe cognitive and functional impairment suggesting the presence of a neurodegenerative process in the brains of affected individuals. A variety of neuroanatomical changes have been described such as loss and disorientation of neurons in grey and white matter and cortical atrophy. However, the neuropathological basis for schizophrenia is still unclear. In the present study we monitored the density of GFAP‐positive astrocytes in brains of 33 schizophrenic patients and 26 healthy controls. Both grey matter (entorhinal cortex and subiculum) and white matter (premotor cortex, subventricular zone of the third ventricle and next to inferior horn) structures were measured bilaterally. The overall finding was that there is no evidence for increased astrogliosis in brains of schizophrenic patients vs healthy controls. Therefore, degeneration is unlikely to be the main neuropathological mechanism in schizophrenic brains.

Volumes of association thalamic nuclei in schizophrenia: a postmortem study

The major association thalamic nuclei, the mediodorsal nucleus (MD) and the medial pulvinar nucleus (PUM) are regarded as important parts of the circuits among association cortical regions. Association cortical regions of the frontal, parietal and temporal lobes have been repeatedly implicated in the neuropathology of schizophrenia. Thus, the aim of the present postmortem study was to investigate the volumes of association thalamic nuclei in this disease. The volumes of the whole thalamus (THAL), MD and PUM were measured in each hemisphere of brains of 12 patients with schizophrenia and 13 age-matched and gender-matched normal control subjects without neuropsychiatric disorders. Patients with schizophrenia exhibited significant volume reductions in both the MD and the PUM, the reductions being more pronounced in the PUM. The volume of the PUM in the left (-19.7%, P=0.02) and right (-22.1%, P=0.01) hemispheres was significantly reduced in the schizophrenia group. The volume of the MD was reduced in both hemispheres in the schizophrenia group. However, the volume reduction was only significant in the left hemisphere (-9.3%, P=0.03). Patients with schizophrenia also exhibited a decreased volume of the THAL in the left (-16.4%, P=0.003) and right (-15.2%, P=0.006) hemispheres. There were no significant correlations between thalamic volumes and duration of illness or age of the patients. In conclusion, the present data indicate volume reductions of association thalamic nuclei in schizophrenia. These anatomical findings are consistent with the view that schizophrenia may be associated with disturbances of association cortical networks. However, the findings of a substantial volume reduction of the THAL suggest that the volumes of additional thalamic nuclei may be also reduced in schizophrenia.

Entorhinal cortex pre-alpha cell clusters in schizophrenia: quantitative evidence of a developmental abnormality

BACKGROUNDnPrevious studies using semiquantitative or qualitative techniques demonstrated abnormalities of positioning of clusters of neurons (pre-alpha cells) in the entorhinal cortex in schizophrenia, suggesting a developmental mechanism could contribute to the illness. Recent quantitative studies of laminar thickness and laminar cell counts have been less consistent, and several failed to replicate the finding. However, none of the quantitative studies focused on the position of the pre-alpha cell clusters.nnnMETHODSnTo study pre-alpha cell position in detail, we examined the entorhinal cortex in serial sections from 21 control and 19 schizophrenic brains. Cluster position relative to the gray-white matter junction and cluster size were measured.nnnRESULTSnQuantitative assessment of 1991 clusters indicated clusters were positioned relatively closer to the gray-white matter junction in the anterior half of schizophrenic entorhinal cortices. In addition, the size of clusters in males with schizophrenia was reduced.nnnCONCLUSIONSnThese results support the model of schizophrenia as an illness in which brain development is impaired. The findings in males with schizophrenia may indicate the presence of more severe pathology, or an additional pathogenic mechanism.

Amplitude reduction of the mismatch negativity in first-degree relatives of patients with schizophrenia.

First-degree relatives of schizophrenic patients display alterations in various cognitive domains and their electrophysiological counterparts similar to schizophrenic subjects. The mismatch negativity (MMN) is an event-related potential that reflects sensory memory in the pre-attentive stage of auditory processing. An amplitude reduction of the MMN has been reported in schizophrenia. The present study investigated the MMN in patients with schizophrenia, first-degree relatives and control subjects. The MMN amplitude was reduced in relatives compared to controls. The MMN amplitude reduction in schizophrenic patients compared to controls, however, did not reach significance in the present study. These results provide first evidence for disturbed sensory memory in relatives of patients with schizophrenia.

α-Synuclein accumulates in Lewy bodies in Parkinson's disease and dementia with Lewy bodies but not in Alzheimer's disease β-amyloid plaque cores

A growing body of evidence suggests that the non-Aβ component of Alzheimers disease amyloid precursor protein (NACP) or α-synuclein contributes to the neurodegenerative processes in Alzheimers disease (AD), Parkinsons disease (PD) and dementia with Lewy bodies (DLB). In the present study antisera to the N terminus and the NAC domain of the α-synuclein protein were employed to elucidate the expression pattern in brains of patients with AD, PD, DLB and control specimen. α-Synuclein exhibited an overall punctuate expression profile compatible with a synaptic function. Interestingly, while Lewy bodies were strongly immunoreactive, none of the α-synuclein antisera revealed staining in mature β-amyloid plaques in AD. These observations suggest that α-synuclein does not contribute to late neurodegenerative processes in AD brains.

Antidepressive treatment in patients with temporal lobe epilepsy and major depression: a prospective study with three different antidepressants

Major depression (MD) is underdiagnosed and undertreated in patients with temporal lobe epilepsy (TLE). Side effects of some antidepressants, like increased risk of seizures and drug-drug interactions with anticonvulsants, contribute to undertreatment of MD in patients with TLE. We analyzed post hoc the data from 2 years of treatment of inpatients with MD and TLE. Seventy-five patients received standard treatment with citalopram, mirtazapine, or reboxetine, respectively, at recommended dosage. Examinations were done with the Hamilton Rating Scale for Depression at admission and after 4 and 20-30 weeks. Plasma levels of anticonvulsants were examined at admission and discharge. Seizures were documented. The antidepressive treatment was efficacious in all antidepressant groups. No case of serious adverse event or drug interaction occurred. There was no increase in frequency or severity of seizures. At endpoint the dropout rate for mirtazapine was significantly higher than that for reboxetine or citalopram. Reboxetine showed a trend to be more efficacious than citalopram but not mirtazapine at Week 4.