The heritability of blood-based biomarkers related to risk of Alzheimer's disease in a population-based sample of early old-age men

INTRODUCTION

Despite their increased application, the heritability of Alzheimer's disease (AD)-related blood-based biomarkers remains unexplored.

METHODS

Plasma amyloid beta 40 (Aβ40), Aβ42, the Aβ42/40 ratio, total tau (t-tau), and neurofilament light (NfL) data came from 1035 men 60 to 73 years of age (μ = 67.0, SD = 2.6). Twin models were used to calculate heritability and the genetic and environmental correlations between them.

RESULTS

Additive genetics explained 44% to 52% of Aβ42, Aβ40, t-tau, and NfL. The Aβ42/40 ratio was not heritable. Aβ40 and Aβ42 were genetically near identical (rg  = 0.94). Both Aβ40 and Aβ42 were genetically correlated with NfL (rg  = 0.35 to 0.38), but genetically unrelated to t-tau.

DISCUSSION

Except for Aβ42/40, plasma biomarkers are heritable. Aβ40 and Aβ42 share mostly the same genetic influences, whereas genetic influences on plasma t-tau and NfL are largely unique in early old-age men. The absence of genetic associations between the Aβs and t-tau is not consistent with the amyloid cascade hypothesis.

A double-blind, randomized, placebo-controlled study of the safety and effects of CBN with and without CBD on sleep quality

The present study sought to determine the effects of cannabinol (CBN) alone and in combination with cannabidiol (CBD) on sleep quality. This was a double-blind, randomized, placebo-controlled study conducted between May and November 2022. Participants were randomized to receive either (a) placebo, (b) 20 mg CBN, (c) 20 mg CBN + 10 mg CBD, (d) 20 mg CBN + 20 mg CBD, or (e) 20 mg CBN + 100 mg CBD for seven consecutive nights. Participants were 18-55 years of age who self-rated sleep quality as "very poor" or "poor." The primary endpoint was sleep quality, while secondary endpoints included sleep onset latency, number of awakenings, wake after sleep onset (WASO), overall sleep disturbance, and daytime fatigue. In a modified intent-to-treat analyses (N = 293), compared to placebo, 20 mg CBN demonstrated a nonsignificant but potentially meaningful effect on sleep quality (OR [95% CI] = 2.26 [0.93, 5.52], p = .082) and significantly reduced number of awakenings (95% CI [-0.96, -0.05], p = .025) and overall sleep disturbance (95% CI [-2.59, -0.14], p = .023). There was no difference from placebo among any group for sleep onset latency, WASO, or daytime fatigue (all p > .05). Individuals receiving 20 mg CBN demonstrated reduced nighttime awakenings and overall sleep disturbance relative to placebo, with no impact on daytime fatigue. The addition of CBD did not positively augment CBN treatment effects. No differences were observed for latency to sleep onset or WASO. Findings suggest 20 mg of CBN taken nightly may be helpful for improving overall sleep disturbance, including the number of times one wakes up throughout the night, without impacting daytime fatigue. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A Two-Phase, Dose-Ranging, Placebo-Controlled Study of the Safety and Preliminary Test of Acute Effects of Oral Δ8-Tetrahydrocannabivarin in Healthy Participants

Introduction: Tetrahydrocannabivarin (THCV) is an understudied cannabinoid that appears to have effects that vary as a function of dose. No human study has evaluated the safety and nature of effects in a wide range of THCV doses. Methods: This was a two-phase, dose-ranging, placebo-controlled trial of the Δ8 isomer of oral THCV in healthy adults. Phase 1 utilized an unblinded, single-ascending dose design (n=3). Phase 2 used a double-blind, randomized, within-participant crossover design (n=18). Participants received single acute doses of placebo and 12.5, 25, 50, 100, and 200 mg of THCV. Safety measures and subjective and cognitive effects were assessed predose and up to 8 h postdose. Results: Most adverse events (AEs; 55/60) were mild. Euphoric mood was the most common AE. The 12.5, 25, and 200 mg doses produced significantly lower minimum times to complete the digit vigilance test (ps=0.01). The 25 mg dose showed elevations on mean ratings of "energetic" at 1-, 2-, and 4-h postdose, but the maximum postdose rating for this dose did not achieve statistical significance relative to placebo ([95% confidence interval]=3.2 [-0.5 to 6.9], p=0.116). The 100 and 200 mg doses showed elevations on ratings of "feel a drug effect" and "like the drug effect." Almost all urine drug screens (78/79) at 8 h postdose in the active THCV conditions tested positive for tetrahydrocannabinol (THC). Conclusion: All THCV doses displayed a favorable safety profile. Several THCV doses showed a preliminary signal for improved sustained attention, but the effect was not dose dependent. Though mild and not associated with impairment, THC-like effects were observed at higher THCV doses. Oral THCV-containing products could lead to positive urine drug screens for THC. ClinicalTrials.gov ID: NCT05210634.

Oral Cannabidiol Treatment in Two Postmenopausal Women with Osteopenia: A Case Series

Introduction: Cannabidiol (CBD), a nonintoxicating cannabinoid, may be involved in bone remodeling, but human studies are limited. In this case series, we explored the effects of oral CBD administration on bone turnover. Materials and Methods: Two postmenopausal women with osteopenia (T-score=-1 to -2.5) were randomized to receive 100 or 300 mg CBD daily (oral, bis in die [twice per day]) for 12 weeks. Serum markers of bone resorption (carboxyl-terminal collagen crosslinks [CTx]) and bone formation (procollagen type 1 N-terminal propeptide [P1NP], bone-specific alkaline phosphatase [BSAP], and osteocalcin [OC]); safety measures; plasma concentrations of CBD and metabolites; sleep disturbance; symptoms of depression, anxiety, and stress; and quality of life, were assessed. Results: CBD was well tolerated, with no clinically significant change in vital signs, hematology, chemistry, or urinalysis, and no adverse events reported. Reductions (% change vs. baseline) in CTx (-8.5%, -28.1%), P1NP (-9.9%, -39.5%), BSAP (-12.7%, -74.8%), and OC (-16.0%, -6.7%) were observed after 12 weeks of oral administration of 100 or 300 mg CBD daily, respectively. The two participants self-reported consuming 95.3% and 98.8% of CBD doses, respectively. CBD and select metabolites were measurable in plasma after 4 and 12 weeks of CBD treatment. No notable changes in sleep disturbance, depression, anxiety, stress, or quality of life were observed. Conclusions: CBD was well tolerated after 12 weeks of twice-daily oral administration and was associated with reduction in measured markers of bone turnover. Compliance with CBD treatment was good. Large-scale randomized clinical trials into the bone protective effects of CBD in postmenopausal women are warranted.

Sex Differences in the Safety and Subjective Effects of Two Oral Δ9-Tetrahydrocannabinol-Containing Cannabis Products over Multiple Doses Among Healthy Adults

Introduction: A growing number of females report consuming cannabis products. There is a paucity of data on sex differences in safety and subjective effects after repeated use of varying oral doses of Δ9-tetrahydrocannabinol (THC; the primary psychoactive constituent of cannabis). Materials and Methods: Data were from two randomized, double-blind, placebo-controlled, multiple-dose, between-subject trials of two THC-containing oral cannabis products. Healthy adults received placebo, low-dose THC (∼2.5 or ∼5 mg per dose), or high-dose THC (∼7.5 or ∼10 mg per dose) twice daily for 7 days. There were 38 males (8 placebo, 17 low-dose THC, 13 high-dose THC) and 46 females (8 placebo, 17 low-dose THC, 21 high-dose THC). Analyses compared adverse events (AEs) and subjective effects between males and females, by THC dose. Results: In the placebo and low-dose THC groups, there were no sex differences in the relative rate of AEs. In the high-dose THC group, females versus males reported 3.08 (95% confidence interval [CI]=1.31-8.33) times as many AEs. There were no significant interactions of sex×low-dose THC group for any subjective effect. In the high-dose THC group, females versus males reported greater "relaxed" ratings (b=15.14, 95% CI=1.44-28.84, p=0.027), whereas in the placebo group, males versus females reported greater ratings of "liking the effect" (b=-30.01, 95% CI=2.77-57.26, p=0.028). Although analyses were underpowered to assess the sex×THC dose×day interaction, the initial sex disparity in AEs and some subjective effects in the high-dose THC group appeared to shrink after the first day. Conclusions: In this exploratory analysis, sex differences in some responses to oral THC were nuanced. Females appeared more sensitive than males to AEs and some subjective effects at higher but not lower doses. Males reported higher ratings than females on some subjective effects in response to placebo. Initial sex differences in response to higher doses of oral THC tended to diminish over 7 days of dosing. If replicated, findings could help inform sex-specific dosing strategies of medical cannabis products and could help educate medical cannabis patients on any temporality of effects.

Sex Differences in the Pharmacokinetics of Cannabidiol and Metabolites Following Oral Administration of a Cannabidiol-Dominant Cannabis Oil in Healthy Adults

Introduction: Oral cannabidiol (CBD) product use is increasingly growing among women; however, there is a lack of data on sex differences in the pharmacokinetics (PKs) of CBD and its primary metabolites, 7-hydroxy-CBD (7-OH-CBD) and 7-carboxy-CBD (7-COOH-CBD), after repeated doses. Materials and Methods: The present study is a secondary analysis of data from a randomized, double-blind, placebo-controlled multiple-dose trial of a commercially available, CBD-dominant oral cannabis product. Healthy participants (n=17 males and 15 females) were randomized to receive 120 to 480 mg of CBD daily for 7 days. Dosing groups were pooled for all analyses due to sample size limitations. Analyses compared plasma PK parameters by sex, day, and sex×day. Results: For raw PK parameters for CBD and metabolites, there were no statistically significant effects of sex×day or sex (all p-values >0.05). For metabolite-to-parent ratios (MPRs) of AUC_0-t, there were significant effects of the sex×day interactions for 7-OH-CBD (F=6.89, p=0.016) and 7-COOH-CBD (F=5.96, p=0.021). For 7-OH-CBD, follow-up analyses showed significant simple effects of day within females (t=4.13, p<0.001), but not within males (t=0.34, p=0.73), such that 7-OH-CBD MPRs increased significantly from day 1 to 7 for females, but not for males. For 7-COOH-CBD, follow-up analyses revealed significant simple effects of day within females (t=8.24, p<0.001) and males (t=5.20, p<0.001), therefore 7-COOH-CBD MPRs increased significantly from day 1 to 7 in both sexes, but the increase was significantly greater among females than among males. Within dosing days, there were no statistically significant simple effects of sex on MPRs of 7-OH-CBD or 7-COOH-CBD. Conclusions: Females exhibited greater relative exposure to CBD metabolites in plasma over time, which may reflect sex differences in CBD metabolism or elimination. Further research assessing the safety implications of higher relative exposure to CBD metabolites over longer periods of time is warranted to mirror typical consumer use patterns.

A double-blind, randomized, placebo-controlled test of the effects of cannabidiol on fear elicited by a 10% carbon dioxide-enriched air breathing challenge

OBJECTIVE

A single administration of cannabidiol (CBD) can reduce anxiety during social anxiety inductions. No study, however, has evaluated the impact of CBD on fear responding among humans.

METHOD

A double-blind, randomized, placebo-controlled trial was undertaken to address this gap in the literature. Specifically, the current study tested a single oral administration of CBD (either 150 mg, 300 mg, or 600 mg), compared to placebo, for reducing fear reactivity to a well-established 5-min administration of 10% carbon dioxide (CO2)-enriched air biological challenge. CBD was administered 90 min prior to the challenge. Participants were 61 healthy young adults who self-reported fear continuously during the challenge. Heart rate also was continuously monitored, and panic symptoms were self-reported using the Diagnostic Sensations Questionnaire immediately following the procedure.

RESULTS

Results indicated no effect of condition on self-reported fear, panic symptoms, or heart rate.

CONCLUSION

This is the first study to document that CBD does not reduce fear reactivity in humans, thereby representing an important extension to research on the effects of CBD.

Associations between depression and cardiometabolic health: A 27-year longitudinal study

BACKGROUND

Clarifying the relationship between depression symptoms and cardiometabolic and related health could clarify risk factors and treatment targets. The objective of this study was to assess whether depression symptoms in midlife are associated with the subsequent onset of cardiometabolic health problems.

METHODS

The study sample comprised 787 male twin veterans with polygenic risk score data who participated in the Harvard Twin Study of Substance Abuse ('baseline') and the longitudinal Vietnam Era Twin Study of Aging ('follow-up'). Depression symptoms were assessed at baseline [mean age 41.42 years (s.d. = 2.34)] using the Diagnostic Interview Schedule, Version III, Revised. The onset of eight cardiometabolic conditions (atrial fibrillation, diabetes, erectile dysfunction, hypercholesterolemia, hypertension, myocardial infarction, sleep apnea, and stroke) was assessed via self-reported doctor diagnosis at follow-up [mean age 67.59 years (s.d. = 2.41)].

RESULTS

Total depression symptoms were longitudinally associated with incident diabetes (OR 1.29, 95% CI 1.07-1.57), erectile dysfunction (OR 1.32, 95% CI 1.10-1.59), hypercholesterolemia (OR 1.26, 95% CI 1.04-1.53), and sleep apnea (OR 1.40, 95% CI 1.13-1.74) over 27 years after controlling for age, alcohol consumption, smoking, body mass index, C-reactive protein, and polygenic risk for specific health conditions. In sensitivity analyses that excluded somatic depression symptoms, only the association with sleep apnea remained significant (OR 1.32, 95% CI 1.09-1.60).

CONCLUSIONS

A history of depression symptoms by early midlife is associated with an elevated risk for subsequent development of several self-reported health conditions. When isolated, non-somatic depression symptoms are associated with incident self-reported sleep apnea. Depression symptom history may be a predictor or marker of cardiometabolic risk over decades.

Medical cannabis authorization patterns, safety, and associated effects in older adults

Background

Use of medical cannabis is increasing among older adults. However, few investigations have examined cannabis use in this population.

Methods

We assessed the authorization patterns, safety, and effects of medical cannabis in a sub-analysis of 201 older adults (aged ≥ 65 years) who completed a 3-month follow-up during this observational study of patients who were legally authorized a medical cannabis product (N = 67). Cannabis authorization patterns, adverse events (AEs), Edmonton Symptom Assessment Scale-revised (ESAS-r), and Brief Pain Inventory Short Form (BPI-SF) data were collected.

Results

The most common symptoms for which medical cannabis was authorized were pain (159, 85.0%) and insomnia (9, 4.8%). At baseline and at the 3-month follow-up, cannabidiol (CBD)-dominant products were authorized most frequently (99, 54%), followed by balanced products (76, 42%), and then delta-9-tetrahydrocannabinol (THC)-dominant products (8, 4.4%). The most frequent AEs were dizziness (18.2%), nausea (9.1%), dry mouth (9.1%), and tinnitus (9.1%). Significant reductions in ESAS-r scores were observed over time in the domains of drowsiness (p = .013) and tiredness (p = .031), but not pain (p = .106) or well-being (p = .274). Significant reductions in BPI-SF scores over time were observed for worst pain (p = .010), average pain (p = .012), and overall pain severity (p = 0.009), but not pain right now (p = .052) or least pain (p = .141).

Conclusions

Overall, results suggest medical cannabis was safe, well-tolerated, and associated with clinically meaningful reductions in pain in this sample of older adults. However, the potential bias introduced by the high subject attrition rate means that all findings should be interpreted cautiously and confirmed by more rigorous studies.

Cognitive Reserve and Related Constructs: A Unified Framework Across Cognitive and Brain Dimensions of Aging

Cognitive reserve and related constructs are valuable for aging-related research, but consistency and clarification of terms is needed as there is still no universally agreed upon nomenclature. We propose a new set of definitions for the concepts of reserve, maintenance, and resilience, and we invoke parallel concepts for each that are applicable to cognition and to brain. Our definitions of reserve and resilience correspond reasonably well to dictionary definitions of these terms. We demonstrate logical/methodological problems that arise from incongruence between commonly used conceptual and operational definitions. In our view, cognitive reserve should be defined conceptually as one's total cognitive resources at a given point in time. IQ and education are examples of common operational definitions (often referred to as proxies) of cognitive reserve. Many researchers define cognitive reserve conceptually as a property that allows for performing better than expected cognitively in the face of aging or pathology. Performing better than expected is demonstrated statistically by interactions in which the moderator is typically IQ or education. The result is an irreconcilable situation in which cognitive reserve is both the moderator and the moderation effect itself. Our proposed nomenclature resolves this logical inconsistency by defining performing better than expected as cognitive resilience. Thus, in our usage, we would test the hypothesis that high cognitive reserve confers greater cognitive resilience. Operational definitions (so-called proxies) should not conflate factors that may influence reserve-such as occupational complexity or engagement in cognitive activities-with cognitive reserve itself. Because resources may be depleted with aging or pathology, one's level of cognitive reserve may change over time and will be dependent on when assessment takes place. Therefore, in addition to cognitive reserve and cognitive resilience, we introduce maintenance of cognitive reserve as a parallel to brain maintenance. If, however, education is the measure of reserve in older adults, it precludes assessing change or maintenance of reserve. Finally, we discuss consideration of resistance as a subcategory of resilience, reverse causation, use of residual scores to assess performing better than expected given some adverse factor, and what constitutes high vs. low cognitive reserve across different studies.

Longitudinal Relationship between the Introduction of Medicinal Cannabis and Polypharmacy: An Australian Real-World Evidence Study

BACKGROUND

Recent studies recommend medicinal cannabis (MC) as a potential treatment for chronic pain (CP) when conventional therapies are not successful; however, data from Australia is limited. This real-world evidence study explored how the introduction of MC related to concomitant medication use over time. Long-term safety also was examined.

METHODS

Data were collected by the Emerald Clinics (a network of seven clinics located across Australia) as part of routine practice from Jan 2020 toJan 2021. Medications were classified by group: antidepressants, benzodiazepines, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and total number of medications. Adverse events (AEs) were collected at each visit and subsequently coded using the Medical Dictionary for Regulatory Activities version 23 into the system organ class (SOC) and preferred term (PT). A total of 535 patients were analyzed.

RESULTS

The most common daily oral dose was 10 mg for delta-9-tetrahydrocannabinol (THC) and 15 mg for cannabidiol (CBD). With the introduction of MC, patients' total number of medications consumed decreased over the course of one year; significant reductions in NSAIDs, benzodiazepines, and antidepressants were observed (p < .001). However, the number of prescribed opioid medications did not differ from baseline to the end of one year (p = .49). Only 6% of patients discontinued MC treatment during the study. A total of 600 AEs were reported in 310 patients during the reporting period and 97% of them were classified as nonserious. Discussion. Though observational in nature, these findings suggest MC is generally well-tolerated, consistent with the previous literature, and may reduce concomitant use of some medications. Due to study limitations, concomitant medication reductions cannot be causally attributed to MC. Nevertheless, these data underscore early signals that warrant further exploration in randomized trials.

Cognitive Reserve and Related Constructs: A Unified Framework Across Cognitive and Brain Dimensions of Aging

Cognitive reserve and related constructs are valuable for aging-related research, but consistency and clarification of terms is needed as there is still no universally agreed upon nomenclature. We propose a new set of definitions for the concepts of reserve, maintenance, and resilience, and we invoke parallel concepts for each that are applicable to cognition and to brain. Our definitions of reserve and resilience correspond reasonably well to dictionary definitions of these terms. We demonstrate logical/methodological problems that arise from incongruence between commonly used conceptual and operational definitions. In our view, cognitive reserve should be defined conceptually as one's total cognitive resources at a given point in time. IQ and education are examples of common operational definitions (often referred to as proxies) of cognitive reserve. Many researchers define cognitive reserve conceptually as a property that allows for performing better than expected cognitively in the face of aging or pathology. Performing better than expected is demonstrated statistically by interactions in which the moderator is typically IQ or education. The result is an irreconcilable situation in which cognitive reserve is both the moderator and the moderation effect itself. Our proposed nomenclature resolves this logical inconsistency by defining performing better than expected as cognitive resilience. Thus, in our usage, we would test the hypothesis that high cognitive reserve confers greater cognitive resilience. Operational definitions (so-called proxies) should not conflate factors that may influence reserve-such as occupational complexity or engagement in cognitive activities-with cognitive reserve itself. Because resources may be depleted with aging or pathology, one's level of cognitive reserve may change over time and will be dependent on when assessment takes place. Therefore, in addition to cognitive reserve and cognitive resilience, we introduce maintenance of cognitive reserve as a parallel to brain maintenance. If, however, education is the measure of reserve in older adults, it precludes assessing change or maintenance of reserve. Finally, we discuss consideration of resistance as a subcategory of resilience, reverse causation, use of residual scores to assess performing better than expected given some adverse factor, and what constitutes high vs. low cognitive reserve across different studies.

Paradoxical cognitive trajectories in men from earlier to later adulthood

Because longitudinal studies of aging typically lack cognitive data from earlier ages, it is unclear how general cognitive ability (GCA) changes throughout the life course. In 1173 Vietnam Era Twin Study of Aging (VETSA) participants, we assessed young adult GCA at average age 20 and current GCA at 3 VETSA assessments beginning at average age 56. The same GCA index was used throughout. Higher young adult GCA and better GCA maintenance were associated with stronger specific cognitive abilities from age 51 to 73. Given equivalent GCA at age 56, individuals who had higher age 20 GCA outperformed those whose GCA remained stable in terms of memory, executive function, and working memory abilities from age 51 to 73. Thus, paradoxically, despite poorer maintenance of GCA, high young adult GCA still conferred benefits. Advanced predicted brain age and the combination of elevated vascular burden and APOE-ε4 status were associated with poorer maintenance of GCA. These findings highlight the importance of distinguishing between peak and current GCA for greater understanding of cognitive aging.

12-year prediction of mild cognitive impairment aided by Alzheimer's brain signatures at mean age 56

Neuroimaging signatures based on composite scores of cortical thickness and hippocampal volume predict progression from mild cognitive impairment to Alzheimer's disease. However, little is known about the ability of these signatures among cognitively normal adults to predict progression to mild cognitive impairment. Towards that end, a signature sensitive to microstructural changes that may predate macrostructural atrophy should be useful. We hypothesized that: (i) a validated MRI-derived Alzheimer's disease signature based on cortical thickness and hippocampal volume in cognitively normal middle-aged adults would predict progression to mild cognitive impairment; and (ii) a novel grey matter mean diffusivity signature would be a better predictor than the thickness/volume signature. This cohort study was part of the Vietnam Era Twin Study of Aging. Concurrent analyses compared cognitively normal and mild cognitive impairment groups at each of three study waves (ns = 246-367). Predictive analyses included 169 cognitively normal men at baseline (age = 56.1, range = 51-60). Our previously published thickness/volume signature derived from independent data, a novel mean diffusivity signature using the same regions and weights as the thickness/volume signature, age, and an Alzheimer's disease polygenic risk score were used to predict incident mild cognitive impairment an average of 12 years after baseline (follow-up age = 67.2, range = 61-71). Additional analyses adjusted for predicted brain age difference scores (chronological age minus predicted brain age) to determine if signatures were Alzheimer-related and not simply ageing-related. In concurrent analyses, individuals with mild cognitive impairment had higher (worse) mean diffusivity signature scores than cognitively normal participants, but thickness/volume signature scores did not differ between groups. In predictive analyses, age and polygenic risk score yielded an area under the curve of 0.74 (sensitivity = 80.00%; specificity = 65.10%). Prediction was significantly improved with addition of the mean diffusivity signature (area under the curve = 0.83; sensitivity = 85.00%; specificity = 77.85%; P = 0.007), but not with addition of the thickness/volume signature. A model including both signatures did not improve prediction over a model with only the mean diffusivity signature. Results held up after adjusting for predicted brain age difference scores. The novel mean diffusivity signature was limited by being yoked to the thickness/volume signature weightings. An independently derived mean diffusivity signature may thus provide even stronger prediction. The young age of the sample at baseline is particularly notable. Given that the brain signatures were examined when participants were only in their 50 s, our results suggest a promising step towards improving very early identification of Alzheimer's disease risk and the potential value of mean diffusivity and/or multimodal brain signatures.

Authorization Patterns, Safety, and Effectiveness of Medical Cannabis in Quebec

Introduction: Despite increasing demand for data, little is known about the authorization patterns, safety, and effectiveness of medical cannabis products.

Materials and Methods: We conducted a 2 year observational study of adult patients who were legally authorized a medical cannabis product from a single licensed producer; we captured and analyzed authorized cannabis use patterns by cannabinoid profile (tetrahydrocannabinol [THC]-dominant; cannabidiol [CBD]-dominant; and balanced (THC:CBD) and clinical outcomes using standardized outcome measures every 3 months for 12 months at a network of medical cannabis clinics in Quebec, Canada.

Results: We recruited 585 patients (average age 56.5 years), of whom 61% identified as female and 85% reported pain as their primary complaint. Over 12 months, there was a significant increase in the number of products authorized (Z=2.59, p=0.01). The proportion of authorizations for a THC-dominant or CBD-dominant product increased relative to the proportion of authorizations for a balanced (THC:CBD) product (all p<0.01). Symptom improvement over time was observed for pain, tiredness, drowsiness, anxiety, and well-being. Patients authorized THC-dominant products exhibited less symptom improvement for anxiety and well-being relative to those authorized CBD-dominant or balanced (THC:CBD) products. Medical cannabis was well tolerated across all product profiles.

Conclusion: These real-world data reveal changes in medical cannabis authorization patterns and suggest that symptom improvement may vary by cannabinoid profile over 12 months of follow-up.

MRI-assessed locus coeruleus integrity is heritable and associated with multiple cognitive domains, mild cognitive impairment, and daytime dysfunction

Introduction

The locus coeruleus (LC) undergoes extensive neurodegeneration in early Alzheimer's disease (AD). The LC is implicated in regulating the sleep–wake cycle, modulating cognitive function, and AD progression.

Methods

Participants were 481 men (ages 62 to 71.7) from the Vietnam Era Twin Study of Aging. LC structural integrity was indexed by neuromelanin‐sensitive magnetic resonance imaging (MRI) contrast‐to‐noise ratio (LC_CNR). We examined LC_CNR, cognition, amnestic mild cognitive impairment (aMCI), and daytime dysfunction.

Results

Heritability of LC_CNR was .48. Participants with aMCI showed greater daytime dysfunction. Lower LC_CNR was associated with poorer episodic memory, general verbal fluency, semantic fluency, and processing speed, as well as increased odds of aMCI and greater daytime dysfunction.

Discussion

Reduced LC integrity is associated with widespread differences across cognitive domains, daytime sleep‐related dysfunction, and risk for aMCI. These findings in late‐middle‐aged adults highlight the potential of MRI‐based measures of LC integrity in early identification of AD risk.

APOE interacts with tau PET to influence memory independently of amyloid PET in older adults without dementia

INTRODUCTION

Apolipoprotein E (APOE) interacts with Alzheimer's disease pathology to promote disease progression. We investigated the moderating effect of APOE on independent associations of amyloid and tau positron emission tomography (PET) with cognition.

METHODS

For 297 nondemented older adults from the Alzheimer's Disease Neuroimaging Initiative, regression equations modeled associations between cognition and (1) cortical amyloid beta (Aβ) PET levels adjusting for tau and (2) medial temporal lobe (MTL) tau PET levels adjusting for Aβ, including interactions with APOE ε4-carrier status.

RESULTS

Adjusting for tau PET, Aβ was not associated with cognition and did not interact with APOE. In contrast, adjusting for Aβ PET, MTL tau was associated with all cognitive domains. Further, there was a stronger moderating effect of APOE on MTL tau and memory associations in ε4-carriers, even among Aβ-negative individuals.

DISCUSSION

Findings suggest that APOE may interact with tau independently of Aβ and that elevated MTL tau confers negative cognitive consequences in Aβ-negative ε4 carriers.

Hypertension and Alzheimer's disease: indirect effects through circle of Willis atherosclerosis

Hypertension is common among older adults and is believed to increase susceptibility to Alzheimer's disease, but mechanisms underlying this relationship are unclear. Hypertension also promotes circle of Willis atherosclerosis, which contributes to cerebral hypoperfusion and arterial wall stiffening, two potential mechanisms linking hypertension to Alzheimer's disease. To examine the role of circle of Willis atherosclerosis in the association between hypertension and Alzheimer's disease neuropathology, we analysed post-mortem neuropathological data on 2198 decedents from the National Alzheimer's Coordinating Center database [mean (standard deviation) age at last visit 80.51 (1.95) and 47.1% female] using joint simultaneous (i.e. mediation) modelling. Within the overall sample and among Alzheimer's dementia decedents, hypertension was indirectly associated with increased neuritic plaques and neurofibrillary tangles through its association with circle of Willis atherosclerosis. Similar indirect effects were observed for continuous measures of systolic and diastolic blood pressure. These results suggest that hypertension may promote Alzheimer's disease pathology indirectly through intracranial atherosclerosis by limiting cerebral blood flow and/or dampening perivascular clearance. Circle of Willis atherosclerosis may be an important point of convergence between vascular risk factors, cerebrovascular changes and Alzheimer's disease neuropathology.

Attitude Toward Own Aging Among Older Adults: Implications for Cancer Prevention

BACKGROUND AND OBJECTIVES

Negative age stereotypes can become internalized and contribute to lower levels of physical and mental well-being in older adults, including those with serious illnesses. The main objective of this study was to examine the relationships of attitude toward own aging (ATOA) with health outcomes after controlling for resilience among older cancer survivors and comparison subjects without cancer, aged 50 years or older.

METHODS

We examined data in 1,140 adults from the Successful Aging Evaluation (SAGE) study, a structured multi-cohort investigation of community-based adults selected using random digit dialing. There were 219 participants with cancer (excluding skin cancer) and 912 without cancer. ATOA was assessed with the Philadelphia Geriatric Morale Scale, and its relationship with measures of physical, cognitive, and mental health, as well as resilience was evaluated.

RESULTS

Individuals with cancer reported slightly more pessimistic ATOA than individuals without cancer. ATOA correlated with physical and mental health in individuals with and without cancer. Hierarchical linear multiple regression revealed that ATOA contributed significantly to the prediction of physical and mental health after controlling for socio-demographic variables and resilience.

DISCUSSION AND IMPLICATIONS

Higher levels of positive ATOA appear to be a protective factor for health in older adults, including those with cancer. Interventions that provide education about positive aspects of aging, modify negative automatic thoughts, and promote optimism may be useful for increasing ATOA and thereby improving physical and mental health in older adults, especially those with cancer.

Factor Analysis of the Apathy Scale in Parkinson's Disease

Background

The Apathy Scale (AS), a popular measure of apathy in Parkinson's disease (PD), has been somewhat limited for failing to characterize dimensions of apathy, such as those involving cognitive, behavioral, and emotional apathy symptoms. This study sought to determine whether factors consistent with these apathy dimensions in PD could be identified on the AS, examine the associations between these factors and disease-related characteristics, and compare PD patients and healthy control (HCs) on identified factors.

Methods

Confirmatory (CFA) and exploratory factor analysis (EFA) were conducted on AS scores of 157 nondemented PD patients to identify AS factors. These factors were then correlated with important disease-related characteristics, and PD and HC participants were compared across these factors.

Results

Previously proposed AS models failed to achieve an adequate fit in CFA. A subsequent EFA revealed two factors on the AS reflecting joint cognitive-behavioral aspects of apathy (Motivation-Interest-Energy) and emotional apathy symptoms (Indifference). Both factors were associated with anxiety, depression, health-related quality of life, and independent activities of daily living, with Indifference associated more with the latter. In addition, only the Indifference factor was associated with cognitive functioning. PD patients reported higher levels of symptoms than HCs on both factors, with the group difference slightly larger on the Motivation-Interest-Energy factor.

Conclusion

The AS can be decomposed into two factors reflecting Motivation-Interest-Energy and Indifference symptoms. These factors are differentially associated with clinical variables, including cognition and independent activities of daily living, indicating the importance of evaluating apathy from a multidimensional perspective.

Loneliness in schizophrenia: Construct clarification, measurement, and clinical relevance

Loneliness is a highly prevalent experience in schizophrenia. Theoretical models developed in the general population propose that loneliness is tantamount to a feeling of being unsafe, is accompanied by enhanced environmental threat perception, and leads to poor physical, emotional, and cognitive functioning. Previous research has reported that loneliness is associated with poorer physical and emotional health in schizophrenia; however, few studies have directly compared loneliness and its correlates in persons with schizophrenia and non-psychiatric comparison subjects. The purpose of the current study was to evaluate similarities and differences in the construct of loneliness, the equivalency of the measurement of this construct, and similarities and differences in the pattern of external correlates of loneliness between schizophrenia and non-psychiatric comparison groups. The third version of the University of California, Los Angeles Loneliness Scale (UCLA-3) was administered to 116 individuals with schizophrenia or schizoaffective disorder and 106 non-psychiatric comparison subjects. Additional clinical and positive psychological measures were collected, as well as demographic characteristics of the two groups. Multiple groups confirmatory factor analysis revealed that the UCLA-3 was best characterized by a bifactor model in which all items loaded on a general loneliness dimension as well as one of two orthogonal method factors reflecting item wording in both groups. Furthermore, the UCLA-3 exhibited invariant measurement of these latent constructs across groups. Mean levels of loneliness were nearly a standard deviation higher in the schizophrenia group. Nonetheless, the overall pattern and strength of correlates were largely similar across groups, with loneliness being positively associated with depression, anxiety, and perceived stress, and negatively correlated with mental well-being, happiness, and resilience. Subtle differences in correlates of age, optimism, and satisfaction with life were found. Overall, loneliness appears to be distinct from other schizophrenia-related deficits and operates similarly across schizophrenia and NC groups, suggesting that theoretical models of loneliness developed in the general population may generalize to schizophrenia.