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Childhood adversity is associated with poor mental and physical health outcomes across the life span. Alterations in the hypothalamic–pituitary–adrenal axis are considered a key mechanism underlying these associations, although findings have been mixed. These inconsistencies suggest that other aspects of stress processing may underlie variations in this these associations, and that differences in adversity type, sex, and age may be relevant. The current study investigated the relationship between childhood adversity, stress perception, and morning cortisol, and examined whether differences in adversity type (generalized vs. threat and deprivation), sex, and age had distinct effects on these associations. Salivary cortisol samples, daily hassle stress ratings, and retrospective measures of childhood adversity were collected from a large sample of youth at risk for serious mental illness including psychoses (n = 605, mean age = 19.3). Results indicated that childhood adversity was associated with increased stress perception, which subsequently predicted higher morning cortisol levels; however, these associations were specific to threat exposures in females. These findings highlight the role of stress perception in stress vulnerability following childhood adversity and highlight potential sex differences in the impact of threat exposures.
Migrant youths endure many challenges. Such challenges can be stressful and lead to psychological difficulties. We investigated the relationship between migration, psychopathology and stressful events in children and adolescents. We hypothesised that migrant youths would show higher levels of psychopathology and more stressful life events than non-migrant youths.
Using the Child cohort (Cohort ‘98) of the ‘Growing up in Ireland’ study we investigated psychopathology, as measured by the Strengths and Difficulties questionnaire (SDQ) at age 9 and 13 and stressful life events in migrant and non-migrant youths.
There was no significant difference between the proportion of migrant and non-migrant youths reporting psychopathology in childhood (p>0.05) or adolescence (p>0.05). Analysis of the SDQ subscales revealed that a significantly greater proportion of migrant youths had hyperactivity problems in childhood (p = 0.04) but a greater proportion of non-migrant youths had emotional problems in early adolescence (p = 0.04). We found that migrant youths experienced significantly more stressful life events than their non-migrant counterparts (p<0.01), however, once ‘Moving house/country‘ was removed as a stressor, there was no difference between the groups (p>0.27).
Contrary to our hypothesis, we observed that there were few differences between migrant and non-migrant youths in the levels of psychopathology. Migrant youths experienced a greater number of stressful life events, however, this was attributable to stressors relating to moving. An increased understanding of the factors promoting resilience, as demonstrated by the migrant youths, could aid health professionals and policy makers to effectively tailor interventions for mental health promotion.
We give the first polynomial upper bound on the mixing time of the edge-flip Markov chain for unbiased dyadic tilings, resolving an open problem originally posed by Janson, Randall and Spencer in 2002 . A dyadic tiling of size n is a tiling of the unit square by n non-overlapping dyadic rectangles, each of area 1/n, where a dyadic rectangle is any rectangle that can be written in the form [a2−s, (a + 1)2−s] × [b2−t, (b + 1)2−t] for a, b, s, t ∈ ℤ⩾ 0. The edge-flip Markov chain selects a random edge of the tiling and replaces it with its perpendicular bisector if doing so yields a valid dyadic tiling. Specifically, we show that the relaxation time of the edge-flip Markov chain for dyadic tilings is at most O(n4.09), which implies that the mixing time is at most O(n5.09). We complement this by showing that the relaxation time is at least Ω(n1.38), improving upon the previously best lower bound of Ω(n log n) coming from the diameter of the chain.
Much of the interest in youth at clinical high risk (CHR) of psychosis has been in understanding conversion. Recent literature has suggested that less than 25% of those who meet established criteria for being at CHR of psychosis go on to develop a psychotic illness. However, little is known about the outcome of those who do not make the transition to psychosis. The aim of this paper was to examine clinical symptoms and functioning in the second North American Prodrome Longitudinal Study (NAPLS 2) of those individuals whose by the end of 2 years in the study had not developed psychosis.
In NAPLS-2 278 CHR participants completed 2-year follow-ups and had not made the transition to psychosis. At 2-years the sample was divided into three groups – those whose symptoms were in remission, those who were still symptomatic and those whose symptoms had become more severe.
There was no difference between those who remitted early in the study compared with those who remitted at one or 2 years. At 2-years, those in remission had fewer symptoms and improved functioning compared with the two symptomatic groups. However, all three groups had poorer social functioning and cognition than healthy controls.
A detailed examination of the clinical and functional outcomes of those who did not make the transition to psychosis did not contribute to predicting who may make the transition or who may have an earlier remission of attenuated psychotic symptoms.
Prenatal inflammation is an established risk factor for schizophrenia. However, the specific inflammatory pathways that mediate this association remain unclear. Potential candidate systems include inflammatory markers produced by microglia, such as cytokines and complement. Accumulating evidence suggests that these markers play a role in typical neurodevelopmental processes, such as synapse formation and interneuron migration. Rodent models demonstrate that altered marker levels during the prenatal period can cause lasting deficits in these systems, leading to cognitive deficits that resemble schizophrenia. This review assesses the potential role of prenatal cytokine and complement elevations on the etiology of schizophrenia. The current neurobiological understanding of the development of schizophrenia is reviewed to identify candidate cellular mechanisms that may be influenced by prenatal inflammation. We discuss the functions that cytokines and complement may play in prenatal neurodevelopment, review evidence that links exposure to these factors with risk for schizophrenia, and consider how these markers may interact with genetic vulnerabilities to influence the neurodevelopment of schizophrenia. We consider how prenatal inflammatory exposure may influence childhood and adolescent developmental risk trajectories for schizophrenia. Finally, we identify areas of further research needed to support the development of anti-inflammatory treatments to prevent the development of schizophrenia in at-risk neonates.
Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88) presented a critique of our recently published paper in Cell Reports entitled ‘Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets’ (Lam et al., Cell Reports, Vol. 21, 2017, 2597–2613). Specifically, Hill offered several interrelated comments suggesting potential problems with our use of a new analytic method called Multi-Trait Analysis of GWAS (MTAG) (Turley et al., Nature Genetics, Vol. 50, 2018, 229–237). In this brief article, we respond to each of these concerns. Using empirical data, we conclude that our MTAG results do not suffer from ‘inflation in the FDR [false discovery rate]’, as suggested by Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88), and are not ‘more relevant to the genetic contributions to education than they are to the genetic contributions to intelligence’.
To date, Ireland has been a leading light in the provision of youth mental health services. However, cognisant of the efforts of governmental and non-governmental agencies working in youth mental health, there is much to be done. Barriers into care as well as discontinuity of care across the spectrum of services remain key challenges. This editorial provides guidance for the next stage of development in youth mental care and support that will require significant national engagement and resource investment.
Digital image correlation (DIC) in a scanning electron microscope and high-angular resolution electron backscatter diffraction (HREBSD) provide valuable and complementary data concerning local deformation at the microscale. However, standard surface preparation techniques are mutually exclusive, which makes combining these techniques in situ impossible. This paper introduces a new method of applying surface patterning for DIC, namely a urethane microstamp, that provides a pattern with enough contrast for DIC at low accelerating voltages, but is virtually transparent at the higher voltages necessary for HREBSD and conventional EBSD analysis. Furthermore, microstamping is inexpensive and repeatable, and is more suitable to the analysis of patterns from complex surface geometries and larger surface areas than other patterning techniques.
The various techniques for discovering active galaxies are reviewed, the main emphasis being on optical techniques and their application to emission-line galaxies with active nuclei. The three principal sets of selection criteria involve morphology, colours and emission lines. The major extant lists of emission line galaxies are summarized. Problems of detection are discussed, including selection effects and the use of automatic plate measuring machines. The difficulties of generating useful statistics on different classes of objects are highlighted, but no attempt is made in deriving new statistics or to summarize those in the literature.
With present day technology the technique which provides the greatest precision in astrometric and geodetic measurement is Very Long Baseline Interferometry (VLBI) (Robertson, 1975; Dravskykh, 1981; Gubanov, 1983). The precision of present day astrometrical measurements by VLBI exceeds those of the best modern optical observations by an order and a half of magnitude and is capable of further improvement by the future development of phase stable, wide band, global networks and by the future deployment of VLBI antennas in space. Such precision of observation places the technique of VLBI well within the regime of special and general relativity. The present paper presents an analysis of relativistic effects on VLBI measurements with an accuracy of 0.0001 arc seconds.
Our understanding of the complex relationship between schizophrenia symptomatology and etiological factors can be improved by studying brain-based correlates of schizophrenia. Research showed that impairments in value processing and executive functioning, which have been associated with prefrontal brain areas [particularly the medial orbitofrontal cortex (MOFC)], are linked to negative symptoms. Here we tested the hypothesis that MOFC thickness is associated with negative symptom severity.
This study included 1985 individuals with schizophrenia from 17 research groups around the world contributing to the ENIGMA Schizophrenia Working Group. Cortical thickness values were obtained from T1-weighted structural brain scans using FreeSurfer. A meta-analysis across sites was conducted over effect sizes from a model predicting cortical thickness by negative symptom score (harmonized Scale for the Assessment of Negative Symptoms or Positive and Negative Syndrome Scale scores).
Meta-analytical results showed that left, but not right, MOFC thickness was significantly associated with negative symptom severity (βstd = −0.075; p = 0.019) after accounting for age, gender, and site. This effect remained significant (p = 0.036) in a model including overall illness severity. Covarying for duration of illness, age of onset, antipsychotic medication or handedness weakened the association of negative symptoms with left MOFC thickness. As part of a secondary analysis including 10 other prefrontal regions further associations in the left lateral orbitofrontal gyrus and pars opercularis emerged.
Using an unusually large cohort and a meta-analytical approach, our findings point towards a link between prefrontal thinning and negative symptom severity in schizophrenia. This finding provides further insight into the relationship between structural brain abnormalities and negative symptoms in schizophrenia.
The developmental course of daily functioning prior to first psychosis-onset remains poorly understood. This study explored age-related periods of change in social and role functioning. The longitudinal study included youth (aged 12–23, mean follow-up years = 1.19) at clinical high risk (CHR) for psychosis (converters [CHR-C], n = 83; nonconverters [CHR-NC], n = 275) and a healthy control group (n = 164). Mixed-model analyses were performed to determine age-related differences in social and role functioning. We limited our analyses to functioning before psychosis conversion; thus, data of CHR-C participants gathered after psychosis onset were excluded. In controls, social and role functioning improved over time. From at least age 12, functioning in CHR was poorer than in controls, and this lag persisted over time. Between ages 15 and 18, social functioning in CHR-C stagnated and diverged from that of CHR-NC, who continued to improve (p = .001). Subsequently, CHR-C lagged behind in improvement between ages 21 and 23, further distinguishing them from CHR-NC (p < .001). A similar period of stagnation was apparent for role functioning, but to a lesser extent (p = .007). The results remained consistent when we accounted for the time to conversion. Our findings suggest that CHR-C start lagging behind CHR-NC in social and role functioning in adolescence, followed by a period of further stagnation in adulthood.
Historians of the nineteenth-century Muslim Mediterranean often experience difficulties when they attempt to integrate the study of social or administrative institutions within larger political or intellectual topics. An example of this phenomenon can be found in the history of the Khedivial Law School in Cairo, founded in 1873 and eventually attached to Fuad I University after World War I. The presence of a large number of lawyers within the first twentieth-century Egyptian nationalist movement and in the political life of Egypt up to the end of the constitutional monarchy in 1952 is a well-known fact. As a result, many authors have mentioned the Khedivial Law School, and have tended to give it an historical importance which separates—perhaps in an exaggerated fashion—the study of European law from other professions pursued by young educated Egyptians at the turn of the century, such as that of medicine or military science. When certain recent scholars analyse the components of Egyptian nationalist politics after 1907, therefore, they offer an image of the law school which goes beyond the general idea we actually possess of its internal development between the reigns of Khedive Ismail (1863–79) and Khedive Abbas I (1892–1914). Fortunately an examination of the European archives and the Arabic press of the period helps fill the most obvious gaps in the historical record. It also allows us to estimate the degree to which we can realistically suggest a connection between the teaching of European law and the emergence of a particularly Egyptian model of nationalist political expression in the twentieth-century Mediterranean Arab World.
Although repeatedly associated with white matter microstructural alterations, bipolar disorder (BD) has been relatively unexplored using complex network analysis. This method combines structural and diffusion magnetic resonance imaging (MRI) to model the brain as a network and evaluate its topological properties. A group of highly interconnected high-density structures, termed the ‘rich-club’, represents an important network for integration of brain functioning. This study aimed to assess structural and rich-club connectivity properties in BD through graph theory analyses.
We obtained structural and diffusion MRI scans from 42 euthymic patients with BD type I and 43 age- and gender-matched healthy volunteers. Weighted fractional anisotropy connections mapped between cortical and subcortical structures defined the neuroanatomical networks. Next, we examined between-group differences in features of graph properties and sub-networks.
Patients exhibited significantly reduced clustering coefficient and global efficiency, compared with controls globally and regionally in frontal and occipital regions. Additionally, patients displayed weaker sub-network connectivity in distributed regions. Rich-club analysis revealed subtly reduced density in patients, which did not withstand multiple comparison correction. However, hub identification in most participants indicated differentially affected rich-club membership in the BD group, with two hubs absent when compared with controls, namely the superior frontal gyrus and thalamus.
This graph theory analysis presents a thorough investigation of topological features of connectivity in euthymic BD. Abnormalities of global and local measures and network components provide further neuroanatomically specific evidence for distributed dysconnectivity as a trait feature of BD.
It came as a great surprise that many dwarf elliptical galaxies of very low surface brightness in the Virgo Cluster have conspicuous bright star-like nuclei (Reaves 1983, Binggeli, Sandage and Tammann 1985). These nuclei are at least a factor of 10 more luminous than the brightest globular clusters in the Local Group and comparable only to the very brightest globulars surrounding M87. They contain a considerable fraction (1 to 20%) of the total light of the parent galaxy (Binggeli, priv. commun.). Their physical nature and origin are a matter of debate (Zinnecker et al. 1985, van den Bergh 1985, Norman 1986, Zinnecker 1986) but optical spectroscopy for 3 objects indicates a stellar composition with a range similar to globular clusters (Bothun et al. 1985). It has been suggested that a central nucleus is formed when off-center bound star clusters migrate to the center as a consequence of dynamical friction (Norman 1986). Support for such a scenario comes from CCD observations of IC 3475 which reveal numerous knots near the center of this dwarf irregular galaxy (Vigroux et al. 1986). These knots have the same color as the parent galaxy and are interpreted as intermediate age star clusters.
This small cluster is situated in the western region of the SMC at α = 0h 26m 13s, ε = −73°, 1′, 20″ (1950) and has been chosen for study in the initial post-launch period of the Hubble Space Telescope. This preliminary study was made using data obtained using a CCD camera on the SAAO 1 m telescope in October 1984.
We present preliminary results from a study of the radial velocities of red horizontal branch stars in the north-eastern outer parts of the Small Magellanic Cloud (SMC). The sample is located in an area with a large line-of-sight depth of 15 kpc. It is suggested that there is a correlation between line-of-sight distance and radial velocity for these stars, with the more distant ones showing significantly higher velocities.
This paper presents a color magnitude diagram for the enigmatic cluster ω Centauri (NGC 5139 = C1328 − 472) tracing the main sequence down to V ~ 21.5. The spread in color on the upper main sequence is confirmed as intrinsic to the cluster. The CCD observations were made using the SAAO 1 m telescope with the UCL CCD camera and the RGO CCD camera at the prime focus of the AAT.