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Introduction

Digital Rectal Exam (DRE) is a medical procedure where a lubricated gloved finger is inserted into the rectum to check for abnormalities, enlargements, lumps, tenderness, and hardness in the prostate, rectum, and pelvis.¹ Since the DRE only reaches the back wall of the prostate glands, the anomaly of the front and middle parts of the prostate gland cannot be ascertained. As these areas of the prostate are not accessible from outside the body, the utility of a single DRE has been questioned in screening for prostate cancer, as it is considered less reliable than Prostate Specific Antigen (PSA) blood test.^1–3 A meta-analysis of 8 studies with 85,798 participants showed that the positive predictive value (PPV) of DRE and PSA are approximately the same: 0.21 (95% CI = 0.13–0.33) and 0.22 (95% CI = 0.15–0.30), respectively, with no additional benefit observed when combining DRE and PSA (PPV = 0.22, 95% CI = 0.13–0.26).⁴ This meta-analysis concluded that the cancer detection rate was lower for DRE than PSA.

Since early-stage prostate cancer is typically asymptomatic, both DRE and PSA tests are used for screening. The existing guidelines for DRE screening were developed in conjunction with PSA testing through randomized trials to enhance biopsy decision-making. For instance, the US Preventive Services Task Force (USPSTF) recommends biennial DRE in conjunction with PSA testing for men with hypogonadism and for those with PSA less than 2.5 ng/mL.^5,6 The National Comprehensive Cancer Network (NCCN) recommends a prostate biopsy if the PSA value exceeds 3.0 ng/mL or if the DRE result is very suspicious.⁷ The American Urological Association (AUA) advises that clinicians should consider performing DRE on patients with PSA levels of 2 ng/mL or higher to assess the risk of clinically significant cancer.⁸ However, the USPSTF does not recommend DRE as a standalone screening for prostate cancer despite cases where DRE has found prostate cancers in men with normal PSA levels.⁵ In contrast to the USPSTF, the German Statutory Early Detection Program has recommended stand-alone DRE for prostate cancer screening on 45+ years old male since 1971.⁹ DRE is also a part of clinical assessment tools such as European Randomized Study of Screening for Prostate Cancer.¹⁰ However, a multicentric randomized trial enrolling more than 46,000 men aged 45 years old to test for risk-adapted PSA screening for prostate cancer found that the stand-alone DRE screening for prostate cancer is poor because it also does not improve the detection of PSA-screen-detected prostate cancer and may not be recommended as a screening test for younger men.⁹ According to this randomized trial, out of 57 men with a suspicious DRE at the age of 45 years old, only 3 had actual prostate cancers. The calculated DRE detection rate was 0.05% (3/6537) compared with the 4x higher detection by 0.21% PSA screening (48/23301).⁹ The current study utilized trend analysis to detect abnormal DRE patterns, providing insights that may decrease the chance of false positives.

A meta-analysis of seven studies with 9,241 patients estimated the pooled sensitivity, specificity, and PPV of DRE to be 51%, 59%, and 41%, respectively.¹¹ This meta-analysis recommends against routine DRE screening in the primary care setting. However, the majority of primary care physicians in Canada are routinely using DRE in the primary care setting and 38% of 955 physicians believe that DRE provides a survival benefit.^12,13 In the United States, despite the impact of USPSTF guidelines on clinical practice, DRE is performed routinely by 84% of primary care physicians, particularly among men aged 50 and older.¹⁴ Until now, DRE remains to be an acceptable procedure as a standard of care in urology clinics.¹⁵

We presented numerous studies that have shown stand-alone DRE has poor performance in detecting prostate cancer in primary care settings. We hypothesize that long-term follow-up such as serial DRE testing in which repeated suspicious results might improve DRE detection rate.^5,16 In this study, we utilized data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial¹⁷ to evaluate whether long-term DRE screening offers crucial information for early detection of prostate cancer. This study examines 10-year trends of suspicious DRE findings among PLCO participants who were diagnosed or not diagnosed with prostate cancer. We theorize that the likelihood of suspicious DRE would change over time depending on prostate cancer status.

Materials and Methods

Study Population

A secondary analysis was conducted in the intervention arm from the PLCO Cancer Screening Trial.¹⁷ For this prospective study, participants aged 55–74 years were recruited from the US general population and randomly assigned to the intervention arm or the control arm at 10 clinical centers between November 1993 and July 2001.¹⁸ There was a nearly even split with 38,338 in the control arm that offered the standard care to participants and 38,340 in the intervention arm that underwent prostate cancer screening tests (total = 76,678). The PLCO trial was conducted in accordance with the Declaration of Helsinki. All participants were given informed consent, and the research was approved by the institutional review boards of all the 10 participating centers and the US National Cancer Institute (NCI). This study received approval (PLCO-1141) from the NCI to access deidentified data sets. PLCO trial design and methodology have been published previously.¹⁹

Study Inclusion and Exclusion

The PLCO Cancer Screening Trial includes participants who meet the eligibility criteria, and they receive either usual care as the control (N=38,338) or annual screening (N=38,340).¹⁹ The usual care arm was excluded from the analysis due to the lack of DRE screening¹⁹ and excluded missing race (N=914). Due to the small sample sizes of some ethnic groups, we restricted the study to black and white and excluded all other races. Therefore, our final analytic file contains 34,756 male participants.

Measurements

DRE Measurement

Participants in the screening arm were screened annually using DRE at four visits. Thus, there were four DRE exams (T0–T3) before and at diagnosis among the 34,756 participants who completed at least one of the screenings. To maintain quality assurance, a sample of men were selected for a second DRE by an independent examiner during the same screening session. In cases of discordant results, personalized screening outcomes and diagnostic paths were assigned for each patient.¹⁹ Participants with a suspicious DRE were advised to seek diagnostic follow-up care from their primary care providers.¹⁸ The DRE findings ranged from 1 (negative), 2 (abnormal, suspicious), 3 (abnormal, non-suspicious), 4 (inadequate screen), 8 (not done, expected), and 9 (not done, not expected). The DRE findings for this study were classified into: 0 (normal), 1 (abnormal non-suspicious), and 2 (abnormal suspicious). DRE codes 4, 8, and 9 were treated as missing. We analyzed the DRE findings over a 10-year period before and at the prostate cancer diagnosis (positive/negative). The 10-year follow-up adequately demonstrates changes in DRE findings, as men who underwent DRE within 10 years of diagnosis experienced a significant reduction of prostate cancer-specific mortality.²⁰ We defined the time at DRE result as the years before a positive or negative prostate cancer diagnosis (+ or -), where “0” represents the DRE result at the time of diagnosis (+ or -), and “-10” represents the DRE result “10” years prior to the diagnosis (+ or -). This calculation was based on days from randomization until the DRE test at each visit and days from randomization to a positive (+) or negative (-) prostate cancer.

Covariates

We included baseline data, such as participant age at randomization, body mass index (BMI) defined as weight (kg) divided by height (m²), education level (college degree: no, yes), race (Black, White), marital status (married: no, yes), frequent urination (defined as urinating three or more times a night: no, yes), immediate family history of prostate cancer (no, yes), and enlarged prostate or benign prostatic hypertrophy (BPH) (no, yes). The PLCO screening trial confirmed prostate cancer diagnoses via medical record abstraction such as a self-report of prostate cancer, death certificate indicating prostate cancer, and relative information to the screening center of the participant’s cancer. The assessment includes the question “does the participant have confirmed primary invasive prostate cancer diagnosed during the trial?”: 0 = “no confirmed prostate cancer” and 1 = “confirmed prostate cancer”.

Statistical Analyses

All data analyses were executed in SAS version 9.4 (SAS Institute Inc, Cary NC, United States). Numerical variables (age at randomization and baseline BMI) were presented as mean ± standard deviation (SD) and non-numerical variables (eg, race and education) were presented as count and percentage (Table 1). Proportions of normal, abnormal non-suspicious DRE, and abnormal suspicious DRE were compared across the sample characteristics using the Chi-square test (Tables 2–5). ANOVA test was used to compare age at randomization and baseline BMI across DRE findings (Tables 2–5). We modeled DRE results over a 10-year follow-up as binary outcomes: abnormal non-suspicious DRE vs normal DRE and abnormal suspicious DRE vs normal DRE. The trend in log odds ratio of abnormal DRE findings was modeled using repeated binary logistic regression via generalized estimating equation (GEE) with the exchangeable regression structure (LOGOR = EXCH). We examined the interaction effect, defined as the combination of follow-up year to diagnosis and prostate cancer status (+ or -) on the likelihood of having an abnormal non-suspicious DRE and an abnormal suspicious DRE, using normal DRE as the reference category. The model adjusted for age, education, marital status, baseline BMI, frequent urinating, family history, and BPH (Table 6). The results were presented in terms of adjusted odds ratio (aOR) and confidence intervals (CIs). CIs inclusive of 1.0 were considered non-significant association, while those without 1 were considered significant association. P-value (P) of less than or equal to 0.05 was considered statistically significant.

Table 1 Sample Characteristics (N = 34,756 Participants)

Table 2 Assessing the Association Between DRE Findings and Sample Characteristics at the Baseline Visit (T0) (N= 34,756 Participants)

Table 3 Assessing the Association Between DRE Findings and Sample Characteristics at the First Visit (T1) (N= 34,756 Participants)

Table 4 Assessing the Association Between DRE Findings and Sample Characteristics at the second Visit (T2) (N= 34,756 Participants)

Table 5 Assessing the Association Between DRE Findings and Sample Characteristics at the Third Visit (T3) (N= 34,756 Participants)

Table 6 GEE Analysis of Adjusted Odds Ratio of Abnormal DRE as Compared to Normal DRE

Results

Table 1 describes the characteristics of a subsample from the PLCO intervention arm (N=34,756). Of these, 12.3% (4280/34756) had prostate cancer with significantly higher estimates in Black men than in White men (15.1% vs 12.2%, P < 0.001). At the end of the follow-up, the percentage of abnormal suspicious DRE was significantly increased from 6.5% at 10 years prior to diagnosis to 27.2% at diagnosis.

The frequency distribution of normal, abnormal non-suspicious, and abnormal suspicious DRE by the sample characteristics at the baseline visit (T0), visit 1 (T1), visit 2 (T2), and visit 3 (T3) are displayed in Tables 2–5, respectively. In this subgroup analysis, we observed significant association between DRE findings and race, education, and BPH at all four visits. For instance, the percentage of abnormal DRE was lower among Black participants than White participants at all four visits. Age at randomization and baseline BMI were significantly different across DRE findings at all four visits. Specifically, age was positively associated with abnormal DRE findings, while baseline BMI was inversely associated with abnormal DRE findings.

Table 6 presents the results of the GEE analysis of the changes in DRE findings across time (follow-up years to diagnosis) by prostate cancer status. The interaction term (follow-up year to diagnosis × prostate cancer status) was statistically significant, indicating that the likelihood of abnormal DRE findings changes significantly over time between prostate cancer and non-prostate cancer participants. Each year closer to diagnosis, the prostate cancer participants were expected to increase the odds of abnormal non-suspicious DRE by 5.2% (aOR=1.052, 95% CI: 1.033–1.072) and abnormal suspicious DRE by 23.0% (aOR=1.230, 95% CI: 1.193–1.268). The probability of abnormal suspicious DRE increases sharply over time in participants with prostate cancer (Figure 1), while the probability of abnormal non-suspicious DRE increases gradually over time in participants with prostate cancer (Figure 2). There is no change in DRE overtime in participants who did not have prostate cancer.

Figure 1 Predicted probability of an abnormal suspicious DRE by follow-up year to diagnosis and prostate cancer status. The probability of having an abnormal suspicious DRE goes up with prostate cancer vs no prostate cancer. Changes in trend observed 8 years before a positive or negative prostate cancer result.

Figure 2 Predicted probability of an abnormal non-suspicious DRE by follow-up year to diagnosis and prostate cancer status.

Older age is associated with higher odds of abnormal DRE, where the odds of abnormal non-suspicious DRE tend to increase by 1.0% for every year increase in age (aOR=1.010, 95% CI: 1.006–1.014) and the odds of abnormal suspicious DRE tend to increase by 4.8% for every year increase in age (aOR=1.048, 95% CI: 1.040–1.055) (Table 6). The odds of abnormal non-suspicious DRE (aOR=0.803, 95% CI: 0.724–0.892) and abnormal suspicious DRE (aOR=0.735, 95% CI: 0.611–0.883) were significantly lower in Black participants compared to White participants. PLCO participants with a college degree had 8.5% lower odds of abnormal non-suspicious DRE (aOR=0.915, 95% CI: 0.874–0.958) and 17.6% lower odds of abnormal suspicious DRE (aOR=0.824, 95% CI: 0.761–0.893) when compared with PLCO participants without a college degree. Participants with higher BMI had lower odds of abnormal DRE, where the odds of abnormal non-suspicious DRE tend to decrease by 1.2% for every kg/m² increase in BMI (aOR=0.988, 95% CI: 0.983–0.994) and the odds of abnormal suspicious DRE tend to decrease by 2.4% for every kg/m² increase in BMI (aOR=0.976, 95% CI: 0.967–0.986). BPH associated with increased odds of abnormal non-suspicious DRE by 57.9% (aOR=1.571, 95% CI: 1.491–1.672) and increased odds of abnormal suspicious DRE by 68.9% (aOR=1.689, 95% CI: 1.541–1.852). Frequent urination and immediate family history of prostate cancer did not affect the odds risk of having abnormal DRE findings (Table 6).

Discussion

This study utilized secondary analysis of follow-up data on 34,756 men from the PLCO Screening Trial to explore changes in the likelihood of abnormal suspicious DRE by investigating the interaction term follow-up year to diagnosis × prostate cancer status. The overall crude prevalence of abnormal suspicious DRE increased over time from 6.5% at 10 years prior to diagnosis to 27.2% at diagnosis. Our GEE model provides evidence to support the research hypothesis by identifying an increasing trend in the likelihood of abnormal suspicious DRE (Figure 1) and abnormal non-suspicious DRE (Figure 2) among men with prostate cancer compared to men without prostate cancer.

We propose that there is still utility in performing DREs consistent with USPTF and AUA as we addressed an important gap in developing a model for long-term follow-up of DRE screening to reduce potential harms associated with a single DRE test.^5,6 Unlike studies that considered DRE as a one-time screening,⁹ our study endorses the usage of long-term follow-up of DRE in primary care settings. A one-time DRE screening is not an effective approach as it misses true positive cases. For instance, Krilaviciute et al reported low detection for prostate cancer of 0.05%, while our study detection rate increases over time: 0.64% at 10 years prior to diagnosis, 6.32% at 5 years prior to diagnosis, 12.60% at 2 years prior to diagnosis, and 43.4% at diagnosis. The positive predictive value of abnormal suspicious DRE was 4.74% at 10 years prior to diagnosis, 36.82% at 5 years prior to diagnosis, 60.63% at 2 years prior to diagnosis, and 90.48% at diagnosis. This is similar to a previous study that reported a high chance of developing prostate cancer in men with suspicious DRE tests at the initial screening, second screening, and third screening.²¹ This suggests that the long-term follow-up of DRE screening is an important and a reliable approach in detecting prostate cancer.

Our study identified several other key factors influencing the likelihood of abnormal suspicious DRE. Black men had significantly lower likelihood of abnormal DRE than White men. The reasons for this difference are not fully understood, but it might be explained by the psychological fear regarding DRE impacting the screening practices and the likelihood of being screened across different race groups as Black men undergo DRE less often and have higher DRE screening fears than White men.^1,22 The DRE screenings rate was much lower for Black men as compared to White men due to the lack of recruitment of Black men.²³

Our findings reveal a low BMI value is an indicator of abnormal DRE findings as we found an inverse correlation between baseline BMI and abnormal DRE. Studies suggest that obese men were less likely to have abnormal DRE findings²⁴ and less likely to have abnormal prostate cancer.²⁵ DRE in obese men presents unique considerations due to the increased tissue in the pelvic area. This may require skilled examiners to physically evaluate the prostate gland for presence of any abnormalities or loss of anatomic landmarks. Therefore, careful DREs in obese patients are vital to ensure effective DRE screening.

Our study showed that men with BPH were associated with greater odds of abnormal DRE than men without BPH. This finding has not been extensively explored, but a study found that abnormal DRE was an independent factor of incidental prostate cancer following BPH surgery.²⁶ We suggest that BPH nodules can mimic nodules caused by prostate cancer on DRE, which has also been shown on prostate MRIs. The current study suggests that older men were more likely to have abnormal DRE findings. Age significantly correlated with prostate cancer.²⁵ Older age may affect the structure of the prostate and can be interpreted as abnormal, which may contribute to false positive results.

Notwithstanding, our study comes with limitations secondary to the inherent nature of retrospective analysis. The study findings may not be generalizable to the African American population due to the greater representations of one race over another may have affected our results²³ as there are more white participants than black participants in the PLCO trial. Unlike the DRE, which has multiple assessments (T0–T3), the prostate cancer status was determined according to one assessment via medical record abstraction such as a self-report of prostate cancer, death certificates indicating prostate cancer, and relative informing the screening center of the participant’s prostate cancer status. Inadequate DRE screening and not completed exams were treated as missing. Consequently, the authors were unable to use GEE analysis to assess the trends of prostate cancer changes within a period of 10 years prior to diagnosis.

The current study, however, has several strengths 1) the PLCO trial is a population-based study and serial DRE testing might represent the study populations, 2) the definition of DRE classification was clearly defined and reproducible to limit interpretation errors amongst clinicians performing DREs, 3) we show the importance of serial DREs overtime in raising the clinical suspicion of prostate cancer as well as its status as an important, feasible, and cost-effective adjunct to serum PSA screening in prostate cancer, and 4) our analysis has been adjusted for age at randomization, BMI, education level, race, marital status, frequent urination, immediate family history, and BPH.

Conclusion

Our results suggest that incorporating serial DRE findings into screening strategies may reduce false positives and improve early detection of clinically significant prostate cancer. This study demonstrates a rising probability of abnormal DRE findings in men with prostate cancer, whereas no temporal change was observed in men without prostate cancer. Long-term follow-up DRE findings can help identify the changes in the prostate gland due to aging to reduce the false positives associated with the PSA test.

Data Sharing Statement

Requests to access the PLCO datasets should be directed to the National Cancer Institute (NCI) Cancer Data Access System (CDAS): https://cdas.cancer.gov/plco/.

Ethics Statement

The PLCO study was approved by the Institutional Review Boards of participating centers and the NCI. The study participants provided written informed consent. Ethical approval was not required. The authors analyzed secondary data from the Prostate, Lung, Colorectal, and Ovarian cancer screening trial.

Acknowledgments

We acknowledge the study participants for their contributions to making this study possible. The authors thank the National Cancer Institute for providing access to data.

The contents of this publication are the sole responsibility of the author(s) and do not necessarily reflect the views, opinions or policies of Uniformed Services University of the Health Sciences (USUHS), The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., the Department of Defense (DoD), the Departments of the Army, Navy, or Air Force. Mention of trade names, commercial products, or organizations does not imply endorsement by the US Government.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Funding

There is no funding to report.

Disclosure

The authors declare no commercial or financial relationships that could be constructed as a potential conflict of interest for this work.

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A new study of young adults has strongly linked better sleep quality with better mental wellbeing, with fruit and vegetable consumption and physical activity also strongly associated with psychological wellbeing. Perhaps surprisingly, the findings also suggest that boosting fruit and vegetable intake could potentially help mitigate the effects on wellbeing of a poor night’s sleep. Dr. Jack Cooper, previously from the University of Otago, New Zealand, and colleagues present these findings in the open-access journal PLOS One on August 27, 2025.

Prior research has linked better health behaviors-actions that people can adjust in their lives-to better physical health. Evidence also suggests that health behaviors may be linked to mental wellbeing. However, research on this topic has been limited. For example, studies have typically focused only on mental illness, a separate measure from positive psychological wellbeing, and they typically neglect to consider how different health behaviors might interact to affect wellbeing.

To address these and other gaps, Cooper and colleagues analyzed relationships between three health behaviors-sleep quality, eating fruits and vegetables, and physical activity-and psychological wellbeing in adults aged 17 to 25. They used data from three studies: a survey study of 1,032 adults in New Zealand, the U.K., and the U.S.; a 13-day study of 818 New Zealand adults who were asked to keep a daily diary; and an 8-day diary study of 236 New Zealand adults who also wore Fitbits tracking physical activity.

Across all three studies, better sleep quality was most strongly associated with better mental wellbeing, with fruit and vegetable consumption coming in second. Both behaviors showed benefits even when comparing between different days for the same person – so eating more fruit and vegetables one day was associated with a real-time wellbeing boost. Physical activity – whether measured by FitBits or diaries, which aligned – was also linked to better wellbeing, but mostly when comparing between days for an individual rather than when comparing across individuals.

Links between each of the three behaviors and wellbeing appeared to be independent and additive – which might mean that the more of them you do, the bigger the wellbeing benefit. The only exception: above-average intake of fruits and vegetables appeared to mitigate the effects of a poor night’s sleep, and a good night’s sleep appeared to protect against lower fruit and vegetable intake.

This study used samples of young adults from three countries-the U.K., U.S., and New Zealand-and samples sizes were relatively homogeneous. Future research could address some of these limitations by including participants from additional countries and increasing the sample size to improve generalizability. Although this study could not prove a causative link between these behaviors and mental wellbeing, the authors hope that their findings could inform efforts to improve psychological wellbeing of young adults.

Young adults don’t have to reach some objective benchmark of healthiness to see wellbeing improvement. Sleeping a little better, eating a little healthier, or exercising even for 10 minutes longer than you normally do was associated with improvements to how you feel that day.”

Dr. Jack Cooper, Lead Author

Senior author Professor Tamlin Conner, of the University of Otago Psychology Department, adds: “Understanding what lifestyle factors support wellbeing can help young adults not just ‘get by’ but thrive during this critical life stage.”

“Of these healthy habits, sleep quality stood out as the strongest and most consistent predictor of next-day wellbeing, but eating fruit and vegetables and being active also helped boost wellbeing”.

“This age group faces unique pressures – such as leaving home, financial stress, educational pressures and social stressors – that can lower happiness. Understanding what lifestyle factors support wellbeing can help young adults not just ‘get by’ but thrive during this critical life stage.

During childhood and adolescence, our brains undergo rapid changes. Studying these changes in juvenile mice has long been challenging because scientists lacked a way to repeatedly image the same animal’s neural pathways as they grow.

Now, researchers at Stanford have developed a revolutionary technique that allows them to do that. By applying a simple solution to a juvenile mouse’s scalp, the team can make the skin transparent to all visible light. This new method creates new opportunities for research on the developing brain that could improve our understanding of neurodevelopmental disorders and lead to new treatment therapies.

‘A literal window’ into brain development

“This opens a literal window to peek into the brain’s development,” said Guosong Hong, an assistant professor of materials science and engineering and senior author on the paper. “Not only can we image the structures of these neurons, but we can also image the neural activity over time in an animal model. In the future, this approach could enable us to look at how these circuits form during the development of an animal.”

The technique is both non-invasive and reversible, meaning scientists can return to the same animal over days and weeks to monitor how its neural circuits evolve. The research, published in PNAS, could advance our understanding of neurodevelopmental disorders and inform new interventions.  

Harnessing fundamental laws for new discoveries

Under normal conditions, light scatters when it hits skin. This scattering occurs whenever light waves encounter interfaces between materials with different optical properties, such as lipids, proteins and other molecules within tissue. The effect is similar to trying to see through sunlit fog, blurring what is underneath.

“From a physics perspective, we’re basically a bag of water with biomaterials,” said Mark Brongersma, the Stephen Harris Professor and professor of materials science and engineering and co-author on the paper. “And the mismatch in their optical properties is why we can’t see through the skin or scalp.”

To overcome this, the team needed to make the water and biomaterials in the skin more similar in their optical properties. This was achieved by raising the refractive index of the water – the degree to which it bends light – to match that of the surrounding biomaterials. By mixing a compound called ampyrone into water and rubbing it on the mouse’s scalp, the researchers successfully turned the skin transparent. Ampyrone absorbs mostly ultraviolet light, allowing scientists to see inside the mouse with the full visible spectrum.

“The fact that such fundamental optics laws can be applied and work in a biological system is just amazing to me,” Brongersma said. “It wasn’t clear whether the physics and the chemistry and the biology would all line up to make this happen.”

Advancing neural imaging

This new method builds on the team’s earlier work, in which they discovered a compound that rendered skin transparent to red light, allowing internal imaging without incisions. Ampyrone goes further, permitting imaging with the full visible spectrum. This makes it possible to observe the colours of green and yellow fluorescent proteins – which are commonly used to mark neural activity.

Because young mice have very thin skulls, fluorescence can be detected until the animals are about four weeks old – the developmental equivalent of a human teenager or early adult. Using this approach, the researchers repeatedly imaged the neurons of sedated juvenile mice and even monitored neural activity in awake mice responding to a puff of air on their whiskers.

This new method provides a non-invasive way to observe brain development in living juvenile mice, offering insights into how neural circuits form and function. By enabling repeated imaging over time, the technique opens new opportunities for studying neurodevelopmental disorders and testing potential interventions. Looking ahead, researchers hope to refine the method and expand its use, ultimately improving our understanding of human brain development and allowing for the production of new treatments for neurological conditions.

Background and objectives

Inflammatory bowel disease (IBD) is a chronic condition with significant health implications worldwide. In Nigeria, data on its prevalence and characteristics are limited, highlighting the need for comprehensive studies to better understand its epidemiology and clinical features in the region. This study aimed to assess the clinical presentation, endoscopic findings, and management challenges of IBD among patients undergoing colonoscopy in Nigeria.

Methods

Over five years (2019–2024), a multicenter, cross-sectional survey was conducted involving clinicians across Nigeria’s six geopolitical zones. It included a retrospective review of records from 18 centers. Data collection was conducted in two phases via Google Forms, focusing on care practices and detailed case information, including demographics, clinical features, histology, and treatment. Data analysis used descriptive statistics and tests for associations, with significance set at p < 0.05.

Results

A total of 459 suspected IBD cases (9.7%) were identified among over 4,700 colonoscopies, with histological confirmation in 208 cases (4.4%), indicating the prevalence of IBD in the Nigerian patient population. The most common subtype was ulcerative colitis (53.9%), followed by Crohn’s disease (21.0%) and indeterminate colitis (25.0%). Regional variations were observed, with higher diagnosis rates in some zones (North-West: 14.9%; South-East: 1.4%). The predominant clinical feature was rectal bleeding. Endoscopic findings frequently showed pan-colitis (62%), with significant regional differences (p < 0.001), and management mainly involved medications such as acetylsalicylic acid derivatives (60.0%), with surgical options rarely employed (0.6%). Challenges included high medication costs and limited availability, which affected nearly half of the patients (49.4%; 46.2%).

Conclusions

The findings of this multicenter survey illuminate the pressing issues surrounding IBD in Nigeria, drawing attention to its prevalence, complex clinical presentations, and significant management challenges. The data reveal critical similarities and differences compared to findings in West Africa, other regions of Africa, Europe, Asia, and the Americas. The lower prevalence in Nigeria and other African studies reflects unique genetic and environmental factors influencing IBD development. Demographic trends indicate a younger population affected by IBD in Nigeria, consistent with regional observations. However, disparities in clinical presentations, treatment modalities, and barriers to care highlight broader challenges within the Nigerian healthcare system that warrant urgent attention.

The use and potency of cannabis is increasing worldwide, and dependence and cannabis-induced psychosis are also greatly increasing as a result, especially in North America. Two new research papers, both using data from Cannabis & Me — the largest survey of its kind — have identified key risk factors associated with the more severe forms of paranoia in cannabis users.

The first study, published on August 26 in the BMJ Mental Health, explored the relationship between why people first started using cannabis, and how this affected their subsequent use.

3389 former and current cannabis users aged 18 and over responded to a survey examining their reasons for first and continued use, their weekly consumption of cannabis in THC units, and their mental health.

Researchers established several key findings. Respondents who first started using cannabis to self-medicate an illness, including physical pain, anxiety, depression, or because they were experiencing minor psychotic symptoms, all demonstrated higher paranoia scores.

This was in contrast to those respondents who tried cannabis for fun or curiosity, or with their friends, who reported the lowest average paranoia and anxiety scores.

Dr Edoardo Spinazzola, a Research Assistant at King’s IoPPN and the study’s first author said, “Our study provides vital evidence on how the reason someone first starts using cannabis can dramatically impact their long-term health.

“This research suggests that using cannabis as a mean to self-medicate physical or mental discomfort can have a negative impact on the levels of paranoia, anxiety, and depression. Most of these subgroups had average scores of depression and anxiety which were above the threshold for referral to counseling.”

Respondents were also asked to provide data on the frequency and strength of the cannabis they were using so that researchers could track their average weekly consumption of Tetrahydrocannabinol (THC) — the principle psychoactive component of cannabis.

The researchers found that the average respondent consumed 206 units of THC a week. This might equate to roughly 10-17 ‘joints’ per week, if the user was consuming an expected 20 per cent THC content that is standard for the most common types of cannabis available in London.

However, respondents who started using cannabis to help with their anxiety, depression, or in cases where they started due to others in their household who were already using cannabis, reported on average 248, 254.7, and 286.9 average weekly THC units respectively.

Professor Tom Freeman, Director of the Addiction and Mental Health Group at the University of Bath and one of the study’s authors said, “A key finding of our study is that people who first used cannabis to manage anxiety or depression, or because a family member was using it, showed higher levels of cannabis use overall.

“In future, standard THC units could be used in a similar way to alcohol units — for example, to help people to track their cannabis consumption and better manage its effects on their health.”

In a separate study, published in Psychological Medicine, researchers explored the relationship between childhood trauma, paranoia and cannabis use.

Researchers used the same data set from the Cannabis & Me survey, with just over half of respondents (52 per cent) reporting experience of some form of trauma.

Analysis established that respondents who had been exposed to trauma as children reported higher average levels of paranoia compared to those who hadn’t, with physical and emotional abuse emerging as the strongest predictors.

Researchers also explored the relationship between childhood trauma and weekly THC consumption. Respondents who reported experience of sexual abuse had a markedly higher weekly intake of THC, closely followed by those who reported experiencing emotional and physical abuse.

Finally, the researchers confirmed that the strong association between childhood trauma and paranoia is further exacerbated by cannabis use, but is affected by the different types of trauma experienced. Respondents who said they had experienced emotional abuse or household discord1 were strongly associated with increased THC consumption and paranoia scores. Respondents reporting bullying, physical abuse, sexual abuse, physical neglect and emotional neglect on the other hand did not show the same effects.

Dr Giulia Trotta, a Consultant Psychiatrist and Researcher at King’s IoPPN and the study’s first author said, “This comprehensive study is the first to explore the interplay between childhood trauma, paranoia, and cannabis use among cannabis users from the general population.

“We have not only established a clear association between trauma and future paranoia, but also that cannabis use can further exacerbate the effects of this, depending on what form the trauma takes.

“Our findings will have clear implications for clinical practice as they highlight the importance of early screening for trauma exposure in individuals presenting with paranoia.”

Professor Marta Di Forti, Professor of Drug use, Genetics and Psychosis at King’s IoPPN, Clinical Lead at the South London and Maudsley NHS Foundation Trust’s Cannabis Clinic for Patients with Psychosis, and the senior author on both studies said, “There is extensive national and internation debate about the legality and safety of cannabis use.

“My experience in clinic tells me that there are groups of people who start to use cannabis as a means of coping with physical and emotional pain. My research has confirmed that this is not without significant further risk to their health and wellbeing, and policy makers across the world should be mindful of the impact that legalisation , without adequate public education and health support, could have on both the individual, as well as on healthcare systems more broadly.”

Cannabis & Me was possible thanks to funding from the Medical Research Council (MRC).