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Glucocorticoids and placental 11βHSD2 - A systematic review of human studies and animal models.

CONTEXT: Elevated prenatal glucocorticoid (GC) exposure is linked to adverse offspring outcomes. The placental enzyme 11β-hydroxysteroid-dehydrogenase-type-2 (11βHSD2) protects the fetus by converting maternal derived cortisol to inactive cortisone. Although in vitro studies suggest GC mediated upregulation of 11βHSD2, in vivo evidence remains inconclusive. METHODS: PubMed, Embase, and PsycInfo were searched in October 2024 for human and mammalian animal studies on endogenous or exogenous GCs during pregnancy and associations with placental 11βHSD2 (mRNA, protein, activity, gene methylation). Narrative synthesis was conducted due to heterogeneity precluding meta-analysis. RESULTS: Eighteen studies (eight human, ten animal populations) met inclusion criteria. Exogenous GC exposure was associated with modifications in placental 11βHSD2 expression in animal models, with effects varying by substance, timing, and species. Dexamethasone trended towards increased expression in rodents, whereas betamethasone increased expression in non-human primates but not rodents. Human studies on endogenous GCs showed inconsistent associations with 11βHSD2 changes. In asthmatic pregnancies, moderate inhaled GC-use maintained enzyme activity compared to untreated patients. No convincing sex-specific trend emerged. CONCLUSIONS: GC exposure alters placental 11βHSD2 in a substance- and species-specific way; translational relevance remains limited based on current literature. Future studies should employ technological advances and include GC-sensitive biomarkers to clarify mechanisms of maternal-fetal stress transmission.

Female

Prognostic effect of serum glial fibrillary acidic protein and neurofilament light chain for predicting progression independent of relapse activity in multiple sclerosis: A systematic review.

BACKGROUND: Progression independent of relapse activity (PIRA) is increasingly appreciated as one of the important factors contributing to disability accumulation in MS. sGFAP and sNfL could represent markers reflecting two separate biological processes related to relapse-independent progression in MS. OBJECTIVE: To perform a systematic review of the literature on blood GFAP and/or NfL measured in relation to PIRA or other similar relapse-independent progression endpoints in people with MS. METHODS: PubMed, Scopus, and Web of Science databases were searched from inception to 1 June 2026. The eligible studies were original human studies measuring blood GFAP and/or NfL concentrations in serum, plasma, or any other type of blood-derived material and assessing PIRA, PIRMA, CDP/CDW without relapses, relapse-free EDSS progression, non-inflammatory progression, or comparable relapse-independent disability worsening outcomes. Methodological quality was assessed according to the Newcastle-Ottawa scale and the QUIPS instrument for bias detection in the body of evidence on prognostic factors. Due to heterogeneity of outcomes, biomarker measurements and effect estimates, results were synthesized qualitatively rather than quantitatively. RESULTS: After removing duplicates, 1206 records were screened, followed by full-text review of 120 reports. A total of 18 reports were included. Overall, sGFAP was associated more frequently with PIRA or PIRA-like disability progression, particularly in cohorts with suppressed or limited overt inflammatory activity. Evidence for sNfL was more variable and context-dependent: several studies reported associations with PIRA-like or relapse-independent disability worsening when acute inflammatory activity was absent, suppressed, or analytically separated, whereas other studies reported negative or inconclusive findings. Negative or inconclusive results were reported by several articles, particularly when broad outcomes were evaluated or the study population was small. CONCLUSION: Blood GFAP and NfL give complementary but non-interchangeable information concerning PIRA in MS patients. The existing evidence base does not allow us to perform meta-analysis because of heterogeneity in terms of outcomes, standardization of biomarkers, and treatment context. Further prospective investigations with uniform criteria will be necessary for their use as biomarkers of PIRA in clinical settings.

Humans

Late hiatal hernia after Roux-en-Y gastric bypass: a systematic review.

Obesity is a global public health issue. This condition is linked to gastroesophageal reflux disease (GERD) and hiatal hernia (HH), both of which are exacerbated by increased intra-abdominal pressure. Roux-en-Y gastric bypass (RYGB) is one of the most widely performed techniques for treating obesity and is considered a versatile option suitable for most patients. The development of a symptomatic HH and pouch migration can lead to various symptoms and complications. PubMed, EMBASE, and Cochrane Central were searched for studies with late HH after RYGB. We pooled outcomes for symptom resolution. Secondary outcomes were recurrence rate and operation characteristics (mesh use, cruroplasty, gastropexy, reoperation, length of stay, and operative time). A meta-analysis could not be conducted due to significant heterogeneity in HH. HH following RYGB presents with GERD (39-93.6%), obstructive symptoms (29%-88%), and abdominal pain (28.6%-71%). Diagnostic methods include endoscopy, computed tomography scans, and upper gastrointestinal series. Surgical management varies, with primary cruroplasty being the most common approach, sometimes incorporating mesh or fundoplication. Postoperative symptom resolution rates range from 42.9% to 100%, with HH recurrence occurring in 5%-6.54% of cases. Follow-up durations varied, showing improvement in most patients, though some continued to experience reflux and dysphagia HH contributes to obstructive and reflux symptoms, with contrast-enhanced imaging offering the highest diagnostic accuracy. Bioabsorbable mesh may reduce recurrence, highlighting the need for long-term monitoring.

Humans

Co-location of services: an umbrella review to consider how primary care estates could be better used to support disadvantaged groups.

AIM: To examine how co-located community and health services in primary care could support disadvantaged groups. BACKGROUND: Co-locating services is thought to improve access, collaboration, and patient outcomes. There are thousands of primary care premises across the UK. At a time of stagnating or widening health inequalities, they present an ideal opportunity to support communities, especially in disadvantaged areas. METHOD: We conducted a systematic umbrella review. Articles were retrieved from Ovid MEDLINE and Ovid Embase with supplementary snowball and grey literature searches. Reviews of co-located services supporting disadvantaged groups in primary care between 2010 and February 2024 were included. Quality and risk of bias were assessed using the Joanna Briggs Institute checklist. Two reviewers assessed eligibility, extracted data and assessed quality. Outcomes relating to health, welfare, healthcare utilization, and activity and processes were assessed. Data were narratively synthesized using a convergent integrated approach. FINDINGS: 2626 studies were screened, supplemented by snowball and grey literatures searches. Thirteen reviews were included for synthesis. One review included meta-analysis. Three models of care were identified; legal advice, welfare advice, and complementary health care. Data were synthesized according to themes: access and engagement, quality of care, efficiency, improved health, and improved social factors. We found co-located services can improve access to care, engagement in treatment, and quality of care for disadvantaged groups. Improvements to social determinants of health and mental health and well-being outcomes were reported. Findings were inconsistent when considering the impact of co-location on efficiency. We conclude that co-located services in primary care have the potential to improve identification of people most in need and improve their access to high quality health care and social support. Policy makers and practitioners should maximize the use of primary care estates to support disadvantaged groups and communities.

Humans

Timing of aneurysm repair and clinical outcomes after aneurysmal subarachnoid hemorrhage: a systematic review.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) causes substantial morbidity and mortality, and guidelines recommend aneurysm repair as early as feasible. However, the association between onset-to-treatment time and outcomes remains uncertain. This review synthesized evidence across multiple clinical outcomes and examined whether treatment modality modifies this association. METHODS: Searches were conducted in PubMed/MEDLINE, Scopus, and LILACS for studies comparing clinical outcomes across different onset-to-treatment windows in adults with confirmed aSAH. Findings were synthesized narratively according to the Synthesis Without Meta-analysis (SWiM) guideline. The review was prospectively registered in PROSPERO (CRD420261415084). RESULTS: Twenty reports comprising 11,096 participant records were included, with likely overlap between two reports. Treatment categories ranged from <6&#xa0;h to &#x2265;15&#xa0;days. Earlier securement likely reduced pretreatment rebleeding, particularly when untreated or markedly delayed patients were included, although treated-cohort comparisons were inconsistent. More methodologically informative adjusted analyses showed no reproducible independent association between treatment timing and functional outcome or mortality. No consistent association emerged for vasospasm or related cerebral ischemia, hydrocephalus, or length of stay. Two observational studies modeled time continuously: one found a significant U-shaped mortality association with an estimated nadir at 32.6&#xa0;h, whereas the other showed a similar but non-significant adjusted pattern with an estimated nadir near 12.16&#xa0;h. These findings are highly susceptible to confounding by indication and survivor bias and do not establish benefit from treatment delay. Three studies formally tested modality-timing interaction; one found a significant mortality interaction and two did not. Additional stratified analyses showed no consistent modality-specific pattern. Certainty of evidence for the timing-mortality association was very low because of serious risk of bias, inconsistency, and imprecision. CONCLUSION: Earlier aneurysm securement remains supported for preventing pretreatment rebleeding. The independent association of treatment timing with mortality or functional outcome remains uncertain. The observed mortality patterns are hypothesis-generating and do not define a validated therapeutic window, support intentional treatment delay, or justify changing current guideline recommendations. Prospective multicenter studies using continuous-time modeling and rigorous methods to address confounding and survivor bias are needed.

Humans

Orthoplastic management of open calcaneal fractures: A systematic review of flap selection and complications.

BACKGROUND: Open calcaneal fractures are rare, high-energy injuries involving extensive soft-tissue loss and comminuted bone disruption. Successful management depends on coordinated orthoplastic reconstruction to achieve stable fixation and durable coverage. Multiple flap types have been described, yet comparative outcomes remain poorly defined. METHODS: A systematic review was performed in accordance with PRISMA guidelines (PROSPERO: CRD420251138394). MEDLINE, Embase, Cochrane CENTRAL, and Scopus were searched from January 2000 to July 2025. Studies reporting flap-based reconstruction for open calcaneal fractures in adults were included. Extracted data included flap type, fixation method, follow-up duration, and complications such as infection, necrosis, vascular crises, flap loss, and amputation. RESULTS: Thirteen studies comprising 88 major flap reconstructions were analysed. Overall flap survival was 97.7%, with two failures (both muscle/myocutaneous). Fasciocutaneous flaps showed the lowest complication rates (8.3%) with no reported cases of infection, while muscle/myocutaneous flaps demonstrated cases of infection (20%) and accounted for both flap failures and the only reported amputation. Chimeric flaps were increasingly used in recent series (n&#x202f;=&#x202f;32), achieving reliable survival but higher vascular compromise (6.3%). Osteocutaneous flaps were rare (n&#x202f;=&#x202f;4) and primarily used for defects with bone loss, showing infection in 50% of cases. Meta-analysis was not possible due to heterogeneity and small sample sizes. CONCLUSIONS: Fasciocutaneous flaps provide reliable, low-complication coverage for clean wounds, while muscle flaps remain valuable for contamination or complex cases with extensive tissue loss. Chimeric, and osteocutaneous flaps show promise, but larger, standardised studies are needed to clarify their roles in hindfoot reconstruction.

Humans

Artificial intelligence-derived myocardial fibrosis on cardiac magnetic resonance for prognosis in cardiomyopathy: A systematic review of a sparse evidence base.

BACKGROUND: Myocardial fibrosis on cardiovascular magnetic resonance (CMR), assessed by late gadolinium enhancement (LGE) and parametric mapping, is an established predictor of adverse events in cardiomyopathy. We assessed whether artificial intelligence (AI) quantification of fibrosis adds independent prognostic value. METHODS: We searched six databases, a clinical-trials register, and a preprint server from inception to 13 June 2026. Eligible studies used AI to generate a fibrosis marker in adults with ischemic or nonischemic cardiomyopathy, with covariate-adjusted outcomes over &#x2265;12 months. Risk of bias was assessed using PROBAST, PROBAST+AI, and QUIPS. Fewer than three comparable studies precluded meta-analysis; certainty was rated using GRADE. RESULTS: Of 448 records (381 after de-duplication), 18 full texts were reviewed and two included, one peer-reviewed and one preprint. In an ischemic-cardiomyopathy registry (Ghanbari et al.; n = 216 analytic, 26 events), AI-derived dense LGE scar predicted arrhythmic events (univariable hazard ratio [HR] 2.35, 95% CI 1.33-4.15), and AI-derived but not manual scar improved discrimination beyond guideline criteria (area under the curve 0.63 to 0.68; p = 0.02). In a nonischemic dilated-cardiomyopathy preprint (Kim et al.; n = 347, 119 events), automated extracellular volume &#x2265;30% predicted cardiovascular death or heart-failure hospitalization (adjusted HR 2.00, 95% CI 1.32-3.03). Both were at high risk of bias, with data-derived thresholds and no external validation. CONCLUSIONS: Across only two studies, AI-derived fibrosis was independently associated with adverse cardiovascular events, but its added value over manual quantification remains unproven. Certainty was very low. The evidence base is sparse and not yet ready for clinical use.

Humans

Methods for defining equity-stratifying variables: a systematic review of validation studies.

BACKGROUND AND OBJECTIVE: Disease burden is often disproportionally higher among those who are socially disadvantaged by factors defined in the PROGRESS-Plus framework (ie, Place of residence, Race/ethnicity/culture/language, Occupation, Gender/sex, Religion, Education, Socioeconomic status, and Social capital, with "Plus" covering features like age and disability). The accuracy and applicability of case definitions to identify these variables from administrative and clinical health data are unknown. We conducted a systematic review to explore how equity-stratifying variables, as categorized by the PROGRESS-Plus framework, have been defined and validated in epidemiologic studies using administrative health, population-level, or electronic health record (EHR) data. METHODS: Medline, EMBASE, CINAHL, Web of Science, and Google Scholar were searched from the inception of the databases to 2024 for validation studies of equity-stratifying variables in adults using administrative health datasets, health registries, or EHR data. Titles and abstracts, followed by relevant full-text articles, were screened in duplicate by two reviewers for eligibility. The data sources utilized, algorithms employed, and their associated performance measures were extracted and synthesized from included studies. Given substantial heterogeneity in study design, equity-stratifying variable definition, and performance metrics, meta-analysis was not possible. RESULTS: Of the 9099 unique citations screened, 188 full texts were reviewed and 116 were included in this review. Most studies were published between 2019 and 2024 (n = 64, 55%) and were validation studies of race/ethnicity definitions that used race/ethnicity codes or surname list algorithms (n = 66, 57%). No studies examined religion. Regarding the reported performance measure estimates, the race/ethnicity/culture/language equity-stratifying variables category had the largest variability across sensitivity, positive predictive value (PPV), and Cohen's Kappa. Occupation validation studies had the lowest variation in sensitivity and PPV. CONCLUSION: Despite an increasing number of publications reporting on the validation of equity-stratifying variables relevant to the PROGRESS-Plus framework, performance measures varied widely across studies. The significant heterogeneity in equity-stratifying variable definitions and methods used to validate them support the need for further rigorous validation of equity-stratifying variables in administrative and clinical health data. PLAIN LANGUAGE SUMMARY: Disease burden is often higher in people who experience financial hardships, lower level of education, discrimination due to race/ethnicity, and unstable housing. These social factors can be considered health equity factors and are important for understanding health inequalities. Health researchers often use large datasets, such as hospital or electronic health records (EHRs), to study these health equity factors. However, it is not clear how accurately these data sources capture information about people's social circumstances and how these factors are defined. In this study, we reviewed existing research to understand how health equity factors have been defined across health data sources and how accurate they are at measuring aspects of health equity and social disadvantage. Of the more than 9000 studies we identified, we included 116 that met our criteria for this systematic review. Most included studies focused on identifying race and ethnicity, often using codes or surname-based methods. We found that the accuracy of these methods varied widely across studies, meaning results may not always be reliable or comparable. Overall, our findings show that there are inconsistencies in how social factors are defined and measured in health data. This makes it difficult to fully understand and address health inequalities using routinely collected health data. More work is needed to develop and validate better quality and more consistent methods for capturing these important social factors.

Humans

Robot-assisted bladder diverticulectomy in adults: a systematic review and pooled analysis of perioperative and functional outcomes.

Robot-assisted bladder diverticulectomy (RABD) is used for symptomatic acquired bladder diverticula, but evidence is dispersed across small single-centre series and the only dedicated systematic review dates from 2010. We reviewed contemporary perioperative and functional outcomes of RABD. Following a protocol registered on the Open Science Framework ( https://doi.org/10.17605/OSF.IO/54CFT ), PubMed, Embase, the Cochrane Library, Scopus and Web of Science were searched from inception to 30 August 2026 (initial search June 2026, re-run and broadened for this version), following PRISMA 2020. Eligible studies were original series of five or more adults undergoing robot-assisted bladder diverticulectomy reporting extractable outcomes. Two reviewers independently screened, extracted data and appraised risk of bias with the Joanna Briggs Institute checklist for case series, with third-reviewer adjudication. Binary outcomes were pooled as proportions with Wilson 95% confidence intervals (CI); continuous outcomes were summarised as patient-number-weighted descriptive values, because mixed median/mean reporting and clinical heterogeneity precluded a formal pooled-effect meta-analysis. Twelve studies (146 patients) were included and all outcomes were extracted from the full-text reports. A transperitoneal route was used throughout. There were no conversions to open surgery (0/129; 95% CI 0-2.9%). Major complications (Clavien-Dindo&#x2009;&#x2265;&#x2009;III) occurred in 3.0% (4/135; 95% CI 1.2-7.4%). Patient-number-weighted descriptive values (combining study-level medians and means, and therefore not a pooled mean) were: operative time 163 min, blood loss 99 mL, length of stay 3.6 days and catheter duration 7.7 days. Symptom scores and post-void residual improved in every reporting series, significantly in five. The single non-randomised comparison with open surgery reported fewer major complications after RABD (5% [1/20] vs. 50% [3/6], p&#x2009;=&#x2009;0.007), but the open arm comprised only six patients and this finding should not be regarded as comparative evidence. Across these series, RABD was feasible with low reported short-term morbidity in selected patients: no conversions to open surgery were recorded in the studies reporting conversion status, the major-complication rate was low, and symptom scores and post-void residual improved in every series that measured them. A minority of patients had an incidentally detected intradiverticular tumour; oncological outcomes were not an endpoint of this review. Evidence remains limited by small, heterogeneous, mostly retrospective series, so these findings should be read as descriptive; prospective comparative data are warranted.

Humans

Effectiveness of Internet-Delivered Cognitive Behavioural Therapy (ICBT) in Improving Weight-Loss and Psychosocial Well-Being Among Adults With High BMI: A Systematic Review.

AIM: To examine the effectiveness of Internet-delivered Cognitive Behaviour Therapy (ICBT) in improving psychosocial well-being and promoting weight-loss in adults &#x2265;&#x2009;18&#x2009;years with BMI &#x2265;&#x2009;25&#x2009;kg/m2. BACKGROUND: Global obesity engenders significant physical and psychosocial health consequences. Second-wave ICBT focused on restructuring negative thoughts and behaviours has been explored as a potential intervention for elevated BMI and mental health concerns, but its effectiveness remains to be fully established, making further evaluation essential. METHODS AND DATA SOURCES: Eight databases were searched from inception to January 2025 for randomised controlled trials (RCTs), including participants &#x2265;&#x2009;18&#x2009;years with BMI &#x2265;&#x2009;25&#x2009;kg/m2 and second-wave ICBT evaluating BMI, weight, depression, eating behaviours, and self-esteem. This review followed PRISMA 2020. Study quality was assessed using the Cochrane Risk of Bias (ROB 2) and GRADE. Data were extracted using a modified Cochrane form. Random-effects meta-analysis calculated Standardised Mean Differences (SMD) with 95% confidence intervals, with subgroup analyses exploring heterogeneity. RESULTS: Nine trials with 2278 participants were included. Significant improvements were seen in BMI, weight, and depressive symptoms while self-esteem effects were small and non-significant. Compared with passive controls, ICBT showed greater improvements in BMI and weight, whereas differences versus active control were smaller and inconsistent. Face-to-face CBT demonstrated superior outcomes for depression and self-esteem. Male-tailored interventions showed greater improvements. Shorter programmes yielded larger short-term weight loss, while longer programmes supported more sustained effects. Narrative synthesis indicated improvements in emotional and external eating, with increased mindful and restrictive eating behaviours. CONCLUSION: ICBT improved weight, BMI, and depressive symptoms, with limited evidence for self-esteem. Male-tailored interventions and longer programmes may enhance sustainable outcomes. IMPACT: Future ICBT programs should integrate strategies targeting sustainable weight loss and psychosocial well-being to support long-term outcomes. NO PATIENT OR PUBLIC CONTRIBUTION: Patients or members of the public were not involved, as this study synthesised previously published data. TRIAL REGISTRATION: PROSPERO registration number: CRD42024497961.

Humans

A systematic literature review on low-grade myofibroblastic sarcoma of the trunk.

BACKGROUND: Low-grade myofibroblastic sarcoma (LGMS) is a rare malignant mesenchymal tumor, with primary trunk involvement being particularly uncommon. Due to its rarity, associated diagnostic challenges, and variability in management, a comprehensive evaluation of the available evidence is required. This study aims to systematically review the clinical characteristics, treatment strategies, and outcomes of truncal LGMS. METHODS: A systematic literature search was conducted using PubMed, Web of Science, and Embase for articles published from January 1998 to January 2026. The review included full-text articles involving patients with a pathologically confirmed diagnosis of truncal LGMS. The collected data included patient demographics, tumor features, treatment modalities, recurrence, and follow-up status. RESULTS: Of the 404 studies initially identified, 30 studies involving 59 patients with pathologically confirmed truncal LGMS met the inclusion criteria. Outcome analyses of therapeutic management and clinical course included 45 patients with complete follow-up data, including 42 surgically treated patients and 3 non-surgically managed patients. The final evidence base consisted solely of retrospective studies and case reports. No prospective studies or randomized controlled trials were identified. Consequently, a descriptive statistical analysis was conducted instead of a meta-analysis. CONCLUSION: Current evidence indicates that wide excision with negative margins may be a reasonable primary treatment option for truncal LGMS, with case-based reports showing numerically lower recurrence after wide excision, although the evidence is limited and potentially confounded by multiple factors. Radiotherapy or chemotherapy may be considered only on a highly individualized basis for selected unresectable, recurrent, metastatic, anatomically constrained, or margin-positive cases. Given the very limited sample size and heterogeneous treatment indications across published cases, treatment efficacy cannot be reliably estimated from the available data. Prolonged long-term regular follow-up is recommended for all patients, considering the risk of late recurrence.

Humans

Ageing effects on chemical, physical, mechanical, and morphological properties of clear aligners - a systematic review.

BACKGROUND: Clear aligner (CA) therapy has experienced rapid use over the past two decades to treat orthodontic malocclusions. However, evidence on CA material degradation in the oral environment remains limited and often focuses on single brands or isolated material properties. OBJECTIVES: To investigate CA ageing characteristics across different materials and brands and evaluate the chemical, physical, mechanical, and morphological changes following simulated or intraoral ageing. SEARCH METHODS: Five databases (PubMed, Web of Science, MEDLINE [Ovid], ProQuest, and Scopus) were searched to 18 March 2026, with no restrictions. ELIGIBILITY CRITERIA: Studies assessing CA properties after intraoral use or simulated ageing (thermocycling, cyclic loading, or liquid immersion) were included. DATA COLLECTION AND ANALYSIS: Study selection followed PRISMA 2020. RoB was assessed using QUIN for purely in vitro studies, JBI for cohort in vivo studies, and Cochrane RoB 2 for RCTs. Results were synthesised narratively and organised by property domain, as substantial methodological heterogeneity precluded formal meta-analysis. Where protocols were comparable, a simple pooled weighted mean was calculated and presented graphically. RESULTS: Ninety-five studies were included. RoB was low in eight studies, moderate in sixty-two, and high in twenty-five. Chemical composition remained largely stable during ageing, though some brands showed trace elemental release. Physical, mechanical, and morphological properties showed material-dependent deterioration. Pooled discolouration was greatest with coffee (weighted mean &#x394;E&#x2009;=&#x2009;70.9), versus tea (&#x394;E&#x2009;=&#x2009;18.4) and red wine (&#x394;E&#x2009;=&#x2009;11.5), with Invisalign&#xae; consistently exceeding the clinically perceptible threshold. Force decay of 40-90% typically occurred within 48&#xa0;h. Thermoplastic polyurethane (TPU)-based and directly printed aligners (DPAs) generally showed greater susceptibility than polyethylene terephthalate glycol-modified (PETG)-based aligners, though findings on hardness, roughness, and stiffness were inconsistent. CONCLUSIONS: CA materials undergo clinically relevant degradation during use, particularly in TPU-based and DPAs aligners. Clinicians may need to prioritise material-specific protocols, reinforce dietary and cleaning instructions, and consider force decay when determining aligner replacement intervals. PROSPERO number: CRD420251110248.

Humans

Pharmacological and non-pharmacological modulation of striatal dopamine release: a meta-analysis of [11C]raclopride PET studies.

The dopaminergic system has long been a central focus of functional neuroimaging. Positron emission tomography (PET) with the D2/D3 receptor radioligand [11C]raclopride remains the most widely used method for indirectly quantifying striatal dopamine release in vivo. However, no previous meta-analysis has studied the relative magnitude and regional distribution of dopamine release across different interventions or cognitive interventions overall. To address this gap, in this meta-analysis of 92 [11C]raclopride PET studies (n&#x2009;=&#x2009;1640), we compared the magnitude and regional distribution of dopamine release induced by amphetamine, methylphenidate, ketamine, alcohol, and cognitive challenges with and without reward. Amphetamine induced approximately four-fold greater dopamine release than cognitive challenges (10.9 vs. 2.7%, p&#x2009;<&#x2009;0.001), and approximately twice that of alcohol (4.8%, p&#x2009;<&#x2009;0.001), with effects comparable to methylphenidate (11.5%) and slightly greater than ketamine (9.8%). Psychostimulant-induced increase in synaptic dopamine was greater in putamen and ventral striatum than in caudate, whereas alcohol preferentially engaged ventral striatum. Dopamine release did not differ between rewarded and non-rewarded cognitive tasks in the ventral striatum (p&#x2009;>&#x2009;0.14) or overall striatum (p&#x2009;>&#x2009;0.10). Methylphenidate-induced increases in synaptic dopamine appeared to attenuate with advancing age, whereas cognitive challenges were associated with greater dopamine release in older individuals. These findings demonstrate that individual pharmacological and cognitive interventions differ markedly in both magnitude and regional pattern of dopamine release. They also suggest that [&#xb9;&#xb9;C]raclopride PET may have limited sensitivity for distinguishing reward-related from non-reward-related dopamine release. These findings have implications for the design and interpretation of future neuroimaging studies of dopaminergic function in health and disease.

Journal Article