Invasive tree cover covaries with environmental factors to explain the functional composition of riparian plant communities

Invasive species are a major cause of biodiversity loss worldwide, but their impact on communities and the mechanisms driving those impacts are varied and not well understood. This study employs functional diversity metrics and guilds-suites of species with similar traits-to assess the influence of an invasive tree (Tamarix spp.) on riparian plant communities in the southwestern United States. We asked: (1) What traits define riparian plant guilds in this system? (2) How do the abundances of guilds vary along gradients of Tamarix cover and abiotic conditions? (3) How does the functional diversity of the plant community respond to the gradients of Tamarix cover and abiotic conditions? We found nine distinct guilds primarily defined by reproductive strategy, as well as growth form, height, seed weight, specific leaf area, drought and anaerobic tolerance. Guild abundance varied along a covarying gradient of local and regional environmental factors and Tamarix cover. Guilds relying on sexual reproduction, in particular, those producing many light seeds over a long period of time were more strongly associated with drier sites and higher Tamarix cover. Tamarix itself appeared to facilitate more shade-tolerant species with higher specific leaf areas than would be expected in resource-poor environments. Additionally, we found a high degree of specialization (low functional diversity) in the wettest, most flood-prone, lowest Tamarix cover sites as well as in the driest, most stable, highest Tamarix cover sites. These guilds can be used to anticipate plant community response to restoration efforts and in selecting appropriate species for revegetation.

Efficacy of digital cognitive behavioural therapy for symptoms of generalised anxiety disorder: a study protocol for a randomised controlled trial

Background

Generalised anxiety disorder (GAD) is a chronic and disabling condition with considerable personal and economic impact. Cognitive behavioural therapy (CBT) is a recommended psychological therapy for GAD; however, there are substantial barriers to accessing treatment. Digital CBT, in particular smartphone-delivered CBT, has the potential to improve accessibility and increase dissemination of CBT. Despite the emerging evidence of smartphone-based psychological interventions for reducing anxiety, effect size scores are typically smaller than in-person interventions, and there is a lack of research assessing the efficacy of smartphone-delivered digital interventions specifically for GAD.

Methods

In the DeLTA trial (DigitaL Therapy for Anxiety), we plan to conduct a parallel-group superiority randomised controlled trial examining the efficacy of a novel smartphone-based digital CBT intervention for GAD compared to a waitlist control. We aim to recruit 242 adults (aged 18 years or above) with moderate-to-severe symptoms of GAD. This trial will be conducted entirely online and will involve assessments at baseline (week 0; immediately preceding randomisation), mid-intervention (week 3), post-intervention (week 6; primary end point) and follow-up (week 10). The primary objective is to evaluate the efficacy of the intervention on GAD symptom severity compared to a waitlist control at post-intervention. Secondary objectives are to examine between-group effects on GAD at follow-up, and to examine the following secondary outcomes at both post-intervention and follow-up: 1) worry; 2) depressive symptoms; 3) wellbeing; 4) quality of life; and 5) sleep difficulty.

Discussion

This trial will report findings on the initial efficacy of a novel digital CBT intervention for GAD. Results have the potential to contribute towards the evidence base for digital CBT for GAD and increase the dissemination of CBT.

Trial registration

ISRCTN, ISRCTN12765810. Registered on 11 January 2019.

Understanding the experience of sleep disturbance in psoriasis: a qualitative exploration using the Common-Sense Model of Self-Regulation

BACKGROUND

Psoriasis is associated with significant morbidity, which negatively impacts upon quality of life. Sleep disturbance is reported to be common in patients with psoriasis and is associated with physical and psychological variables, although there is little published work in this area. Understanding sleep and the factors involved in its disturbance in psoriasis is a potentially important clinical area given the role of sleep in health and disease processes.

OBJECTIVES

To explore the experience of sleep and sleep disturbance in psoriasis using the Common-Sense Model of Self-Regulation (CS-SRM).

METHODS

Semistructured interviews were conducted with adults diagnosed with psoriasis. Interview questions were informed by the CS-SRM and previous research. Framework analysis was applied, including coding data into the CS-SRM dimensions and allowing additional inductive themes to emerge.

RESULTS

Seventeen people with psoriasis (nine women, eight men; aged 19-86 years) were interviewed about sleep and sleep disturbance. Seven themes emerged, with six accounted for by the CS-SRM: characteristics of sleep disturbance, change in sleep patterns, thoughts about and symptoms of disease disturbing sleep, impact of poor sleep on daily life, attempts to improve sleep, a daily battle for control and a seventh relating to metacognitive processes. A reciprocal relationship between sleep and psoriasis was evident across themes with interactions between key sleep-related thoughts, emotions and behaviours.

CONCLUSIONS

This study showed that sleep disturbance is a persistent concern for people with psoriasis; it has a 24-h impact, and interacts with the psychological and physical aspects of psoriasis. The distress and frustration felt when managing sleep disturbance perpetuated problematic sleep. Addressing this with currently available sleep treatments may therefore confer sleep and psoriasis-related benefits for people living with this condition.

A cross-sectional survey of the nature and correlates of sleep disturbance in people with psoriasis

BACKGROUND

Research suggests that sleep disturbance is common in psoriasis. While several sleep investigations have been conducted in psoriasis populations, many have methodological shortcomings, and no study has examined multiple dimensions of sleep-wake functioning. Moreover, research has yet to be performed comprehensively examining the range of physical and psychological factors that may affect sleep in people with psoriasis.

OBJECTIVES

To characterize sleep disturbance using validated measures and to identify physical and psychological predictors of sleep quality in people with psoriasis.

METHODS

An online survey was conducted (186 respondents; mean age 39·2 years) comprising validated measures assessing sleep [Pittsburgh Sleep; Quality Index (PSQI), Berlin Questionnaire, Pre-Sleep Arousal Scale]; chronotype (Morningness-Eveningness Questionnaire); mood (Hospital Anxiety and Depression Scale); itch (5-D Itch Scale); and psoriasis severity (Simplified Psoriasis Index). Group comparisons and regression analyses were used to examine predictors of poor sleep.

RESULTS

The mean PSQI score was 9·2 ± 4·3, with 76·3% scoring above the threshold for poor sleep (≥ 6 on the PSQI) and 32·5% scoring 'positive' for probable obstructive sleep apnoea (OSA). Poor sleep and high likelihood of OSA were associated with more severe psoriasis (P < 0·05; η = 0·07; η² = 0·005). Cognitive arousal (β = 0·26, P = 0·001), itch (β = 0·26, P < 0·001) and depression (β = 0·24, P = 0·001) were the most robust predictors of poor sleep quality, which, together with somatic arousal (β = 0·17, P = 0·022), accounted for 43% of variance in PSQI scores.

CONCLUSIONS

Poor sleep is common in psoriasis and associated with psychological and physical factors. Rates of probable OSA are also high. Given the importance of restorative sleep for health, sleep complaints should receive greater clinical attention in the management of psoriasis.