Loneliness-feeling socially isolated-is a stressor that is associated with chronic pain. The investigators will first conduct a small trial of Cognitive Behavioral Therapy for Loneliness (CBT-L)in Veterans with chronic pain reporting loneliness. After completing this small trial, the investigators will randomize-like a flip of a coin-a total of 40 participants to receive either CBT-L or CBT for Chronic Pain. The investigators will assess loneliness, the quality and quantity of social interactions, and pain outcomes such as pain-related interference, and thinking the worst about one's pain at baseline and after the treatment period. The investigators will also track participant flow, therapist adherence to the manual, participant homework completion, and participant satisfaction with the treatment.

Loneliness-a subjective emotional state characterized by the perception of social isolation-is a psychosocial stressor that is associated with increased mortality and chronic pain. Individuals who have chronic pain and report loneliness experience greater pain-related interference in activities, depression, and suicidal ideation. Importantly, there are potentially effective interventions that can be used to decrease loneliness; however, there are no studies that have directly intervened on loneliness among Veterans with chronic pain. Cognitive-Behavioral Therapy for Loneliness (CBT-L) intervenes on loneliness by addressing negative beliefs that perpetuate loneliness, increase negative affect, and reduce one's ability to engage in social activities. For a Veteran with chronic pain, this is critical as addressing negative affect, and having a sense that one has social support and engages social support are key aspects of increasing functioning. While CBT for Chronic Pain (CBT-CP) comprises skills to promote social functioning, more robust efforts may be needed to better address lonely while also addressing functional impairment.

The proposed two-year study uses a novel application of a brief, phone-delivered, evidence-based intervention, CBT-L, to decrease loneliness by modifying socially-relevant maladaptive thinking patterns, increasing engagement in enjoyable and social activities, and improving problem solving skills. Participants will be recruited nationally using online advertising. The objectives of the current proposal are to adapt CBT-L to optimize its impact on Veterans with chronic pain, examine if the recruitment, retention, and treatment delivery is feasible and if CBT-L is acceptable to participants, and assess parameters of key outcomes among participants randomized to receive CBT-L versus CBT-CP to inform a subsequent larger clinical trial.

To achieve these objectives, the investigators will adapt a manual through an evidence-based, iterative process then conduct one-arm trial of CBT-L (n=8) in Veterans with chronic pain reporting loneliness. After refining the manual and procedures following the one-arm trial, the investigators will randomize a total of 40 participants to receive either CBT-L or CBT-CP. The investigators will assess loneliness, the quality and quantity of social interactions, and pain outcomes such as pain-related interference, and pain catastrophizing at baseline and after the treatment period. The investigators will also track participant flow, therapist adherence to the manual, participant homework completion and participant satisfaction with the treatment.

Inclusion Criteria:

• Are English-speaking
• Are 18 years of age or older
• Have access to a phone or computer
• Report pain that occurs on at least half the days for six months or more
• Score at least 4 (of 10) on each of the three items on the PEG (Pain intensity, and Pain interference in Enjoying activities and General activities)
• Screen positive for loneliness by scoring at least a T-score > 60 on the NIH Toolbox loneliness scale

Exclusion Criteria:

• Do not understand informed consent
• Had a recent or have an upcoming surgery
• Have significant unstable or uncontrolled medical conditions, including cancer requiring ongoing oncology treatment
• Active severe substance use disorder

Two participants in the CBT for Loneliness arm were consented, but did not complete the baseline assessment. The other participant withdrew.

from enrollment until end of follow-up (baseline assessment, post-treatment assessment, 1-month follow-up; 8 intervention session; ~3 months)

The outcomes assessors will not know what condition that the participant was allocated to, nor will the statistician who is one of the co-investigators.