Norwegian population-based study of effectiveness of vagus nerve stimulation in patients with developmental and epileptic encephalopathies

OBJECTIVE

Evaluate the long-term efficacy of vagus nerve stimulation (VNS) in patients with developmental and epileptic encephalopathies (DEE) compared with epilepsy patients without intellectual disability (ID).

METHODS

Long-term outcomes from a Norwegian VNS quality registry are reported in 105 patients with DEEs (Lennox-Gastaut syndrome [LGS] n = 62; Dravet n = 16; Rett n = 9; other syndromes n = 18) were compared with 212 epilepsy patients without ID, with median follow-up of 88 and 72 months, respectively. Total seizure reduction was evaluated at 6, 12, 24, 36, and 60 months. Effect on different seizure types was evaluated at baseline and last observation carried forward (LOCF).

RESULTS

Median monthly seizure frequency at LOCF was reduced by 42.2% (p < 0.001) in patients with DEE and by 55.8% (p < 0.001) in patients without ID. In DEE patients, ≥50% seizure reduction at 6 and 24 months were 17.1% and 37.1%, respectively, and 33.5% and 48.6% for patients without ID. Seizure reduction ≥75% at 60 months occurred in 14.3% of DEE patients and 23.1% of patients without ID. Highest median reduction was for atonic seizures, most notably 64.6% for LGS patients. A better effect was seen at 2 years among DEE patients with unchanged medication compared with those with changed medication (54.5% vs. 35.6% responders, p = 0.078). More DEE patients were reported to have greater improvement in ictal or postictal severity (43.8% vs. 28.3%, p = 0.006) and alertness (62.9% vs. 31.6%, p < 0.001) than patients without ID. For both groups, use of the magnet reduced seizure severity. Hoarseness was the most common adverse effect in both groups. In addition, DEE patients were frequently reported to have sleep disturbance, general discomfort, or abdominal problems.

SIGNIFICANCE

Our data indicate that VNS is very effective for atonic seizures. Patients without ID had best overall seizure reduction, however, patients with DEE had higher retention rates probably due to other positive effects.

PLAIN LANGUAGE SUMMARY

DEE refers to a group of patients with severe epilepsy and intellectual disability. Many of these patients have restricted lifestyles with frequent seizures. VNS is a treatment option for patients who do not respond well to medicines, either because of insufficient effect or serious adverse effects. Our study shows that VNS is well tolerated in this patient group and leads to a reduction in all seizure types, most notably for seizures leading to fall. Many patients experience other positive effects like shorter and milder seizures, as well as improvement in alertness.

When do the effects of single-session interventions persist? Testing the mindset + supportive context hypothesis in a longitudinal randomized trial

Background

Single-session interventions have the potential to address young people's mental health needs at scale, but their effects are heterogeneous. We tested whether the mindset + supportive context hypothesis could help explain when intervention effects persist or fade over time. The hypothesis posits that interventions are more effective in environments that support the intervention message. We tested this hypothesis using the synergistic mindsets intervention, a preventative treatment for stress-related mental health symptoms that helps students appraise stress as a potential asset in the classroom (e.g., increasing oxygenated blood flow) rather than debilitating. In an introductory college course, we examined whether intervention-consistent messages from instructors sustained changes in appraisals over time, as well as impacts on students' predisposition to try demanding academic tasks that could enhance learning.

Methods

We randomly assigned 1675 students in the course to receive the synergistic mindsets intervention (or a control activity) at the beginning of the semester, and subsequently, to receive intervention-supportive messages from their instructor (or neutral messages) four times throughout the term. We collected weekly measures of students' appraisals of stress in the course and their predisposition to take on academic challenges. Trial-registration: OSF.io; DOI: 10.17605/osf.io/fchyn.

Results

A conservative Bayesian analysis indicated that receiving both the intervention and supportive messages led to the greatest increases in positive stress appraisals (0.35 SD; 1.00 posterior probability) and challenge-seeking predisposition (2.33 percentage points; 0.94 posterior probability), averaged over the course of the semester. In addition, intervention effects grew larger throughout the semester when complemented by supportive instructor messages, whereas without these messages, intervention effects shrank somewhat over time.

Conclusions

This study shows, for the first time, that supportive cues in local contexts can be the difference in whether a single-session intervention's effects fade over time or persist and even amplify.

Context-dependent effects of a reintroduced ungulate on soil properties are driven by soil texture, moisture, and herbivore activity

Although there is considerable evidence that large mammalian herbivores influence ecosystem-level processes, studies have reported such widely varying results that generalizations have remained elusive. Here, we use an 18-year-old exclosure experiment-stratified across a landscape heterogeneous with respect to soil texture, moisture and herbivore activity-to understand the variable effects of tule elk (Cervus canadensis nannodes), a native reintroduced herbivore, on soil properties along the coast of northern California. Elk significantly increased soil bulk density and created a compacted layer at shallow soil depth, while decreasing infiltration rate and pH. The effects of elk on bulk density, penetration resistance, and pH varied with soil type, being least pronounced in coarse, sandy loams, and greatest in loose sand. The effects of elk on nutrient availability varied along gradients of soil texture and moisture. In coarser soils, elk decreased ammonium availability, but increased it in finer soils. Elk also decreased soil moisture content, in part through their positive effect on bulk density, and this effect was most pronounced in coarser soils. Through decreasing soil moisture content, elk also decreased nitrate availability in coarser soils. At greater levels of elk activity (as measured by dung deposition), the elk effect on bulk density was amplified, and this had a corresponding negative effect on nitrate and phosphate availability. Our study has demonstrated that a better understanding of spatial variation in the effects of herbivores on ecosystems can emerge by evaluating their influences across gradients of soil texture, soil moisture, and herbivore activity. These data enabled us to evaluate several frameworks that have been developed to understand the variable effects of herbivores on ecosystems, which is a significant step in reconciling the many competing ideas put forth to explain the context-dependent effects of large herbivores on grazed ecosystems.

Lost Generations: Long-Term Effects of the COVID-19 Crisis on Job Losers and Labour Market Entrants, and Options for Policy

This paper discusses the potential long-run effects of large-scale unemployment during the COVID-19 crisis in the labour market on vulnerable job losers and labour market entrants in the United States. The paper begins by contrasting measures of the scale of job loss during the crisis. These measures are paired with estimates from past recessions indicating that the costs of job loss and unemployment can reduce workers' earnings and raise their mortality for several decades. Focusing only on a subset of vulnerable job losers, the potential lifetime earnings losses from job loss related to the COVID-19 pandemic are predicted to be up to $2 trillion. Related losses in employment could imply a lasting reduction in the overall employment-population ratio. For these workers, losses in potential life years could be up to 24 million. Even at the low range, the resulting estimates are substantially larger than losses in potential life years from deaths directly due to COVID-19. New labour market entrants are at risk to suffer long-term losses in earnings and mortality as well. Based partly on experiences in other countries, the paper discusses potential reforms to short-time compensation programmes and unemployment insurance, which could help limit the short- and long-term harm from layoffs going forward.

Cross-seasonal legacy effects of arthropod community on plant fitness in perennial plants

In perennial plants, interactions with other community members during the vegetative growth phase may influence community assembly during subsequent reproductive years and may influence plant fitness. It is well-known that plant responses to herbivory affect community assembly within a growing season, but whether plant-herbivore interactions result in legacy effects on community assembly across seasons has received little attention. Moreover, whether plant-herbivore interactions during the vegetative growing season are important in predicting plant fitness directly or indirectly through legacy effects is poorly understood.Here, we tested whether plant-arthropod interactions in the vegetative growing season of perennial wild cabbage plants, Brassica oleracea, result in legacy effects in arthropod community assembly in the subsequent reproductive season and whether legacy effects have plant fitness consequences. We monitored the arthropod community on plants that had been induced with either aphids, caterpillars or no herbivores in a full-factorial design across 2 years. We quantified the plant traits 'height', 'number of leaves' and 'number of flowers' to understand mechanisms that may mediate legacy effects. We measured seed production in the second year to evaluate plant fitness consequences of legacy effects.Although we did not find community responses to the herbivory treatments, our data show that community composition in the first year leaves a legacy on community composition in a second year: predator community composition co-varied across years. Structural equation modelling analyses indicated that herbivore communities in the vegetative year correlated with plant performance traits that may have caused a legacy effect on especially predator community assembly in the subsequent reproductive year. Interestingly, the legacy of the herbivore community in the vegetative year predicted plant fitness better than the herbivore community that directly interacted with plants in the reproductive year. Synthesis. Thus, legacy effects of plant-herbivore interactions affect community assembly on perennial plants across growth seasons and these processes may affect plant reproductive success. We argue that plant-herbivore interactions in the vegetative phase as well as in the cross-seasonal legacy effects caused by plant responses to arthropod herbivory may be important in perennial plant trait evolution such as ontogenetic variation in growth and defence strategies.

Native herbivores and environmental heterogeneity as mediators of an exotic grass invasion

Given that many exotic plant species throughout the world are having large ecological and economic effects, it is vital to understand the forces that mediate their success in novel landscapes. Both native herbivores and recipient ecosystems can have substantial effects on the performance of exotic plant species, and may interact with each other or vary in their effects over time. Unfortunately, few studies have evaluated the importance of these kinds of context‐dependent effects. Here, we use a 17‐year‐old exclosure experiment stratified across a coastal grassland in northern California to address the relative importance of a reintroduced mammalian herbivore, tule elk (Cervus canadensis nannodes), and environmental heterogeneity in mediating the growth, abundance, and recruitment of a problematic grass invader, Holcus lanatus. We found that elk reduced Holcus abundance, aboveground biomass, percent cover, frequency, and seedling recruitment, but that these effects often varied among habitat types, with effects being greater in open grasslands than shrub‐dominated grasslands. The performance of Holcus populations also varied significantly among habitat types, with the invader usually having the greatest success in Baccharis‐dominated grasslands. Our results suggest that environmental heterogeneity had much greater influence on Holcus success than elk, and that these effects were due largely to soil pH and moisture. The negative effects of elk on Holcus appeared after 4 years and did not intensify after an additional 13 years. Furthermore, despite their negative effects, these prominent herbivores did not prevent the spread of Holcus into previously uninvaded areas. Our research highlights the importance of assessing the individual and interactive effects of native herbivores and environmental heterogeneity on the success of invasive, exotic plant species. It emphasizes the reality that the negative effects of herbivores on exotic plant species will often vary across heterogeneous landscapes and may be insufficient to prevent the expansion of these invaders.