The study design involves protocol refinement and clinical trial evaluation phases:

1. Refinement. The first phase of this proposal involves refining our existing protocol - "Combating Social Isolation" based on feedback from the target population (i.e., older adults experiencing loneliness). A small but representative sample of older adults (\> age 64) (diversified by race, gender, and SES) from the Tallahassee metropolitan area will review the intervention and provide feedback (N approximately 12). The existing protocol includes psychoeducation about healthy relationships, "myth busting" around cognitive errors associated with loneliness (largely focused on social interaction) as well as skill building for social relationships. During the refinement phase, input from our collaborator with expertise in the development and use of technologies in older adults (Dr. Boot) will be utilized in an attempt to ensure good acceptability across the sample. Input from our collaborators specializing in interventions for older adults (Drs. Sheffler and Van Orden) will also be incorporated prior to and following feedback from participants. Feedback regarding ease of use, comprehension, limitations, and suggestions will be solicited using semi-structured interviews. Based on these assessments, the treatment will be redesigned accordingly. This phase is expected to take approximately 2 months. Note that the investigators have completed similar refinements for this intervention as well as others for particular populations (e.g., active duty military, first responders, Latinx) including the translation to different cultures and countries (e.g., Mexico, Japan, Germany, Australia).
2. Randomized Clinical Trial (RCT). Following refinement, the investigators will initiate a RCT focused on indicated prevention of adverse sequelae resulting from elevated loneliness. The final phase of the proposal will be used to determine the relative efficacy of the refined intervention versus a health education control condition. The rationale for an indicated prevention RCT is that only a subset of older adults' experiences significant loneliness. The investigators believe that this is an optimal target for an initial clinical trial for this intervention. An alternative approach would be to conduct a universal prevention RCT using a nonselected group of older adults. While the investigators believe that many (perhaps most) individuals would benefit from the information and skills covered in CSI, a more focused clinical trial at this stage would offer a more efficient means of demonstrating efficacy in the subgroup of older adults most likely to benefit from this intervention. Outcomes will be compared at post-treatment and at a one-month follow-up. The main dependent variables of interest will include loneliness, quality of interpersonal relationships and internalizing symptoms (anxiety and depression). This phase is expected to last 10 months.

Design Considerations. As with any project, there are a broad array of design options that may yield relevant information. In this section, the investigators summarize some of the key issues that contributed to the proposed study design.

Protocol Modification. Given that the existing protocol shows efficacy, there is some risk in modifying it. Therefore, our approach will be similar to other refinement studies where the investigators keep the core skills covered but substitute specific content areas with more relevant information. As noted above, the unique features of aging relevant to loneliness need to be incorporated (e.g., death of spouse, close friends, loss of independence). For example, one version of CSI includes vignettes and descriptions of active duty soldiers and Veterans that are unlikely to be relevant to many older adults. This content would be removed and replaced with vignettes featuring older adults with content that is appropriate and more typical for older adults.

Using a Semi-active Control Condition in the RCT. There are many different RCT designs that could be utilized including a waitlist control, which is likely to yield a larger effect size difference with the active intervention. However, prior studies suggest that CSI can outperform the proposed control condition, and this control condition helps to account for many confounds that a waitlist does not. Therefore, the investigators believe our choice of a stronger control group is warranted. Our "Healthy Lifestyle" control condition is also a web-based protocol that covers information and skills that many people believe to be helpful. Moreover, most participants find this control condition to be useful.

Limited Follow-up. Having a follow-up is important to demonstrate the initiation as well as some durability of treatment effects since the investigators would not expect immediate (post treatment) change in the outcomes of interest. As with any skill building protocol, time is needed for skills to be implemented. On the other hand, the duration of the grant period (12 months) limits the length of a viable follow-up period. The investigators believe that a one-month follow-up will be sufficient to show whether there are any treatment effects. Additional studies will be needed to demonstrate longer term benefits of the intervention.