In contemporary neuroimaging studies, it has been observed that patients with major depressive disorder (MDD) exhibit aberrant spontaneous neural activity, commonly quantified through the amplitude of low-frequency fluctuations (ALFF). However, the substantial individual heterogeneity among patients poses a challenge to reaching a unified conclusion.

To address this variability, our study adopts a novel framework to parse individualized ALFF abnormalities. We hypothesize that individualized ALFF abnormalities can be portrayed as a unique linear combination of shared differential factors. Our study involved two large multi-center datasets, comprising 2424 patients with MDD and 2183 healthy controls. In patients, individualized ALFF abnormalities were derived through normative modeling and further deconstructed into differential factors using non-negative matrix factorization.

Two positive and two negative factors were identified. These factors were closely linked to clinical characteristics and explained group-level ALFF abnormalities in the two datasets. Moreover, these factors exhibited distinct associations with the distribution of neurotransmitter receptors/transporters, transcriptional profiles of inflammation-related genes, and connectome-informed epicenters, underscoring their neurobiological relevance. Additionally, factor compositions facilitated the identification of four distinct depressive subtypes, each characterized by unique abnormal ALFF patterns and clinical features. Importantly, these findings were successfully replicated in another dataset with different acquisition equipment, protocols, preprocessing strategies, and medication statuses, validating their robustness and generalizability.

This research identifies shared differential factors underlying individual spontaneous neural activity abnormalities in MDD and contributes novel insights into the heterogeneity of spontaneous neural activity abnormalities in MDD.

In the absence of treatments to halt or reverse symptoms of Alzheimer's disease, early detection may extend the window for meaningful treatment, advanced planning, and coping. Positron emission tomography (PET) scans for amyloid and tau are validated biomarkers of AD, yet results are rarely disclosed to participants due to concerns about negative impacts. While prior studies suggest limited anxiety, depression, or suicidality following biomarker disclosure, no study to date has examined broader psychological impacts of PET amyloid/tau disclosure to symptomatic individuals. Therefore, we explored post-disclosure changes in future time perspective (perceptions of limited time or possibilities left in the future), self-efficacy for managing symptoms, and perceived stigma as a function of result received.

Forty-three older adults (age = 72.0±6.2 years; education = 16.5±2.6; 88.4% White Non-Hispanic; 48.8% female) participated in the study, of whom 62.8% were diagnosed with mild cognitive impairment (MCI) and the remainder with Dementia of the Alzheimer's type. All participants underwent pre-disclosure biomarker education and decisional capacity assessment, followed by baseline measures. Participants demonstration decisional capacity completed an interactive disclosure session during which they received dichotomous results of their research positron emission tomography (PET) scans for amyloid and tau (elevated versus not elevated for each biomarker). Findings were discussed in relation to presence/absence of Alzheimer's disease, the etiology of their cognitive difficulties, and risk for conversion or further decline. At baseline, immediately following disclosure, and at 1-week follow-up, participants completed several questionnaires: the Future Time Perspective (FTP) scale, a measure of how much the participant sees time as limited, the Self Efficacy for Managing Chronic Disease scale (SECD), and the Stigma Scale for Chronic Illness (SSCI-8), all of which were modified to apply to Alzheimer's disease and associated experiences.

The main effects of time (F=1.10, p=.334, A?p2=.026), biomarker status (F(1)=3.10, p=.086, Ajp2=.070), and the time by biomarker status interaction (F=0.39, p=.661, Ajp2=.009) on FTP score was not significant. Though neither time (F=0.07, p=.933, A?p2=.002) nor the time by biomarker status interaction (F=2.16, p=.122, Ajp2=.050) effect on SECD was significant, being biomarker positive (A+T-/A+T+) was associated with lower self-efficacy (F(1)=5.641, p=.022, Ajp2=.121). Neither main effect for time (F=0.15, p=.853, Ajp2=.004) or biomarker status (F(1)=0.35, p=.558, A?p2=.009) on SSCI-8 was significant. The time by biomarker status interaction was significant (f=4.27, p=.018, =.096), such that biomarker negative participants experience a transient increase in perceived stigma directly after disclosure that resolves one week later, and biomarker negative participants experience the opposite pattern.

Findings suggest that individuals who receive biomarker positive results may feel less competent to manage their symptoms compared to those who are biomarker negative, emphasizing the need for post-disclosure interventions targeting self-efficacy. The effect of disclosure on perceptions of time being limited and on perceived stigma were minimal, even when those results indicate evidence of Alzheimer's disease and risk for clinical progression. These results further support the safety of biomarker disclosure procedures. Future studies should provide longer-term assessment of psychological, behavioral, and clinical outcomes following Alzheimer's disease biomarker disclosure.

Intraindividual variability (IIV) is defined as fluctuations in an individual’s cognitive performance over time1. IIV has been identified as a marker of neurobiological disturbance making it a useful method for detecting changes in cognition among cognitively healthy individuals as well as those with prodromal syndromes2. IIV on laboratory-based computerized tasks has been linked with cognitive decline and conversion to mild cognitive impairment (MCI) and/or dementia (Haynes et al., 2017). Associations between IIV and AD risk factors including apolipoprotein (APOE) ε4 carrier status, neurodegeneration seen on brain imaging, and amyloid (Aß) Positron emission tomography (PET) scan status have also been observed1. Recent studies have demonstrated that evaluating IIV on smartphone-based digital cognitive assessments is feasible, has the capacity to differentiate between cognitively normal (CN) and MCI individuals, and may reduce barriers to cognitive assessment3. This study sought to evaluate whether such differences could be detected in CN participants with and without elevated AD risk.

Participants (n=57) were cognitively normal older adults who previously received an Aß PET scan through the Butler Hospital Memory and Aging Program. The sample consisted of primarily non-Hispanic (n=49, 86.0%), White (n=52, 91.2%), college-educated (M=16.65 years), females (n=39, 68.4%). The average age of the sample was 68 years old. Approximately 42% of the sample (n=24) received a positive PET scan result. Participants completed brief cognitive assessments (i.e., 3-4 minutes) three times per day for eight days (i.e., 24 sessions) using the Mobile Monitoring of Cognitive Change (M2C2) application, a mobile app-based cognitive testing platform developed as part of the National Institute of Aging’s Mobile Toolbox initiative (Sliwinski et al., 2018). Participants completed visual working memory, processing speed, and episodic memory tasks on the M2C2 platform. Intraindividual standard deviations (ISDs) across trials were computed for each person at each time point (Hultsch et al., 2000). Higher ISD values indicate more variability in performance. Linear mixed effects models were utilized to examine whether differences in IIV existed based on PET scan status while controlling for age, sex at birth, and years of education.

n interaction between PET status and time was observed on the processing speed task such that Aß- individuals were less variable over the eight assessment days compared to Aß + individuals (B= -5.79, SE=2.67, p=.04). No main or interaction effects were observed on the visual working memory task or episodic memory task.

Our finding that Aß- individuals demonstrate less variability over time on a measure of processing speed is consistent with prior work. No associations were found between IIV in other cognitive domains and PET status. As noted by Allaire and Marsiske (2005), IIV is not a consistent phenomenon across different cognitive domains. Therefore, identifying which tests are the most sensitive to early change is crucial. Additional studies in larger, more diverse samples are needed prior to widespread clinical use for early detection of AD.

There is a need to identify scalable cognitive paradigms that are sensitive enough to relate to Alzheimer's disease biomarkers (amyloid and tau) in the preclinical stage. Here, we determine whether initial performance and practice effects on the memory-focused Computerized Cognitive Composite (C3) relate to demographic variables, amyloid status [abnormal (A+), normal (A-)], and regional tau in clinically unimpaired (CU) older adults.

We examined pre-randomization data from CU older adults screened for the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) study. We focused on participants who completed the C3 (n=3287), most of whom completed an alternate version of the C3 again approximately 51 days later (n=4141), as well as a subset of preclinical AD participants (i.e., A+ CU) who completed the C3 and tau PET imaging with [18]F-flortaucipir (initial C3: n=354; repeat C3: n=343). C3 initial performance and practice effects were examined in relation to amyloid status (A+, A-) and continuous regional tau burden.

Initial C3 performance was associated with amyloid status [B(SE) = -0.075 (0.021), p < 0.001] across all participants, as well as tau burden in the medial temporal lobe (MTL) [B (SE) = -0.728 (0.220), p = 0.001], inferior temporal (IT) cortex [B (SE) = -0.782 (0.264), p = 0.003], and inferior parietal (IP) cortex [B (SE) = -0.721 (0.281), p = 0.011] amongst preclinical AD individuals. Short-term practice effects were also associated with reduced tau burden in MTL [B (SE) = -0.471 (0.202), p = 0.020], IT [B (SE) = -0.640 (0.240), p = 0.008], and IP [B( SE) = - 0.584 (0.255), p = 0.023] amongst preclinical AD participants, but were not associated with amyloid status [B (SE) = -0.018 (0.020), p = 0.348]. Critically, these effects with tau were only detected when baseline performance was accounted for presumably due to opposing influence from both practice effects and regression to the mean effects.

This is the first study to show that performance on a brief cognitive battery administered in a multisite context is associated with both amyloid and tau among CU older adults. These findings suggest that computerized assessments may be a cost-effective and scalable approach for early detection efforts. Further, diminished practice effects on memory-based measures are associated with elevated tau burden in preclinical AD, suggesting that high-frequency cognitive testing collected over a short follow-up period may provide additional insights regarding early disease processes than single assessments.

There are many potential benefits of early identification of those with Alzheimer’s disease (AD), including more opportunity for early intervention to slow AD progression (e.g., treatment, lifestyle changes, etc.) and to plan for the future. Positron emission tomography (PET) scans for abnormal amyloid and tau are commonly conducted in research settings. Despite strong interest in learning AD biomarker results, participants rarely receive their research data, in part due to concern about the possibility of undue distress based on results. We aimed to explore both positive and negative emotional reactions following PET biomarker disclosure as a function of result received.

Forty-three older adults (age = 72.0±6.21 years, education = 16.5±2.62 years, 49% Female, 88% White Non-Hispanic) completed PET amyloid and tau testing and disclosure. Sixty-three percent were diagnosed with mild cognitive impairment (MCI) while the remainder of participants were diagnosed with Dementia Alzheimer’s type (DAT). Participants completed pre-disclosure biomarker education and a decisional capacity assessment followed by baseline measures. Participants then completed a disclosure session where they received personal PET amyloid and tau results on an elevated vs. not elevated scale for each ligand. Results were discussed in relation to presence/absence of Alzheimer’s disease, how the result relates to their cognitive difficulties, and risk of developing Dementia-Alzheimer’s Type. At baseline (pre-disclosure), immediately post-disclosure, and 1-week post-disclosure, participants completed the Beck Anxiety Inventory (BAI), The Geriatric Depression Scale - 15 Item (GDS-15), Impact of Neuroimaging in AD (INI-AD) Scale, and the Positive and Negative Affective Scale - Short Form (PANAS-SF). All questionnaires were modified to apply to Alzheimer’s disease and related experiences.

Of the 43 participants who participated in disclosure, 74% received biomarker positive results (either A+T- or A+T+); all others were biomarker negative. We conducted a series of mixed analysis of variance (ANOVA) tests to determine the effect of disclosure and biomarker status for each of the outcomes of interest. Neither the effect of time nor the time by biomarker status interaction was significant for any of the outcomes (all p>.05). The main effect of biomarker status was significant for BAI (F(1)=5.12, p=.031, n,p2=.146) and INI-AD Distress (F(1)=12.70, p=.001, np2=.241) and Positive (F(1)=34.57, p<.001, np2=.464) subscale scores with A+T-/A+T+ participants reporting higher negative affect than those who were A-/T-; however, even among biomarker positive individuals, scores did not exceed clinical thresholds. GDS-15, PANAS-Negative and Positive Subscale scores did not differ significantly by biomarker status (all p>.05) and no significant adverse events occurred following disclosure. Additionally, no participants cited regret about receiving their results.

While disclosure of biomarker positivity may result in mild increases in acute anxiety or distress, or fewer positive emotions, it does not result in clinically significant emotional reactions and was not associated with regret. Overall, findings are consistent with literature indicating safety of biomarker disclosure procedures for symptomatic individuals. Future research should follow participants over longer periods to evaluate the impacts of biomarker disclosure.

Alzheimer’s disease (AD) pathophysiology, including β-amyloid (Aβ), can be appreciated with molecular PET imaging. Among older adults, the distribution of Aβ standard uptake value ratios (SUVR) is typically bimodal and a diagnostic cut is applied to define those who are amyloid ‘positive’ and ‘negative’. However, it is unclear whether the dynamic range of SUVRs in amyloid positive and negative individuals is meaningful and associated with cognition. Previous work by Insel and colleagues (2020) used screening data from the Anti-Amyloid Treatment in Asymptomatic Alzheimer’s (A4) trial to demonstrate subtle associations between a cortical summary SUVR and cognition, particularly on the Free and Cued Selective Reminding Test (FCSRT). We followed up this study to determine the extent to which regional SUVR is associated with performance on the FCSRT in amyloid positive and negative participants screened for participation in the A4 study.

We accessed regional Aβ SUVR, including anterior cingulate, posterior cingulate, parietal, precuneus, temporal, and medial/orbital frontal regions, along with FCSRT15 and demographic data from 4492 A4 participants at screening. Participants were coded as amyloid positive (n=1329; 30%) or amyloid negative (n=3169; 70%) based on a summary SUVR of greater than or equal to 1.15. We used separate general linear models to examine the association of total or regional SUVR, amyloid positivity status, and the interaction of SUVR and amyloid status with FCSRT scores. We compared model fits across regions with the Akaike Information Criterion (AIC). We ran post hoc correlational analyses examining the relationship between SUVR and FCSRT scores stratified by amyloid status in the case of significant interactions. Results were similar with and without demographic adjustment.

There was a significant interaction of summary and all regional SUVR with FCSRT scores in addition to main effects of amyloid positivity. In all models, there were small negative associations between SUVR and memory in amyloid positive individuals. For amyloid negative individuals, there was a significant and very small negative association between SUVR and FCSRT scores only in the parietal lobes and precuneus regions. Model fits were generally similar across the different analyses.

In this sample of individuals screened for a secondary prevention trial of AD, there were consistent associations between Aβ SUVR in all regions and memory for those considered amyloid positive. However, for individuals considered amyloid negative, there were only very small associations between SUVR and memory in parietal and precuneus regions. We conclude that the dynamic range of amyloid may be relevant among those with diagnostic evidence of amyloidosis, but that subtle Aβ accumulation in posterior regions may relate to declining memory in “subthreshold” states.

Reported childhood adversity (CA) is associated with development of depression in adulthood and predicts a more severe course of illness. Although elevated serotonin 1A receptor (5-HT1AR) binding potential, especially in the raphe nuclei, has been shown to be a trait associated with major depression, we did not replicate this finding in an independent sample using the partial agonist positron emission tomography tracer [11C]CUMI-101. Evidence suggests that CA can induce long-lasting changes in expression of 5-HT1AR, and thus, a history of CA may explain the disparate findings.

Following up on our initial report, 28 unmedicated participants in a current depressive episode (bipolar n = 16, unipolar n = 12) and 19 non-depressed healthy volunteers (HVs) underwent [11C]CUMI-101 imaging to quantify 5-HT1AR binding potential. Participants in a depressive episode were stratified into mild/moderate and severe CA groups via the Childhood Trauma Questionnaire. We hypothesized higher hippocampal and raphe nuclei 5-HT1AR with severe CA compared with mild/moderate CA and HVs.

There was a group-by-region effect (p = 0.011) when considering HV, depressive episode mild/moderate CA, and depressive episode severe CA groups, driven by significantly higher hippocampal 5-HT1AR binding potential in participants in a depressive episode with severe CA relative to HVs (p = 0.019). Contrary to our hypothesis, no significant binding potential differences were detected in the raphe nuclei (p-values > 0.05).

With replication in larger samples, elevated hippocampal 5-HT1AR binding potential may serve as a promising biomarker through which to investigate the neurobiological link between CA and depression.

Long-term physiological dysfunction in coronary/systemic vasculature may persist in individuals with Kawasaki disease even in the absence of coronary artery abnormalities. We perform a systematic review and meta-analyses of studies assessing long-term vascular function in Kawasaki disease.

PubMed, Embase, and Web of Science databases were searched for relevant literature published till May 2021. Patients with Kawasaki disease were included as cases and healthy age/sex-matched individuals as controls. Newcastle Ottawa Scale was used to assess the study quality. Outcome measures were differences in markers of vascular function 1 year after diagnosis of Kawasaki disease. Data were analysed using Review Manager software. Comprehensive meta-analysis software was used for meta-regression. To assess the certainty of evidence, GRADE Profiler software was utilised.

Of 2280 citations, 49 case-control studies (comprising 2714 cases and 2118 controls) were included for data synthesis. Decreased flow-mediated dilatation [3.83, 95%CI 0.94–6.72] and increased pulse-wave velocity [39.34 cm/sec, 95%CI 20.86–57.83], arterial stiffness [0.35, 95%CI 0.11–0.59], and common carotid artery intima-media thickness were noted in patients with Kawasaki disease. No significant difference was observed for nitroglycerine-mediated dilatation and endothelial peripheral artery tonometry (endo-PAT). Significant inter-study heterogeneity was observed for flow-mediated dilatation, arterial stiffness, carotid artery intima-media thickness, and endo-PAT. The GRADE evidence was of ‘very low quality’ for all outcome measures except ‘moderate quality’ for pulse-wave velocity.

Evidence suggests the presence of long-term endothelial dysfunction in patients with Kawasaki disease even in the absence of coronary artery abnormalities. Avoidance of development of other cardiovascular risk factors seems prudent in patients with Kawasaki disease.

A large proportion of Alzheimer’s disease (AD) patients have coexisting subcortical vascular dementia (SVaD), a condition referred to as mixed dementia (MixD). Brain imaging features of MixD presumably include those of cerebrovascular disease and AD pathology, but are difficult to characterize due to their heterogeneity.

To perform an exploratory analysis of conventional and non-conventional structural magnetic resonance imaging (MRI) abnormalities in MixD and to compare them to those observed in AD and SVaD.

We conducted a cross-sectional, region-of-interest-based analysis of 1) hyperintense white-matter signal abnormalities (WMSA) on T2-FLAIR and hypointense WMSA on T1-weighted MRI; 2) diffusion tensor imaging; 3) quantitative susceptibility mapping; and 4) effective transverse relaxation rate (R2*) in N = 17 participants (AD:5, SVaD:5, MixD:7). General linear model was used to explore group differences in these brain imaging measures.

Model findings suggested imaging characteristics specific to our MixD group, including 1) higher burden of WMSAs on T1-weighted MRI (versus both AD and SVaD); 2) frontal lobar preponderance of WMSAs on both T2-FLAIR and T1-weighted MRI; 3) higher fractional anisotropy values within normal-appear white-matter tissues (versus SVaD, but not AD); and 4) lower R2* values within the T2-FLAIR WMSA areas (versus both AD and SVaD).

These findings suggest a preliminary picture of the location and type of brain imaging characteristics associated with MixD. Future imaging studies may employ region-specific hypotheses to distinguish MixD more rigorously from AD or SVaD.

Autism spectrum disorder (ASD) remains a behaviourally defined condition. Its molecular basis is unknown; however, its prevalence has been increasing significantly. There have been several abnormalities in neurotransmitter systems reported in ASD. In our review, we described studies involving positron emission tomography (PET) and single-photon emission computed tomography (SPECT) that can provide useful and corroborative data.

We conducted a literature review by comprehensive database searching on EMBASE, Scopus, PubMed, and PsychINFO looking for articles published since January 2009. Thirty-one studies were carefully selected – 22 PET studies and 9 SPECT studies – and reviewed by 2 independent researchers. References of the articles were also cross-checked.

Results of the studies, which mainly involve small groups of participants, are frequently inconclusive and often controversial due to the nature of ASD and its wide spectrum. Studies are conducted under different conditions and with poor control for confounding factors which creates difficulties in comparing the data.

There is ongoing need to improve methodology of the studies involving molecular imaging in ASD. Lack of consistent findings causes difficulties in evaluation, diagnosis, and treatment of the condition.

We present the first results of the MINDVIEW project. An innovative imaging system for the human brain examination, allowing simultaneous acquisition of PET/MRI images, has been designed and constructed. It consists of a high sensitivity and high resolution PET scanner integrated in a novel, head-dedicated, radio frequency coil for a 3T MRI scanner. Preliminary measurements from the PET scanner show sensitivity 3 times higher than state-of-the-art PET systems that will allow safe repeated studies on the same patient. The achieved spatial resolution, close to 1 mm, will enable differentiation of relevant brain structures for schizophrenia. A cost-effective and simple method of radiopharmaceutical production from 11C-carbon monoxide and a mini-clean room has been demonstrated. It has been shown that 11C-raclopride has higher binding potential in a new VAAT null mutant mouse model of schizophrenia compared to wild type control animals. A significant reduction in TSPO binding has been found in gray matter in a small sample of drug-naïve, first episode psychosis patients, suggesting a reduced number or an altered function of immune cells in brain at early stage schizophrenia.