Title: Behavioural Activation for Low mood in Multiple Sclerosis The study will be sponsored by the University of Lincoln, indemnity will be provided by U M Association Limited.

Depression is highly prevalent among people with Multiple Sclerosis (MS). More specifically, as the disease progresses, people are more likely to develop depression and there is limited evidence of suitable interventions in this group. There are few studies that investigate the most appropriate duration, delivery modality, or individual adaptations for therapy for people with secondary progressive Multiple Sclerosis. This is problematic because continued reduction in physical and cognitive ability, combined with greater incidence of depression, may make accessing and engaging in therapies difficult.

Behavioural activation is a technique used as a component of psychotherapy. Behavioural activation aims to reduce behaviours that maintain or exacerbate depression by promoting counteracting behaviours, using strategies such as activity monitoring and scheduling.

However, there is no research looking in-depth at the underlying processes. Therefore, this research aims to explore the feasibility and efficacy of behavioural activation by:

• Adapting an existing behavioural activation manual into five sessions, suitable for people with secondary progressive MS.
• Examining if behavioural activation is followed by phases of change that are considered to predict later therapeutic outcome and to determine whether behavioural activation accounts for changes observed.

Up to ten participants from Nottingham University Hospitals will be recruited. Participants will be briefed on the research aims and consent will be obtained before commencing the intervention. The project will follow a multiple baseline single-case experimental design. Participants will complete weekly outcome measures that aim to observe low mood, quality of life, and adherence to behavioural activation and alignment with individual's values. Following five to six contact sessions, participants will take part in a follow-up interview. Participants will then be debriefed.

The study aims will be achieved using a single centre, mixed-methods design, over two phases. The first phase will be the adaptation of an existing behavioural activation manual. The aims of the second phase will be achieved using a multiple single-case experimental design and change interview. The multiple single-case experimental design will use an AB design where each participant is their own control.

Participants will be recruited from the Nottingham University Hospitals Trust by the multiple sclerosis (MS) clinical care team, who will provide participants with the study advertisement. The initial approach will be from a member of the patient's usual care team (which may include the investigator), and information about the trial will be on display in the relevant areas. Participants can also self-refer, using information from study-related advertisements placed in the MS clinics, MS Society local branch newsletters and social media. The study aims to recruit up to ten participants. A convenience sampling technique will be used to recruit participants. Following the identification of potential participants, the intervention will be conducted by telephone, internet video-calling software, and face-to-face meetings at the participant's home.

The investigator or their nominee, e.g. from the research team or a member of the participant's usual care team, will inform the participant or their nominated representative (other individual or other body with appropriate jurisdiction), of all aspects pertaining to participation in the study.

Participants will receive a screening and information pack, containing a consent form, participant information sheet, and Hospital Anxiety and Depression Scale. A telephone call from the researcher will provide opportunity for further questions. If the participant does not meet the inclusion criterion, they will be excluded and provided with an information sheet for managing emotions.

It will be explained to the potential participant that entry into the trial is entirely voluntary and that their treatment and care will not be affected by their decision. It will also be explained that they can withdraw at any time, but attempts will be made to avoid this occurrence. In the event of their withdrawal it will be explained that their data collected so far may not be erased in accordance with the University's Research Privacy Notice and information given in the Participant Information Sheet and the investigators will seek consent to use the data in the final analyses where appropriate.

Following the interview, participants will be thanked for their time with a £20 Amazon voucher.

Study as experienced by the participant:

Following recruitment, participants will be sent instructions for installing video communication software (e.g., Skype). The researcher will contact the participant to complete pre-intervention measures and collect demographic and clinical information. Following the contact, participants will complete the baseline measure every-other-day to establish a baseline. Participants will complete measures using Qualtrics (a data management service).

A baseline will be established over two weeks for each participant in which no other contact or procedure will be introduced. The baseline will be considered stable (established) when the participant has recorded no less than three data points on the baseline measure that show no trend toward improvement. If stability has not been demonstrated, the baseline will be extended on a week-by-week basis, for a maximum of two weeks. If a stable baseline has not been established by the fourth week, the participant will exit the study and be provided with information about managing distress and accessing further support.

Intervention (Sessions will be audio recorded):

Treatment planning Participants will receive a single face-to-face session at their home, lasting at least one hour up to a maximum of two hours.

Psychoeducation and behavioural activation Participants will receive a single psychoeducation session, followed by three, fortnightly, behavioural activation sessions. In addition, participants will be offered an optional support session for troubleshooting. Sessions will last up to one hour and contact will be made using internet video software.

Treatment evaluation Participants will receive a review session lasting up to one hour, contact will be made using internet video software.

Post-intervention Participants will be contacted by a fellow Trainee Clinical Psychologist to take part in a 30-minute, one-to-one, audio recorded phone interview.

Follow up (Optional) Two months following the treatment evaluation session participants will complete the follow up measures.

Intervention sessions will be audio recorded and then evaluated by an independent researcher from within the sponsors' institution, such as an MSc student. Fidelity will be investigated using a set framework, to investigate alliance, and content delivery adherence. Should participant decline sessions being audio-recorded, fidelity will be checked via session notes.

Data analysis:

Visual analysis will be used to analyse data collected during the intervention. The analysis identifies any phase-related changes in process and outcome variables. The analysis will provide a visual representation of the covariation between process and outcome measures, to explore whether/how the intervention has a positive impact on mood, fatigue, and quality of life. Additionally, visual analysis will be supplemented with use of reliable and clinically significant change indices, to provide quantitative decision criteria for identifying the statistical robustness and practical importance of any visually-apparent shifts over time. A framework analysis will be used to analysis the responses to the change interview.

Inclusion Criteria:

• Clinical diagnosis of Secondary Progressive Multiple Sclerosis
• Must speak English
• Must have capacity to give consent
• Must have a telephone
• Must have access to the internet
• Must be able to use a computer
• Must score ≥ 8 on the Hospital Anxiety and Depression Scale - depression subscale

Exclusion Criteria:

• Receiving psychological therapy for a pre-existing mood problem.