Nature On Prescription to Support Mental Ill Health (GREENGAGE): A Pilot Randomised Controlled Trial and Process Evaluation

Research question This external randomised pilot trial will test and finalise the processes for undertaking a definitive randomised controlled trial (RCT) to assess the effectiveness and cost-effectiveness of a group, nature-based intervention in addition to usual care, versus usual care alone, for adults with mild to moderate depression and/or anxiety.

Background Common mental health conditions, such as depression, anxiety, and stress, affect up to 15% of the UK population at any time, and one in four people experience a mental health problem at some point in their lives.

The shift towards personalised care for people with mental ill health includes facilitating access to community-based sources of support.

Pathways such as social prescribing (SP) link people to social or community-based resources – including nature-based activities – which have the potential to improve health and wellbeing.

While there are numerous organisations in the UK providing nature-based activities, there are few studies using the most reliable methods to assess their effectiveness for people with mental ill-health.

Aims and Objectives We aim to test and finalise the processes for undertaking a definitive, fully-powered RCT of the effectiveness and cost-effectiveness of a nature-based intervention in addition to usual care versus usual care alone (wait-list control group) for adults with mild to moderate depression and/or anxiety.

Methods This is an external pilot RCT of nature-based activities for people with mild to moderate depression and/or anxiety.

We aim to recruit 84 people via GPs, community groups and social media advertising who will be randomised to receive either a 6-week nature-based activity course at one of three locations in the south west of England, together with usual care, or receive usual care alone. Randomisation will be stratified by location.

We will collect data on participants mental health and well being using the Office of National Statistics “Personal Wellbeing” Domain (ONS4); the short version of the Warwick–Edinburgh Mental Wellbeing Scale (sWEMWBS) Patient Health Questionnaire- (PHQ-9) and General Anxiety Disorder measure ()GAD-7, and a loneliness scale prior to the randomisation and at two later time points (at 6 and 12 weeks after intervention start, approx. 8 and 16 weeks post-randomisation).

Data will be collected online. Health service use data will also be collected.

We will use decliner and participant surveys to understand factors that affect participation and focus group discussions to understand the experiences of those participating in the pilot to help refine the process for the future trial. Timelines for delivery 18 months.

October 2024-March 2026 Anticipated Impact and Dissemination A key outcome will be the development of a detailed protocol for a future definitive RCT of nature-based activities for people with mild to moderate depression and/or anxiety.

In addition, we will write up the results of the pilot study for publication in an open access journal, and produce a plain language summary to be shared with participants, members of the public and other stakeholders.