CB1 Receptor Silencing Attenuates Ketamine-Induced Hyperlocomotion Without Compromising Its Antidepressant-Like Effects

Introduction: The antidepressant properties of ketamine have been extensively demonstrated in experimental and clinical settings. However, the psychotomimetic side effects still limit its wider use as an antidepressant. It was recently observed that endocannabinoids are inolved in ketamine induced reward properties. As an increase in endocannabinoid signaling induces antidepressant effects, this study aimed to investigate the involvement of cannabinoid type 1 receptors (CB1R) in the antidepressant and psychostimulant effects induced by ketamine. Methods: We tested the effects of genetic and pharmacological inhibition of CB1R in the hyperlocomotion and antidepressant-like properties of ketamine. The effects of ketamine (10-20 mg/kg) were assessed in the open-field and the forced swim tests (FSTs) in CB1R knockout (KO) and wild-type (WT) mice (male and female), and mice pre-treated with rimonabant (CB1R antagonist, 3-10 mg/kg). Results: We found that the motor hyperactivity elicited by ketamine was impaired in CB1R male and female KO mice. A similar effect was observed upon pharmacological blockade of CB1R in WT mice. However, genetic CB1R deletion did not modify the antidepressant effect of ketamine in male mice submitted to the FST. Surprisingly, pharmacological blockade of CB1R induced an antidepressant-like effect in both male and female mice, which was not further potentiated by ketamine. Conclusions: Our results support the hypothesis that CB1R mediate the psychostimulant side effects induced by ketamine, but not its antidepressant properties.

A75 COLONOSCOPY COLORECTAL CANCER DETECTION - HOW DOES IT VARY BY INDICATION, SETTING AND PATIENT DEMOGRAPHIC?

Background

Because of limited access to gastrointestinal (GI) endoscopy during the COVID-19 pandemic, there is a need to prioritize procedures to avoid negative health impacts from delays. Ontario Health (OH) has provided guidance to facilities to prioritize colonoscopies in people with an abnormal fecal immunochemical test (FIT) result, based on the high likelihood to detect invasive colorectal cancer (CRC) and recommends FIT for screening people at average risk of CRC and those with prior low-risk adenoma.

Purpose

To measure the invasive CRC detection rate (CDR) of colonoscopies performed in Ontario by indication, setting, age, and sex over a 31-month period before and during the COVID-19 pandemic.

Method

We calculated the CDRs among outpatients ages 18 and over who had colonoscopies performed in a hospital or private clinic setting from June 2019 to December 2021. We identified hospital colonoscopies from OH’s GI Endoscopy Data Submission Portal and clinic colonoscopies from Ontario Health Insurance Plan (OHIP) data (OHIP code E749A). Invasive CRC was identified from the Ontario Cancer Registry (OCR) as: ICD-O-3 codes C18.0, C18.2-C18.9, C19.9, C20.9, a morphology indicative of CRC, microscopically confirmed and with a pathology report. CRCs were included if diagnosed 7 days before and up to 183 days after colonoscopy. Colonoscopy volumes and CDRs were stratified by age and sex (all volumes), and, for hospital colonoscopies, by indication.

Result(s)

During the study period, 984,109 colonoscopies were performed (638,900 in hospitals; 345,209 in clinics). Patients who had their colonoscopies in clinics were younger than those who had them in hospitals (Table 1). In both settings, colonoscopies were evenly distributed by sex. Overall, 12,021 CRCs were detected (CDR: 1.22%); 9,451 CRCs in hospitals (CDR: 1.48%), and 2,570 CRCs in clinics (CDR: 0.74%). CDRs at any age were lower in clinics as compared to hospitals. In hospitals, CDRs by colonoscopy indication were: 5.16% for FIT+, 1.93% in symptomatic patients, 0.52% in surveillance, 0.70% in average-risk screening, and 0.35% in screening due to family history. FIT+ colonoscopies accounted for the smallest proportion of colonoscopies (6.2%) but the 2^nd largest proportion of CRCs detected (Figure 1). Hospital-based CDR increased during the period of observation from 1.23% pre-pandemic (June-December 2019) to 1.55% during the pandemic (January-December 2021). Clinic CDR was 0.71% pre-pandemic and 0.75% during the pandemic.

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Conclusion(s)

In Ontario, colonoscopy yield (CDR) is highest in FIT+ patients; just over one in 20 colonoscopies will yield a diagnosis of CRC. In contrast, primary screening and surveillance indications have very low CRC yields. The overall yield of colonoscopies in clinics, for all age groups, is lower than in hospital setting. There was a slight increase in CDR during the pandemic compared to before the pandemic, in both settings.

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Ontario Health - Cancer Care Ontario

Disclosure of Interest

None Declared

B-77 Buddha's Brain: A Systematic Review of Mindfulness-Based Interventions in the Rehabilitation Context

Objective

The current study was intended to provide a rigorous systematic review of the evidence to date regarding the efficacy of mindfulness-based interventions (MBIs) in persons with neurologic illness/injury, a form of treatment that may be particularly well suited to the rehabilitation context due to its holistic approach.

Data Selection

The search was conducted in accordance with the PRISMA guidelines for systematic reviews. We included any controlled trials of MBIs conducted in a neurological population, employing the specific practice of mindfulness meditation. A search protocol was created and executed by three of the authors to promote reliability and obtain the initial list of abstracts (n = 35). Two authors independently reviewed and extracted data from the final 30 full-text articles.

Data Synthesis

A majority (83%) of studies used randomized designs, with the most frequent diagnoses of interest being aging/ neurodegenerative diseases (n = 10), followed by MS (n = 6), TBI (n = 5), and ADHD (n = 5). Most trials that assessed psychological variables found significant benefits (n = 24), including variables such as fatigue, self-reported cognitive function, and specific neurological symptoms. Comparatively fewer studies looked at cognitive and/or neural outcomes (n = 18) such as attention or processing speed, although most did tend to find significant benefits in these outcomes as well.

Conclusions

Results of this review indicate promising evidence for the application of MBIs in the rehabilitation context. Further work is needed to determine whether targeting MBIs to certain symptom clusters as opposed to diagnoses would enhance observed clinical benefit.

B-79 Trauma through the Neuropsychologist's Eyes: A Systematic Review of Standardized Test Results after Trauma

Objective

Approximately 90% of adults in the United States have been exposed to trauma (Kilpatrick et al. 2013). Among clients seen for neuropsychological services, trauma may be an etiological or co-occurring factor, especially with traumatic brain injury. Understanding neuropsychological impact is essential to trauma-informed assessment, diagnosis, and rehabilitation. Prior reviews were limited to between-group statistical differences rather than clinically significant results. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses, this review evaluated studies of standardized neuropsychological test scores among adults with trauma histories and psychopathology.

Data Selection

Terms for “neuropsychology” and “trauma” were searched within peer-reviewed empirical studies from PsycINFO, MedLine with Full Text, and Published International Literature on Traumatic Stress from 1/2013-8/2018. 2350 initial records were ultimately reduced to 21 articles, after removing duplicates and ineligible articles (e.g., no standardized neuropsychological tests or scores, baseline treatment assessments, studies where age groups were not stratified, non-clinical samples). Extracted data included demographic, neuropsychological, and clinical characteristics, and potential study biases.

Data Synthesis

Studies assessed combat trauma (n = 8), developmental trauma (n = 2), intimate partner violence and sexual assault (n = 2), accidental trauma (n = 2), refugee trauma (n = 1), and unspecified trauma (n = 6) in the context of various psychiatric conditions. Performance across neuropsychological domains ranged from low to high average, with one borderline verbal memory score.

Conclusions

Lack of clinically observable neuropsychological impairment suggests cognitive challenges are state-based, driven by intra-individual variability and the psychophysiological traumatic stress response. Client-centered rehabilitation emphasizing self-regulation is recommended. Future research can expand on assessment comprehensiveness and ecological validity.