Visuo-spatial navigation performance and parietal cortex volumes in schizophrenic patients using the "virtual-reality" paradigma

Erst wenige Arbeiten haben sich mit parietalen Dysfunktionen im Rahmen der Schizophrenie beschäftigt. Daher zielt die vorliegende Studie darauf ab, Defizite in klassischen "parietalen" Hirnfunktionen mit Hilfe einer virtuellen Navigationsaufgabe zu erfassen sowie eine diesbezügliche Involvierung parietaler Cortexareale zu bestätigen. Zur Erfassung der ego- und allozentrische Navigationsleistung durchliefen Patienten sowie Kontrollpersonen mit dem "virtuellen Labyrinth" und dem "virtuellen Park" zwei unterschiedliche dreidimensionale Testumgebungen. Um diese neuropsychologischen Variablen mit neuronanatomischen Variablen - dem Parietallappen - assoziieren zu können, wurden zudem die Cortices der Probanden mit Hilfe eines Magnetresonanztomographen erfasst. Explorativ wurde zum einen die Beteiligung hippocampaler Areale untersucht, zum anderen wurde innerhalb einer Subgruppenanalyse geprüft, ob sich differentielle neuropsychologische und hirnanatomische Profile bei den verschiedenen schizophrenen Subtypen beobachten ließen. Zudem kamen zur Erzielung einer besseren Vergleichbarkeit zwei klassische neuropsychologische Testinstrumente zum Einsatz, in denen schizophrene Patienten typischerweise Defizite aufweisen: Die Wechsler Memory Scale-Revised sowie der Trail Making Test A und B. Die zentralen Versuchshypothesen konnten bestätigt werden: Schizophrene Patienten wiesen sowohl im ego-, als auch im allozentrischen Raum eine defizitäre Navigationsleistung auf, die der von gesunden Kontrollpersonen unterlegen war. Darüber hinaus ließen sich in der Patientengruppe Volumenreduktionen im globalen und superioren Parietalcortex nachweisen. Die (reduzierten) parietalen Cortexvolumina der schizophrenen Probandengruppe standen des Weiteren in einem funktionalen Zusammenhang zu den beobachteten Navigationsdefiziten: Je kleiner die parietalen Cortexvoluminae waren, desto schlechter war auch die Navigationsleistung im ego- und allozentrischen Raum. Innerhalb der explorativen Analyse zeigte sich bei den schizophrenen Probanden eine deutlich bilaterale Volumenreduktion der Hippocampi. Zusammenhänge zu (defizitären) ego- oder allozentrischen Navigationsleistungen ließen sich allerdings nicht feststellen. Die Subtypenanalyse wies des Weiteren darauf hin, dass paranoide Patienten vor allem Navigationsdefizite im egozentrischen Raum aufwiesen, während desorganisierte Patienten eher durch Schwierigkeiten im allozentrischen Raum charakterisiert waren. Die parietalen Volumina unterschieden sich zwischen den schizophrenen Subgruppen nicht signifikant. Schließlich zeigte sich im Rahmen der klassischen neuropsychologischen Testung, dass schizophrene Patienten starke Defizite in mnestischen und psychomotorischen Funktionen aufwiesen. Insgesamt liefert die vorliegende Arbeit Belege für defizitäre ego- und allozentrische Navigationsleistungen bei der Schizophrenie sowie eine diesbezügliche pathologische Involvierung parietaler Cortexareale

Impaired egocentric memory and reduced somatosensory cortex size in temporal lobe epilepsy with hippocampal sclerosis

Recent research indicates that longstanding temporal lobe epilepsy (TLE) is associated with extratemporal, i.e. parietal cortex damage. We investigated egocentric and allocentric memory by use of first-person large-scale virtual reality environments in patients with TLE. We expected that TLE patients with parietal cortex damage were impaired in the egocentric memory task. Twenty-two TLE patients with hippocampal sclerosis (HS) and 22 TLE patients without HS were compared with 42 healthy matched controls on two virtual reality tasks affording to learn a virtual park (allocentric memory) and a virtual maze (egocentric memory). Participants further received a neuropsychological investigation and MRI volumetry at the time of the assessment. When compared with controls, TLE patients with HS had significantly reduced size of the ipsilateral and contralateral somatosensory cortex (postcentral gyrus). When compared with controls or TLE patients without HS, TLE patients with HS were severely impaired learning the virtual maze. Considering all participants, smaller volumes of the left-sided postcentral gyrus were related to worse performance on the virtual maze. It is concluded that the paradigm of egocentric navigation and learning in first-person large-scale virtual environments may be a suitable tool to indicate significant extratemporal damage in individuals with TLE

Reduced amygdalar and hippocampal size in adults with generalized social phobia

BACKGROUND: Structural and functional brain imaging studies suggest abnormalities of the amygdala and hippocampus in posttraumatic stress disorder and major depressive disorder. However, structural brain imaging studies in social phobia are lacking. METHODS: In total, 24 patients with generalized social phobia (GSP) and 24 healthy controls underwent 3-dimensional structural magnetic resonance imaging of the amygdala and hippocampus and a clinical investigation. RESULTS: Compared with controls, GSP patients had significantly reduced amygdalar (13%) and hippocampal (8%) size. The reduction in the size of the amygdala was statistically significant for men but not women. Smaller right-sided hippocampal volumes of GSP patients were significantly related to stronger disorder severity. LIMITATIONS: Our sample included only patients with the generalized subtype of social phobia. Because we excluded patients with comorbid depression, our sample may not be representative. CONCLUSION: We report for the first time volumetric results in patients with GSP. Future assessment of these patients will clarify whether these changes are reversed after successful treatment and whether they predict treatment response

Egocentric virtual maze learning in adult survivors of childhood abuse with dissociative disorders: Evidence from functional magnetic resonance imaging

Present neuroimaging findings suggest two subtypes of trauma response, one characterized predominantly by hyperarousal and intrusions, and the other primarily by dissociative symptoms. The neural underpinnings of these two subtypes need to be better defined. Fourteen women with childhood abuse and the current diagnosis of dissociative amnesia or dissociative identity disorder but without posttraumatic stress disorder (PTSD) and 14 matched healthy comparison subjects underwent functional magnetic resonance imaging (fMRI) while finding their way in a virtual maze. The virtual maze presented a first-person view (egocentric), lacked any topographical landmarks and could be learned only by using egocentric navigation strategies. Participants with dissociative disorders (DD) were not impaired in learning the virtual maze when compared with controls, and showed a similar, although weaker, pattern of activity changes during egocentric learning when compared with controls. Stronger dissociative disorder severity of participants with DD was related to better virtual maze performance, and to stronger activity increase within the cingulate gyrus and the precuneus. Our results add to the present knowledge of preserved attentional and visuospatial mnemonic functioning in individuals with DD

Medium-term and peri-lockdown course of psychosocial burden during the ongoing COVID-19 pandemic: a longitudinal study on patients with pre-existing mental disorders

While the COVID-19 pandemic continues, patients with pre-existing mental disorders are increasingly recognized as a risk group for adverse outcomes. However, data are conflicting and cover only short time spans so far. Here, we investigate the medium-term and peri-lockdown-related changes of mental health outcomes in such patients in a longitudinal study. A cohort of 159 patients comprising all major mental disorders (ICD-10 F0-F9) were interviewed twice with the Goettingen psychosocial Burden and Symptom Inventory (Goe-BSI) to evaluate psychosocial burden, psychiatric symptoms and resilience at the end of the first (April/May 2020) and the second lockdown in Germany (November/December 2020). For the primary outcome "psychosocial burden" ratings also comprised retrospective pre-pandemic (early 2020) and very early states during the pandemic (March 2020). For all diagnostic groups, psychosocial burden varied significantly over time (p < 0.001) with an increase from the pre-pandemic to the initial phase (p < 0.001), followed by a steady decrease across both lockdowns, normalizing in November/December 2020. Female gender, high adjustment disorder symptom load at baseline and psychiatric comorbidities were risk factors for higher levels and an unfavorable course of psychosocial burden. Most psychiatric symptoms changed minimally, while resilience decreased over time (p = 0.044 and p = 0.037). The longitudinal course of psychosocial burden indicates an initial stress response, followed by a return to pre-pandemic levels even under recurrent lockdown conditions, mimicking symptoms of an adjustment disorder. Strategies for proactive, specific and continuous treatment have to address resilience capacities before their depletion in the pandemic aftermath, especially for patients with additional risk factors