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Subtle alterations in white matter microstructure are observed in youth at clinical high risk (CHR) for psychosis. However, the timing of these changes and their relationships to the emergence of psychosis remain unclear. Here, we track the evolution of white matter abnormalities in a large, longitudinal cohort of CHR individuals comprising the North American Prodrome Longitudinal Study (NAPLS-3). Multi-shell diffusion magnetic resonance imaging data were collected across multiple timepoints (1-5 over 1 year) in 286 subjects (aged 12-32 years): 25 CHR individuals who transitioned to psychosis (CHR-P; 61 scans), 205 CHR subjects with unknown transition outcome after the 1-year follow-up period (CHR-U; 596 scans), and 56 healthy controls (195 scans). Linear mixed effects models were fitted to infer the impact of age and illness-onset on variation in the fractional anisotropy of cellular tissue (FAT) and the volume fraction of extracellular free water (FW). Baseline measures of white matter microstructure did not differentiate between HC, CHR-U and CHR-P individuals. However, age trajectories differed between the three groups in line with a developmental effect: CHR-P and CHR-U groups displayed higher FAT in adolescence, and 4% lower FAT by 30 years of age compared to controls. Furthermore, older CHR-P subjects (20+ years) displayed 4% higher FW in the forceps major (p

Deletions and duplications at the 22q11.2 locus are associated with significant neurodevelopmental and psychiatric morbidity. Previous diffusion-weighted magnetic resonance imaging (MRI) studies in 22q11.2 deletion carriers (22q-del) found nonspecific white matter (WM) abnormalities, characterized by higher fractional anisotropy. Here, utilizing novel imaging and processing methods that allow separation of signal contribution from different tissue properties, we investigate whether higher anisotropy is driven by (1) extracellular changes, (2) selective degeneration of secondary fibers, or (3) volumetric differences. We further, for the first time, investigate WM microstructure in 22q11.2 duplication carriers (22q-dup). Multi-shell diffusion-weighted images were acquired from 26 22q-del, 19 22q-dup, and 18 healthy individuals (HC). Images were fitted with the free-water model to estimate anisotropy following extracellular free-water elimination and with the novel BedpostX model to estimate fractional volumes of primary and secondary fiber populations. Outcome measures were compared between groups, with and without correction for WM and cerebrospinal fluid (CSF) volumes. In 22q-del, anisotropy following free-water elimination remained significantly higher compared with controls. BedpostX did not identify selective secondary fiber degeneration. Higher anisotropy diminished when correcting for the higher CSF and lower WM volumes. In contrast, 22q-dup had lower anisotropy and greater extracellular space than HC, not influenced by macrostructural volumes. Our findings demonstrate opposing effects of reciprocal 22q11.2 copy-number variation on WM, which may arise from distinct pathologies. In 22q-del, microstructural abnormalities may be secondary to enlarged CSF space and more densely packed WM. In 22q-dup, we see evidence for demyelination similar to what is commonly observed in neuropsychiatric disorders.

Abstract Background Studies in individuals at clinical high risk (CHR) for psychosis provide a powerful means to predict outcomes and inform putative mechanisms underlying conversion to psychosis. In previous work, we applied advanced diffusion imaging methods to reveal that white matter pathology in a CHR population is characterized by cellular-specific changes in white matter, suggesting a preexisting neurodevelopmental anomaly. However, it remains unknown whether these deficits relate to clinical symptoms and/or conversion to frank psychosis. To address this gap, we examined cross-sectional and longitudinal white matter maturation in the largest imaging population of CHR individuals to date, obtained from the North American Prodrome Longitudinal Study (NAPLS-3). Methods Multi-shell diffusion magnetic resonance imaging (MRI) data were collected across multiple timepoints (1–6 at ~2 month intervals) in 286 subjects (age range=12–32 years). These were 230 unmedicated CHR subjects, including 11% (n=25) who transitioned to psychosis (CHR-converters), as well as 56 age and sex-matched healthy controls. Raw diffusion signals were harmonized to remove scanner/site-induced effects, yielding a unified imaging dataset. Fractional anisotropy of cellular tissue (FAt) and the volume fraction of extracellular free-water (FW) were assessed in 12 major tracts from the IIT Human Brain Atlas (v.5.0). Linear mixed effects (LME) models were fitted to infer developmental trajectories of FAt and FW across age for CHR-converters, CHR-nonconverters and control groups, while accounting for the repeated measurements on each individual. Results The rate at which FAt changed with age significantly differed between the three groups across commissural and association tracts (5 in total; p

Regular participation in sports results in a series of physiological adaptations. However, little is known about the brain adaptations to physical activity. Here we aimed to investigate whether young endurance athletes and non‐athletes differ in the gray and white matter of the brain and whether cardiorespiratory fitness (CRF) is associated with these differences. We assessed the CRF, volumes of the gray and white matter of the brain using structural magnetic resonance imaging (sMRI), and brain white matter connections using diffusion magnetic resonance imaging (dMRI) in 20 young male endurance athletes and 21 healthy non‐athletes. While total brain volume was similar in both groups, the white matter volume was larger and the gray matter volume was smaller in the athletes compared to non‐athletes. The reduction of gray matter was located in the association areas of the brain that are specialized in processing of sensory stimuli. In the microstructure analysis, significant group differences were found only in the association tracts, for example, the inferior occipito‐frontal fascicle (IOFF) showing higher fractional anisotropy and lower radial diffusivity, indicating stronger myelination in this tract. Additionally, gray and white matter brain volumes, as well as association tracts correlated with CRF. No changes were observed in other brain areas or tracts. In summary, the brain signature of the endurance athlete is characterized by changes in the integration of sensory and motor information in the association areas. This study unveils the intriguing relationship between regular endurance sports participation, brain structure, and cardiorespiratory fitness. The findings shed light on the intricate interplay between physical activity and brain physiology, contributing valuable insights to our understanding of the brain's response to exercise. [ABSTRACT FROM AUTHOR]

Aim: To harmonize two ascertainment and severity rating instruments commonly used for the clinical high risk syndrome for psychosis (CHR‐P): the Structured Interview for Psychosis‐risk Syndromes (SIPS) and the Comprehensive Assessment of At‐Risk Mental States (CAARMS). Methods: The initial workshop is described in the companion report from Addington et al. After the workshop, lead experts for each instrument continued harmonizing attenuated positive symptoms and criteria for psychosis and CHR‐P through an intensive series of joint videoconferences. Results: Full harmonization was achieved for attenuated positive symptom ratings and psychosis criteria, and modest harmonization for CHR‐P criteria. The semi‐structured interview, named Positive SYmptoms and Diagnostic Criteria for the CAARMS Harmonized with the SIPS (PSYCHS), generates CHR‐P criteria and severity scores for both CAARMS and SIPS. Conclusions: Using the PSYCHS for CHR‐P ascertainment, conversion determination, and attenuated positive symptom severity rating will help in comparing findings across studies and in meta‐analyses. [ABSTRACT FROM AUTHOR]

Disrupted auditory networks play an important role in the pathophysiology of psychosis, with abnormalities already observed in individuals at clinical high-risk for psychosis (CHR). Here, we examine structural and functional connectivity of an auditory network in CHR utilising state-of-the-art electroencephalography and diffusion imaging techniques. Twenty-six CHR subjects and 13 healthy controls (HC) underwent diffusion MRI and electroencephalography while performing an auditory task. We investigated structural connectivity, measured as fractional anisotropy in the Arcuate Fasciculus (AF), Cingulum Bundle, and Superior Longitudinal Fasciculus-II. Gamma-band lagged-phase synchronisation, a functional connectivity measure, was calculated between cortical regions connected by these tracts. CHR subjects showed significantly higher structural connectivity in the right AF than HC (p <.001). Although non-significant, functional connectivity between cortical areas connected by the AF was lower in CHR than HC (p =.078). Structural and functional connectivity were correlated in HC (p =.056) but not in CHR (p =.29). We observe significant differences in structural connectivity of the AF, without a concomitant significant change in functional connectivity in CHR subjects. This may suggest that the CHR state is characterised by a decoupling of structural and functional connectivity, possibly due to abnormal white matter maturation. [ABSTRACT FROM AUTHOR]

Background: The 22q11.2 deletion syndrome is a neurogenetic disorder that is associated with both physical anomalies and neurocognitive impairments. Deletion carriers have a greatly elevated risk of developing schizophrenia (SCZ); as such, it offers a compelling ‘high-penetrance’ model to explore the neuropathology of SCZ risk. Indeed, widespread structural alterations of both gray and white matter have been reported for 22q11.2 deletion carriers. Interestingly, there are also cases of duplications at the same gene locus. While less is known about the phenotype associated with 22q11.2 duplication, carriers also present physical and neurodevelopmental abnormalities, although they may have reduced risk of developing SCZ compared to the general population. The only study to date which looked at brain structure in duplication carriers found reciprocal effects of 22q11.2 deletion and duplication on cortical thickness and surface measurements. In the present study, we apply diffusion magnetic resonance imaging (MRI) to examine the white matter microstructure in both 22q11.2 deletion and duplication carriers. Methods: Multi-shell diffusion-weighted images were acquired on a 3 Tesla MRI scanner from 13 healthy control individuals (HC), 25 deletion carriers, and 18 22q11.2 duplication carriers. Images were preprocessed utilizing the Human Connectome Project (HCP) Minimal Preprocessing Pipeline v4.0.0. Free Water imaging was applied, which differentiates the diffusion signal into a free-water compartment and a tissue compartment. The output parameters are the free-water fractional volume (FW) and a free-water corrected diffusion tensor from which fractional anisotropy of the tissue (FAT) is calculated. We compared FAT and FW maps between 1) HC and 22q11.2 deletion carriers and 2) HC and 22q11.2 duplication carriers using Tract-Based Spatial Statistics (TBSS) and voxel-wise, non-parametric statistics (5000 permutations, threshold-free cluster enhancement, corrected for age and sex). Lastly, white matter clusters that displayed significant differences between 22q11.2 deletion or duplication and HC were extracted. We averaged FAT and FW values over these significant clusters for each individual and correlated with the scores of the Structured Interview for Prodromal Syndromes (SIPS). Results: 22q11.2 deletion carriers showed significant (p<0.05) FW reductions (72% of white matter skeleton) and FAT increase (8%) when compared to HC. In contrast, 22q11.2 duplication carriers displayed the opposite effect, with significant (p<0.05) widespread FW increase (51%) and FAT decrease (50%) when compared to HC. Both 22q11.2 deletion and duplication carriers scored higher on the SIPS than HC, with negative symptom score differences being the most pronounced (mean for HC= 1.36, mean for 22q11.2 duplication = 7.0, mean for 22q11.2 deletion =9.96, F=6.68, df=2, p<.003). FAT and FW were not associated with SIPS scores in 22q11.2 deletion syndrome. However, FAT was negatively correlated with the negative symptom score in 22q11.2 duplication carriers (Spearman rho=-.61, p<.009). Discussion: We observed opposing effects of gene-dosage on FAT and FW. While we did not see an association between WM measurements and psychotic symptoms in 22q11.2 deletion, there was an association of WM structure with negative symptoms in 22q11.2 duplication carriers. These findings highlight the importance of studying the influence of reciprocal chromosomal imbalance on white matter architecture. Ongoing longitudinal studies may help advance understanding of the role of microstructural white matter abnormalities in the emergence of neuropsychiatric symptoms. [ABSTRACT FROM AUTHOR]

Background: Studies in individuals at clinical high risk (CHR) for psychosis provide a powerful means to predict outcomes and inform putative mechanisms underlying conversion to psychosis. In previous work, we applied advanced diffusion imaging methods to reveal that white matter pathology in a CHR population is characterized by cellular-specific changes in white matter, suggesting a preexisting neurodevelopmental anomaly. However, it remains unknown whether these deficits relate to clinical symptoms and/or conversion to frank psychosis. To address this gap, we examined cross-sectional and longitudinal white matter maturation in the largest imaging population of CHR individuals to date, obtained from the North American Prodrome Longitudinal Study (NAPLS-3). Methods: Multi-shell diffusion magnetic resonance imaging (MRI) data were collected across multiple timepoints (1–6 at ~2 month intervals) in 286 subjects (age range=12–32 years). These were 230 unmedicated CHR subjects, including 11% (n=25) who transitioned to psychosis (CHRconverters), as well as 56 age and sex-matched healthy controls. Raw diffusion signals were harmonized to remove scanner/site-induced effects, yielding a unified imaging dataset. Fractional anisotropy of cellular tissue (FAt) and the volume fraction of extracellular free-water (FW) were assessed in 12 major tracts from the IIT Human Brain Atlas (v.5.0). Linear mixed effects (LME) models were fitted to infer developmental trajectories of FAt and FW across age for CHR-converters, CHR-nonconverters and control groups, while accounting for the repeated measurements on each individual. Results: The rate at which FAt changed with age significantly differed between the three groups across commissural and association tracts (5 in total; p<0.05). In these tracts, FAt increased with age in controls (0.002% change per year) and in CHR-nonconverters, albeit at a slower rate (0.00074% per year). In contrast, FAt declined with age in CHR-converters at a rate that was significantly faster (-3.944% per year) than the rate of increase in the other two groups. By 25 years of age, FAt was significantly lower in both CHR groups compared to controls (p<0.05). With regard to FW, the rate of change significantly differed between CHR-converters and controls across the forceps major and the left inferior longitudinal and fronto‐occipital fasciculi (IFOF; 3 tracts in total; p<0.05). This was due to increased FW with age in the CHR-converters (0.0024% change per year) relative to controls (-0.0002% per year). Consequently, FW was significantly higher in CHR-converters compared to controls by 20 years of age (p<.05). With regard to symptoms, there was a significant impact of IFOF FW on positive symptom severity across CHR subjects, regardless of conversion status (t=2.37, p<0.05). Discussion: Our results revealed that clinical high-risk for psychosis is associated with cellular-specific alterations in white matter, regardless of conversion status. Only converters showed excess extracellular free-water, orbito‐frontal areas. We also demonstrate a direct impact of free-water on positive symptomatology, collectively, suggesting that excess freewater may signal acute psychosis and its onset. This marker may be useful for patient selection for clinical trials and assessment of individuals with prodromal psychosis [ABSTRACT FROM AUTHOR]

Background and Objectives: Exposure to repetitive head impacts (RHI) is linked to the development of chronic traumatic encephalopathy (CTE), which can only be diagnosed at post-mortem. The presence of a cavum septum pellucidum (CSP) is a common finding in post-mortem studies of confirmed CTE and in neuroimaging studies of individuals exposed to RHI. This study examines CSP in living former American football players, investigating its association with RHI exposure, traumatic encephalopathy syndrome (TES) diagnosis, and provisional levels of certainty for CTE pathology., Methods: Data from the DIAGNOSE CTE Research Project were used to compare the presence and ratio of CSP in former American football players (n = 175), consisting of former college (n = 58) and former professional players (n = 117), and asymptomatic unexposed controls without RHI exposure (n = 55). We further evaluated potential associations between CSP measures and cumulative head impact index (CHII) measures (frequency, linear acceleration, and rotational force), a TES diagnosis (yes/no), and a provisional level of certainty for CTE pathology (suggestive, possible, and probable)., Results: Former American football players exhibited a higher CSP presence and ratio than unexposed asymptomatic controls. Among player subgroups, professional players showed a greater CSP ratio than former college players and unexposed asymptomatic controls. Among all football players, CHII rotational forces correlated with an increased CSP ratio. No significant associations were found between CSP measures and diagnosis of TES or provisional levels of certainty for CTE pathology., Discussion: This study confirms previous findings, highlighting a greater prevalence of CSP and a greater CSP ratio in former American football players compared with unexposed asymptomatic controls. In addition, former professional players showed a greater CSP ratio than college players. Moreover, the relationship between estimates of CHII rotational forces and CSP measures suggests that cumulative frequency and strength of rotational forces experienced in football are associated with CSP. However, CSP does not directly correlate with TES diagnosis or provisional levels of certainty for CTE, indicating that it may be a consequence of RHI associated with rotational forces. Further research, especially longitudinal studies, is needed for confirmation and to explore changes over time., Competing Interests: C.H. Adler consulted for Avion, CND Life Sciences, Jazz, and PreCon Health; LJB is Editor-in-Chief of the Journal of Neuro-Ophthalmology and is a paid consultant to Biogen (Cambridge, MA, USA); C. Bernick receives research support from the Ultimate Fighting Championship, Top Rank promotions, Haymon Boxing, Las Vegas Raiders, and Professional Bull Riders. He is a paid consultant for Aurora Concussion Therapy Systems, Inc. (St. Paul, MN); A.P. Lin consulted for Agios, BioMarin, and Moncton MRI. He is a co-founder of BrainSpec, Inc; J.L. Cummings has provided consultation to Acadia, Alkahest, AlphaCognition, AriBio, Avanir, Axsome, Behren Therapeutics, Biogen, Biohaven, Cassava, Cortexyme, Diadem, EIP Pharma, Eisai, GemVax, Genentech, Green Valley, Grifols, Janssen, LSP, Merck, NervGen, Novo Nordisk, Oligomerix, Ono, Otsuka, PRODEO, Prothena, ReMYND, Renew, Resverlogix, Roche, Signant Health, Suven, United Neuroscience, and Unlearn AI pharmaceutical, assessment, and investment companies; E.M. Reiman is a compensated scientific advisor for Alkahest, Alzheon, Aural Analytics, Denali, Green Valley, Retromer Therapeutics, and Vaxxinity and is a cofounder of ALZPath; R.A. Stern is a paid consultant to Biogen (Cambridge, MA, USA) and Lundbeck (Copenhagen, Denmark). He is a member of the Board of Directors of King-Devick Technologies, Inc. (Chicago, IL, USA), and he receives royalties for published neuropsychological tests from Psychological Assessment Resources, Inc. (Lutz, FL, USA). He has been a member of the Medical Science Committee for the National Collegiate Athletic Association Student-Athlete Concussion Injury Litigation; I.K. Koerte receives funding for a collaborative project from Abbott Inc. She receives royalties for book chapters. Her spouse is an employee at Siemens AG and a stockholder of Siemens AG and Siemens Healthineers. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)