A transdiagnostic comparison of hallucinations

Hallucinations present in a wide range of clinical disorders, including psychiatric, neurological and other medical disorders. Hallucinations also occur in a minority of the general population. As hallucinations are not unique to one disorder, there has been growing consensus that hallucinations should be investigated using a broader transdiagnostic approach. Transdiagnostic research is currently hindered due to the lack of a suitable measurement tool. In part I of the thesis, a new transdiagnostic questionnaire - the Questionnaire for Psychotic experiences (QPE) - was developed. The QPE enables assessment of severity, frequency and phenomenology of psychotic experiences across disorders. The results showed that participants with various disorders reported hallucinations, which confirms that hallucinations should be considered a transdiagnostic phenomenon. A comparison of hallucinations across disorders confirmed previous findings that similar phenomenological characteristics can exist between disorders, and that phenomenological characteristics can differ within a diagnosis. This suggests the existence of subtypes of hallucinations that transcend diagnosis.In part II of the thesis, the neural mechanism of hallucinations was investigated across participants with a schizophrenia-spectrum disorder, bipolar disorder and non-clinical individuals. Previous studies report similar phenomenological characteristics of hallucinations across these participants, suggesting a similar underlying neural mechanism. Our results do not support this hypothesis. Non-clinical individuals and schizophrenia patients with hallucinations show similar alterations of the functional connectome, whereas differential alterations were reported for bipolar disorder patients with hallucinations. This suggests a different underlying neural mechanism for hallucinations in bipolar disorder as compared to non-clinical individuals and patients with schizophrenia

Lower fractional anisotropy without evidence for neuro-inflammation in patients with early-phase schizophrenia spectrum disorders

Various lines of research suggest immune dysregulation as a potential therapeutic target for negative and cognitive symptoms in schizophrenia spectrum disorders (SSD). Immune dysregulation would lead to higher extracellular free-water (EFW) in cerebral white matter (WM), which may partially underlie the frequently reported lower fractional anisotropy (FA) in SSD. We aim to investigate differences in EFW concentrations – a presumed proxy for neuro-inflammation – between early-phase SSD patients (n = 55) and healthy controls (HC; n = 37), and to explore immunological and cognitive correlates. To increase specificity for EFW, we study several complementary magnetic resonance imaging contrasts that are sensitive to EFW. FA, mean diffusivity (MD), magnetization transfer ratio (MTR), myelin water fraction (MWF) and quantitative T1 and T2 were calculated from diffusion-weighted imaging (DWI), magnetization transfer imaging (MTI) and multicomponent driven equilibrium single-pulse observation of T1/T2 (mcDESPOT). For each measure, WM skeletons were constructed with tract-based spatial statistics. Multivariate SSD-HC comparisons with WM skeletons and their average values (i.e. global WM) were not statistically significant. In voxel-wise analyses, FA was significantly lower in SSD in the genu of the corpus callosum and in the left superior longitudinal fasciculus (p < 0.04). Global WM measures did not correlate with immunological markers (i.e. IL1-RA, IL-6, IL-8, IL-10 and CRP) or cognition in HC and SSD after corrections for multiple comparisons. We confirmed lower FA in early-phase SSD patients. However, non–FA measures did not provide additional evidence for immune dysregulation or for higher EFW as the primary mechanism underlying the reported lower FA values in SSD

Functional brain networks in the schizophrenia spectrum and bipolar disorder with psychosis

Psychotic experiences have been proposed to lie on a spectrum, ranging from subclinical experiences to treatment-resistant schizophrenia. We aimed to characterize functional connectivity and brain network characteristics in relation to the schizophrenia spectrum and bipolar disorder with psychosis to disentangle neural correlates to psychosis. Additionally, we studied antipsychotic medication and lithium effects on network characteristics. We analyzed functional connectivity strength and network topology in 487 resting-state functional MRI scans of individuals with schizophrenia spectrum disorder (SCZ), bipolar disorder with a history of psychotic experiences (BD), treatment-naïve subclinical psychosis (SCP), and healthy controls (HC). Since differences in connectivity strength may confound group comparisons of brain network topology, we analyzed characteristics of the minimum spanning tree (MST), a relatively unbiased backbone of the network. SCZ and SCP subjects had a lower connectivity strength than BD and HC individuals but showed no differences in network topology. In contrast, BD patients showed a less integrated network topology but no disturbances in connectivity strength. No differences in outcome measures were found between SCP and SCZ, or between BD patients that used antipsychotic medication or lithium and those that did not. We conclude that functional networks in patients prone to psychosis have different signatures for chronic SCZ patients and SCP compared to euthymic BD patients, with a limited role for medication. Connectivity strength effects may have confounded previous studies, as no functional network alterations were found in SCZ after strict correction for connectivity strength.</p

Interactive detection of incrementally learned concepts in images with ranking and semantic query interpretation

This research was performed in the GOOSE project, which is jointly funded by the MIST research program of the Dutch Ministry of Defense and the AMSN enabling technology program.The number of networked cameras is growing exponentially. Multiple applications in different domains result in an increasing need to search semantically over video sensor data. In this paper, we present the GOOSE demonstrator, which is a real-time general-purpose search engine that allows users to pose natural language queries to retrieve corresponding images. Top-down, this demonstrator interprets queries, which are presented as an intuitive graph to collect user feedback. Bottomup, the system automatically recognizes and localizes concepts in images and it can incrementally learn novel concepts. A smart ranking combines both and allows effective retrieval of relevant images.peer-reviewe

Modular-Level Functional Connectome Alterations in Individuals With Hallucinations Across the Psychosis Continuum

Functional connectome alterations, including modular network organization, have been related to the experience of hallucinations. It remains to be determined whether individuals with hallucinations across the psychosis continuum exhibit similar alterations in modular brain network organization. This study assessed functional connectivity matrices of 465 individuals with and without hallucinations, including patients with schizophrenia and bipolar disorder, nonclinical individuals with hallucinations, and healthy controls. Modular brain network organization was examined at different scales of network resolution, including (1) global modularity measured as Qmax and Normalised Mutual Information (NMI) scores, and (2) within- and between-module connectivity. Global modular organization was not significantly altered across groups. However, alterations in within- and between-module connectivity were observed for higher-order cognitive (e.g., central-executive salience, memory, default mode), and sensory modules in patients with schizophrenia and nonclinical individuals with hallucinations relative to controls. Dissimilar patterns of altered within- and between-module connectivity were found bipolar disorder patients with hallucinations relative to controls, including the visual, default mode, and memory network, while connectivity patterns between visual, salience, and cognitive control modules were unaltered. Bipolar disorder patients without hallucinations did not show significant alterations relative to controls. This study provides evidence for alterations in the modular organization of the functional connectome in individuals prone to hallucinations, with schizophrenia patients and nonclinical individuals showing similar alterations in sensory and higher-order cognitive modules. Other higher-order cognitive modules were found to relate to hallucinations in bipolar disorder patients, suggesting differential neural mechanisms may underlie hallucinations across the psychosis continuum.publishedVersio

Auditory hallucinations, top-down processing and language perception: a general population study

Background: Studies investigating the underlying mechanisms of hallucinations in patients with schizophrenia suggest that an imbalance in top-down expectations v. bottom-up processing underlies these errors in perception. This study evaluates this hypothesis by testing if individuals drawn from the general population who have had auditory hallucinations (AH) have more misperceptions in auditory language perception than those who have never hallucinated. Methods: We used an online survey to determine the presence of hallucinations. Participants filled out the Questionnaire for Psychotic Experiences and participated in an auditory verbal recognition task to assess both correct perceptions (hits) and misperceptions (false alarms). A hearing test was performed to screen for hearing problems. Results: A total of 5115 individuals from the general Dutch population participated in this study. Participants who reported AH in the week preceding the test had a higher false alarm rate in their auditory perception compared with those without such (recent) experiences. The more recent the AH were experienced, the more mistakes participants made. While the presence of verbal AH (AVH) was predictive for false alarm rate in auditory language perception, the presence of non-verbal or visual hallucinations were not. Conclusions: The presence of AVH predicted false alarm rate in auditory language perception, whereas the presence of non-verbal auditory or visual hallucinations was not, suggesting that enhanced top-down processing does not transfer across modalities. More false alarms were observed in participants who reported more recent AVHs. This is in line with models of enhanced influence of top-down expectations in persons who hallucinate.publishedVersio

Author Correction:Functional connectome differences in individuals with hallucinations across the psychosis continuum (Scientific Reports, (2021), 11, 1, (1108), 10.1038/s41598-020-80657-8)

The Supplementary Information published with this Article contained an error, where an old version of Figure S5 was used. This error has now been corrected in the Supplementary Information file that accompanies the original Article. The corrected Supplementary Information file is also linked to this correction notices.</p

Author Correction:Functional connectome differences in individuals with hallucinations across the psychosis continuum (Scientific Reports, (2021), 11, 1, (1108), 10.1038/s41598-020-80657-8)

The Supplementary Information published with this Article contained an error, where an old version of Figure S5 was used. This error has now been corrected in the Supplementary Information file that accompanies the original Article. The corrected Supplementary Information file is also linked to this correction notices

Functional connectome differences in individuals with hallucinations across the psychosis continuum

Hallucinations may arise from an imbalance between sensory and higher cognitive brain regions, reflected by alterations in functional connectivity. It is unknown whether hallucinations across the psychosis continuum exhibit similar alterations in functional connectivity, suggesting a common neural mechanism, or whether different mechanisms link to hallucinations across phenotypes. We acquired resting-state functional MRI scans of 483 participants, including 40 non-clinical individuals with hallucinations, 99 schizophrenia patients with hallucinations, 74 bipolar-I disorder patients with hallucinations, 42 bipolar-I disorder patients without hallucinations, and 228 healthy controls. The weighted connectivity matrices were compared using network-based statistics. Non-clinical individuals with hallucinations and schizophrenia patients with hallucinations exhibited increased connectivity, mainly among fronto-temporal and fronto-insula/cingulate areas compared to controls (P < 0.001 adjusted). Differential effects were observed for bipolar-I disorder patients with hallucinations versus controls, mainly characterized by decreased connectivity between fronto-temporal and fronto-striatal areas (P = 0.012 adjusted). No connectivity alterations were found between bipolar-I disorder patients without hallucinations and controls. Our results support the notion that hallucinations in non-clinical individuals and schizophrenia patients are related to altered interactions between sensory and higher-order cognitive brain regions. However, a different dysconnectivity pattern was observed for bipolar-I disorder patients with hallucinations, which implies a different neural mechanism across the psychosis continuum.publishedVersio

Epidemiology and awareness of hypertension in a rural Ugandan community: a cross-sectional study

BACKGROUND: Hypertension is one of the largest causes of preventable morbidity and mortality worldwide. There are few population-based studies on hypertension epidemiology to guide public health strategies in sub-Saharan Africa. Using a community-based strategy that integrated screening for HIV and non-communicable diseases, we determined the prevalence, awareness, treatment rates, and sociodemographic factors associated with hypertension in rural Uganda. METHODS: A household census was performed to enumerate the population in Kakyerere parish in Mbarara district, Uganda. A multi-disease community-based screening campaign for hypertension, diabetes, and HIV was then conducted. During the campaign, all adults received a blood pressure (BP) measurement and completed a survey examining sociodemographic factors. Hypertension was defined as elevated BP (≥140/≥90 mmHg) on the lowest of three BP measurements or current use of antihypertensives. Prevalence was calculated and standardized to age distribution. Sociodemographic factors associated with hypertension were evaluated using a log-link Poisson regression model with robust standard errors. RESULTS: Community participation in the screening campaign was 65%, including 1245 women and 1007 men. The prevalence of hypertension was 14.6%; awareness of diagnosis (38.1%) and current receipt of treatment (20.6%) were both low. Age-standardized to the WHO world standard population, hypertension prevalence was 19.8%, which is comparable to 21.6% in the US and 18.4% in the UK. Sociodemographic factors associated with hypertension included increasing age, male gender, overweight, obesity, diabetes, alcohol consumption, and family history. Prevalence of modifiable factors was high: 28.3% women were overweight/obese and 24.1% men consumed ≥10 alcoholic drinks per month. CONCLUSIONS: We found a substantial burden of hypertension in rural Uganda. Awareness and treatment of hypertension is low in this region. Enhanced community-based education and prevention efforts tailored to addressing modifiable factors are needed