Publications by authors named "Alexandra Moussa-Tooks"

Background: Negative symptom severity predicts functional outcome and quality life in people with psychosis. However, negative symptoms are poorly responsive to antipsychotic medication and existing literature has not converged on their neurobiological basis. Previous work in small schizophrenia samples has observed that lower cerebellar-prefrontal connectivity is associated with higher negative symptom severity and demonstrated in a separate neuromodulation experiment that increasing cerebellar-prefrontal connectivity reduced negative symptom severity.

View Article and Find Full Text PDF

As clinical psychological science and biological psychiatry push to assess, model, and integrate heterogeneity and individual differences, approaches leveraging computational modeling, translational methods, and dimensional approaches to psychopathology are increasingly useful in establishing brain-behavior relationships. The field is ultimately interested in complex human behavior, and disruptions in such behaviors can arise through many different pathways, leading to heterogeneity in etiology for seemingly similar presentations. Parsing this complexity may be enhanced using "simple" tasks-which we define as those assaying elemental processes that are the building blocks to complexity.

View Article and Find Full Text PDF

Background: Psychomotor disturbances are observed across psychiatric disorders and often manifest as psychomotor slowing, agitation, disorganized behavior, or catatonia. Psychomotor function includes both cognitive and motor components, but the neural circuits driving these subprocesses and how they relate to symptoms have remained elusive for centuries.

Methods: We analyzed data from the HCP-EP (Human Connectome Project for Early Psychosis), a multisite study of 125 participants with early psychosis and 58 healthy participants with resting-state functional magnetic resonance imaging and clinical characterization.

View Article and Find Full Text PDF

Given the culturally diverse landscape of mental healthcare and research, ensuring that our psychological constructs are measured equivalently across diverse populations is critical. One construct for which there is significant potential for inequitable assessment is paranoia, a prominent feature in psychotic disorders that can also be driven by culture and racial marginalization. This study examined measurement invariance-an analytic technique to rigorously investigate whether a given construct is being measured similarly across groups-of the Revised-Green Paranoid Thought Scale (R-GPTS; Freeman et al.

View Article and Find Full Text PDF

Purpose Of Review: Emotions are prominent in theories and accounts of schizophrenia but are largely understudied compared to cognition. Utilizing the Research Domain Criteria (RDoC) Negative Valence Systems framework, we review the current knowledge of emotions in schizophrenia. Given the pivotal role of threat responses in theories of schizophrenia and the substantial evidence of altered threat responses, we focus on three components of Negative Valence Systems tied to threat responses: responses to acute threat, responses to potential threat, and sustained threat.

View Article and Find Full Text PDF

Multiple lines of evidence across human functional, lesion, and animal data point to a cerebellar role, in particular of crus I, crus II, and lobule VIIB, in cognitive function. However, a mapping of distinct facets of cognitive function to cerebellar structure is missing. We analyzed structural neuroimaging data from the Healthy Brain Network (HBN).

View Article and Find Full Text PDF

Race and socioeconomic status (SES) are commonly cited as risk factors for psychosis and psychotic-like experiences (PLEs). However, few studies have investigated the relationships between race and SES with specific domains of PLEs. Specifically, little work has examined the relationships between race and SES with delusional ideation, severity (preoccupation, conviction, distress), and delusional themes.

View Article and Find Full Text PDF

Background: Delusions are a hallmark feature of psychotic disorders and lead to significant clinical and functional impairment. Internalizing symptoms-such as symptoms of depression, anxiety, and trauma exposure-are commonly cited to be related to delusions and delusional ideation and are often associated with deficits in social functioning. While emerging studies are investigating the impact of low social engagement on psychotic-like experiences, little work has examined the relationship between social engagement, internalizing symptoms, and delusional ideation, specifically.

View Article and Find Full Text PDF

Psychomotor disturbance has been identified as a key feature of psychotic disorders, with motor signs observed in upwards of 66% of unmedicated, first-episode patients. Aberrations in the cerebellum have been directly linked to sensorimotor processing deficits including processing speed, which may underly psychomotor disturbance in psychosis, though these brain-behavior-symptom relationships are unclear, in part due to within-diagnosis heterogeneity across these levels of analysis. In 339 psychosis patients (242 schizophrenia-spectrum, 97 bipolar with psychotic features) and 217 controls, we evaluated the relationship between cerebellar grey matter volume in the Yeo sensorimotor network and psychomotor disturbance (mannerisms and posturing, retardation, excitement of the Positive and Negative Syndrome Scale [PANSS]), as mediated by processing speed (assessed via the SCIP).

View Article and Find Full Text PDF

Rationale: Cannabis is the most widely used illicit substance in the USA and is often reportedly used for stress reduction. Indeed, cannabinoids modulate signaling of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. However, the role of biological sex in this interaction between cannabis use and stress is poorly understood, despite sex differences in neurobiological stress responsivity, endocannabinoid signaling, and clinical correlates of cannabis use.

View Article and Find Full Text PDF
Article Synopsis
  • Risk-taking can be beneficial, but individuals with schizophrenia score lower on risky reward pursuits compared to controls, potentially indicating issues in reward processing rather than risk sensitivity.
  • A study involving 60 participants (30 with schizophrenia/schizoaffective disorder) used fMRI during a risk task, revealing that those with schizophrenia showed less activation in the nucleus accumbens during decisions about rewards.
  • The findings suggest that abnormal activation patterns in the reward-processing areas of the brain may contribute to the poor risk-taking behavior observed in individuals with schizophrenia.
View Article and Find Full Text PDF

Background: Dysconnectivity theories, combined with advances in fundamental cognitive neuroscience, have led to increased interest in characterizing cerebellar abnormalities in psychosis. Smaller cerebellar gray matter volume has been found in schizophrenia spectrum disorders. However, the course of these deficits across illness stage, specificity to schizophrenia (vs.

View Article and Find Full Text PDF

There is a dearth of research examining how individual-level and systemic racism may lead to elevated diagnostic and symptom rates of paranoia in Black Americans. The present study employed item response theory methods to investigate item- and subscale-level functioning in the Schizotypal Personality Questionnaire (SPQ) in 388 Black and 450 White participants across the schizophrenia-spectrum (i.e.

View Article and Find Full Text PDF

The cognitive dysmetria theory of psychotic disorders posits that cerebellar circuit abnormalities give rise to difficulties coordinating motor and cognitive functions. However, brain activation during cerebellar-mediated tasks is understudied in schizophrenia. Accordingly, this study examined whether individuals with schizophrenia have diminished neural activation compared to controls in key regions of the delay eyeblink conditioning (dEBC) cerebellar circuit (eg, lobule VI) and cerebellar regions associated with cognition (eg, Crus I).

View Article and Find Full Text PDF

The Sensory Gating Inventory (SGI) is a 36-item measure used to assess an individual's subjective ability to modulate, filter, over-include, discriminate, attend to, and tolerate sensory stimuli. Due to its theoretical and empirical link with sensory processing deficits, this measure has been used extensively in studies of psychosis and other psychopathology. The current work fills a need within the field for a briefer measure of sensory gating aberrations that maintains the original measure's utility.

View Article and Find Full Text PDF

Early life stress paradigms have become prominent in the animal literature to model atypical development. Currently, two models have prevailed within the literature: (1) limited bedding or nesting and (2) maternal separation or deprivation. Both models have produced aberrations spanning behavior and neural circuitry.

View Article and Find Full Text PDF

Emerging evidence points to the role of the endocannabinoid system in long-term stress-induced neural remodeling with studies on stress-induced endocannabinoid dysregulation focusing on cerebral changes that are temporally proximal to stressors. Little is known about temporally distal and sex-specific effects, especially in cerebellum, which is vulnerable to early developmental stress and is dense with cannabinoid receptors. Following limited bedding at postnatal days 2-9, adult (postnatal day 70) cerebellar and hippocampal endocannabinoids, related lipids, and mRNA were assessed, and behavioral performance evaluated.

View Article and Find Full Text PDF

Abnormalities of cerebellar function have been implicated in the pathophysiology of schizophrenia. Since the cerebellum has afferent and efferent projections to diverse brain regions, abnormalities in cerebellar lobules could affect functional connectivity with multiple functional systems in the brain. Prior studies, however, have not examined the relationship of individual cerebellar lobules with motor and nonmotor resting-state functional networks.

View Article and Find Full Text PDF

Perceived nose elongation resulting from vibratory stimulation to the bicep brachii tendon in the absence of visual input while the finger is touching the nose, known as the Pinocchio Illusion (PI), is used to investigate how afferent signals can contribute to aberrant top-down perception of body representation. The Pinocchio Illusion Questionnaire (PIQ) was developed to empirically quantify PI perception, allowing for external validation of the PI with psychologically relevant phenomenon. The current study (N = 60) examined the PIQ's test-retest reliability, internal consistency, factor structure, and correlations with self-reported interoceptive awareness and schizotypal traits.

View Article and Find Full Text PDF

Despite widespread use in schizophrenia-spectrum research, uncertainty remains around an empirically supported and theoretically meaningful factor structure of the Schizotypal Personality Questionnaire (SPQ). Current identified structures are limited by reliance on exclusively nonclinical samples. The current study compared factor structures of the SPQ in a sample of 335 nonpsychiatric individuals, 292 schizotypy-spectrum individuals (schizophrenia, schizoaffective disorder, or schizotypal personality disorder), and the combined group ( = 627).

View Article and Find Full Text PDF

Delay eyeblink conditioning (dEBC) is widely used to assess cerebellar-dependent associative motor learning, including precise timing processes. Transcranial direct current stimulation (tDCS), noninvasive brain stimulation used to indirectly excite and inhibit select brain regions, may be a promising tool for understanding how functional integrity of the cerebellum influences dEBC behavior. The aim of this study was to assess whether tDCS-induced inhibition (cathodal) and excitation (anodal) of the cerebellum differentially impact timing of dEBC.

View Article and Find Full Text PDF