Showing papers by "Evangelos Vassos published in 2023"

Genetic examination of the Mood Disorder Questionnaire and its relationship with bipolar disorder.

Abstract: The Mood Disorder Questionnaire (MDQ) is a common screening tool for bipolar disorder that assesses manic symptoms. Its utility for genetic studies of mania or bipolar traits has not been fully examined. We psychometrically compared the MDQ to self-reported bipolar disorder in participants from the United Kingdom National Institute of Health and Care Research Mental Health BioResource. We conducted genome-wide association studies of manic symptom quantitative traits and symptom subgroups, derived from the MDQ items (N = 11,568-19,859). We calculated genetic correlations with bipolar disorder and other psychiatric and behavioral traits. The MDQ screener showed low positive predictive value (0.29) for self-reported bipolar disorder. Neither concurrent nor lifetime manic symptoms were genetically correlated with bipolar disorder. Lifetime manic symptoms had a highest genetic correlation (rg = 1.0) with posttraumatic stress disorder although this was not confirmed by within-cohort phenotypic correlations (rp = 0.41). Other significant genetic correlations included attention deficit hyperactivity disorder (rg = 0.69), insomnia (rg = 0.55), and major depressive disorder (rg = 0.42). Our study adds to existing literature questioning the MDQ's validity and suggests it may capture symptoms of general distress or psychopathology, rather than hypomania/mania specifically, in at-risk populations.

Millimetre-wave Phase Shifting Metasurface Element Enabled by Air-Bridged Schottky Diodes With Enhanced Performance

Abstract: A parasitic element coupling technique is applied within the framework of this paper in order to improve the response of a tunable split patch unit cell. The initial design comprises a split patch with a Schottky diode in contact with both patches, modifying the total impedance under various bias voltages. The paramount goal of the study presented in this paper is the mitigation of losses of the resonances and increase of tuning range by exploiting the presence in the unit cell of an additional parasitic non-resonant element. As a result, the unit cell exhibits double the tuning range of the initial design with lower losses. CST Microwave Studio was used to evaluate the proposed design's tuning range and reflection characteristics.

The association between reasons for first using cannabis, later pattern of use, and risk of first-episode psychosis: the EU-GEI case-control study.

Abstract: BACKGROUND While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis. METHODS We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case-control study. 558 first-episode psychosis patients (FEPp) and 567 population controls who had used cannabis and reported their RFUC.We ran logistic regressions to examine whether RFUC were associated with first-episode psychosis (FEP) case-control status. Path analysis then examined the relationship between RFUC, subsequent patterns of cannabis use, and case-control status. RESULTS Controls (86.1%) and FEPp (75.63%) were most likely to report 'because of friends' as their most common RFUC. However, 20.1% of FEPp compared to 5.8% of controls reported: 'to feel better' as their RFUC (χ2 = 50.97; p < 0.001). RFUC 'to feel better' was associated with being a FEPp (OR 1.74; 95% CI 1.03-2.95) while RFUC 'with friends' was associated with being a control (OR 0.56; 95% CI 0.37-0.83). The path model indicated an association between RFUC 'to feel better' with heavy cannabis use and with FEPp-control status. CONCLUSIONS Both FEPp and controls usually started using cannabis with their friends, but more patients than controls had begun to use 'to feel better'. People who reported their reason for first using cannabis to 'feel better' were more likely to progress to heavy use and develop a psychotic disorder than those reporting 'because of friends'.

What's UPDOG? A novel tool for trans-ancestral polygenic score prediction

Abstract: Polygenic scores provide an indication of an individual's genetic propensity for a trait within a test population. These scores are calculated using results from genetic analysis conducted in discovery populations. However, when the test and discovery populations have different ancestries, predictions are less accurate. As many genetic analyses are conducted using European populations, this hinders the potential for making predictions in many of the underrepresented populations in research. To address this, UP and Downstream Genetic scoring (UPDOG) was developed to consider the genetic architecture of both the discovery and test cohorts before calculating polygenic scores. UPDOG was tested across four ancestries and six phenotypes and benchmarked against five existing tools for polygenic scoring. In approximately two-thirds of cases UPDOG improved trans-ancestral prediction, although the increases were small. Maximising the efficacy of polygenic scores and extending it to the global population is crucial for delivering personalised medicine and universal healthcare equality.

Multifunction Tunable Piezoelectric‐Actuated Metasurface at Millimeter‐Waves

Abstract: Free space (also termed quasi-optical) metasurfaces have recently been designed and proposed as new types of polarizers that allow polarization control of an impinging wave in ways that are not possible with conventional designs. However, existing methods for tunable metasurface polarizers are not able to fully control the polarization dynamically; additionally, at mm-wave and submillimeter bands, they typically suffer from high losses, which are predominantly produced by the inherent limitations of the tuning elements or materials. An electromechanically tunable reflection polariser that has the ability to fully control the polarization of an impinging wave has been designed, fabricated, and experimentally tested in a frequency band centered at 57 GHz. The proposed technique utilizes a variable air cavity between a periodic metasurface array and a ground plane, controlled by a piezoelectric actuator. The periodic metasurface element consists of two slightly different cross-shaped metallic elements arranged in a periodic triangular lattice. Full-wave simulations are presented and experimentally validated with measurements. The proposed approach is scalable from microwave up to THz frequencies with low-loss performance due to the nature of the tuning technology whereby the tuning element is not interfering with the electromagnetic waves in the structure.

A Comparative Study of a Reflectarray Antenna Based on Optical Transparent Materials

Abstract: Reflectarray antennas and Intelligent Reflection Surfaces (IRSs) are key elements in 5G and beyond cellular networks. Optical transparency of the aforementioned structures can increase their potential applications. The transparency of the surface can be achieved by using materials such as indium tin oxide (ITO) and quartz. However, the use of very thin layers of low-conductivity materials can significantly increase the complexity of the electromagnetic simulations. A comparative study that includes simulations of a reflectarray antenna using CST microwave studio and QUPES has been conducted. Simulations suggest a reflectarray with directivity of 26.2 dBi at 60 GHz which is suitable for 5G and Beyond Wireless Networks or emerging Satellite Networks.

Prediction of transition to psychosis from an at-risk mental state using structural neuroimaging, genetic, and environmental data

Abstract: Introduction Psychosis is usually preceded by a prodromal phase in which patients are clinically identified as being at in an “At Risk Mental State” (ARMS). A few studies have demonstrated the feasibility of predicting psychosis transition from an ARMS using structural magnetic resonance imaging (sMRI) data and machine learning (ML) methods. However, the reliability of these findings is unclear due to possible sampling bias. Moreover, the value of genetic and environmental data in predicting transition to psychosis from an ARMS is yet to be explored. Methods In this study we aimed to predict transition to psychosis from an ARMS using a combination of ML, sMRI, genome-wide genotypes, and environmental risk factors as predictors, in a sample drawn from a pool of 246 ARMS subjects (60 of whom later transitioned to psychosis). First, the modality-specific values in predicting transition to psychosis were evaluated using several: (a) feature types; (b) feature manipulation strategies; (c) ML algorithms; (d) cross-validation strategies, as well as sample balancing and bootstrapping. Subsequently, the modalities whose at least 60% of the classification models showed an balanced accuracy (BAC) statistically better than chance level were included in a multimodal classification model. Results and discussion Results showed that none of the modalities alone, i.e., neuroimaging, genetic or environmental data, could predict psychosis from an ARMS statistically better than chance and, as such, no multimodal classification model was trained/tested. These results suggest that the value of structural MRI data and genome-wide genotypes in predicting psychosis from an ARMS, which has been fostered by previous evidence, should be reconsidered.

Cannabis use as a potential mediator between childhood adversity and first-episode psychosis: results from the EU-GEI case–control study

Abstract: Childhood adversity and cannabis use are considered independent risk factors for psychosis, but whether different patterns of cannabis use may be acting as mediator between adversity and psychotic disorders has not yet been explored. The aim of this study is to examine whether cannabis use mediates the relationship between childhood adversity and psychosis. Data were utilised on 881 first-episode psychosis patients and 1231 controls from the European network of national schizophrenia networks studying Gene–Environment Interactions (EU-GEI) study. Detailed history of cannabis use was collected with the Cannabis Experience Questionnaire. The Childhood Experience of Care and Abuse Questionnaire was used to assess exposure to household discord, sexual, physical or emotional abuse and bullying in two periods: early (0–11 years), and late (12–17 years). A path decomposition method was used to analyse whether the association between childhood adversity and psychosis was mediated by (1) lifetime cannabis use, (2) cannabis potency and (3) frequency of use. The association between household discord and psychosis was partially mediated by lifetime use of cannabis (indirect effect coef. 0.078, s.e. 0.022, 17%), its potency (indirect effect coef. 0.059, s.e. 0.018, 14%) and by frequency (indirect effect coef. 0.117, s.e. 0.038, 29%). Similar findings were obtained when analyses were restricted to early exposure to household discord. Harmful patterns of cannabis use mediated the association between specific childhood adversities, like household discord, with later psychosis. Children exposed to particularly challenging environments in their household could benefit from psychosocial interventions aimed at preventing cannabis misuse.

Tuneable millimetre-wave leaky wave antenna based on Air-bridged Schottky diodes

Abstract: A novel beam-steering antenna based on airbridged Schottky diodes is proposed for emerging millimetre wave technologies such as 5G/6G. The primary radiating structure is a metasurface-based leaky-wave antenna (LWA), including a tuneable high impedance surface (HIS) ground plane. The HIS phase variation is accomplished by varying the capacitance of air-bridged Schottky diodes embedded into the periodic elements of the HIS. The proposed antenna operates at 43.5 GHz with a continuous beam scanning of 20°. The fast (in the order of ns) and continuous beam steering are the key advantages of the proposed metasurface-based antenna. Simulations have been carried out using CST Microwave Studio to evaluate the performance of the beam-steering antenna.