Telephone-Based Behavioral Activation with Mental Imagery for Depression in Older Adults in Isolation During the covid-19 Pandemic: Long-term Results from a Pilot Trial

ABSTRACT Objectives The covid-19 pandemic has highlighted the need for psychological interventions for depression that can be delivered remotely to older adults. Pellas et al. (2022) conducted a pilot trial on the preliminary effectiveness of a four-week telephone-delivered Behavioral Activation with Mental Imagery (BA-MI) intervention to N= 38 adults 65 years and older with clinically significant depressive symptoms living in isolation due to covid-19 in Sweden. This study assessed the feasibility of follow-up assessments and within-group symptom change over a six-month post-intervention period. Methods Retention rates at post-intervention and follow-up assessments of depressive symptoms (MADRS-S) at five time points were assessed (baseline, post-intervention, 1-, 3-, and 6-month follow-up). Effect sizes (Hedges’ g) for within-group change scores were calculated between each time point. Results Retention rates over time were 95, 82, 89, and 84%. Mean MADRS-S score was 18.26 at baseline, 13.69 at post-intervention (g= .68), 13.42 at 1 month (g= .74), 13.82 at 3 months (g= .74), and 15.59 at 6 months (g= .41). Conclusions Long-term follow-ups were feasible. Within-group decreases in depressive symptoms were maintained with medium effect sizes at 6 months post-intervention. Clinical implications Telephone-based BA-MI may be a feasible intervention for depressive symptoms in older adults in isolation with maintained effects over time.

In the beginning of 2020, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causing the Coronavirus disease 2019 (covid-19) was classified as a pandemic.The virus carried a high mortality rate, particularly in adults aged 70 years or above.To prevent the spread of the virus, a strategy called social distancing was used in many countries, recommending people to limit close contact with others and to stay at home as much as possible.The pandemic increased the rates of depression in older adults (Tyler et al., 2021), highlighting the need for scalable psychological interventions for this age group.Ideally such interventions could be delivered remotely, via for example the Internet, videoconferencing, or telephone.While psychological treatment delivered by Internet and videoconferencing produce effects comparable to face-to-face psychotherapy (Egede et al., 2015;Xiang et al., 2020), there might be a barrier in some older adults related to the equipment and skills needed for these treatment modalities.
Telephone-delivered psychotherapy may be an option for these individuals, and indeed previous studies show promising results (Tutty, Spangler, Poppleton, Ludman, & Simon, 2010).To make the intervention scalable as a first-line treatment, it should also be time-efficient.Behavioral activation (BA) is a brief psychological treatment focusing on increasing engagement in adaptive activities and decreasing engagement in activities that maintain depression or increase risk for depression (Dimidjian, Barrera, Martell, Muñoz, & Lewinsohn, 2011), often by scheduling meaningful and enjoyable activities.BA is an effective treatment for depression in adults (Cuijpers, van Straten, & Warmerdam, 2007), and evidence suggests it is also effective in older adults (Orgeta, Brede, & Livingston, 2017).BA has been shown to be feasible in briefer formats, for example in four sessions (Funderburk, Pigeon, Shepardson, & Maisto, 2020;Funderburk et al., 2021).However, depression is often accompanied by a lack of energy and low motivation, which can make it difficult to engage in scheduled activities.Mental Imagery (MI) could be used as a "motivational amplifier" in combination with behavioral activation, to increase the likelihood of performing scheduled activities (Heise, Werthmann, Murphy, Tuschen-Caffier, & Renner, 2022;Ji, Geiles, & Saulsman, 2021;Renner, Murphy, Ji, Manly, & Holmes, 2019).MI is defined as a perceptual experience without external sensory input (Pearson, Naselaris, Holmes, & Kosslyn, 2015).Futuredirected imagery-based thought has been suggested to increase the anticipation of rewards and thereby increase behavior driven motivation to attain those rewards (Heise et al., 2022;Ji et al., 2021;Renner et al., 2021).
In 2020, the authors conducted a pilot randomized clinical trial (N = 41) testing the feasibility, acceptability and preliminary efficacy of a brief behavioral activation intervention augmented with mental imagery (BA-MI) for older adults with depression who were living in isolation due to the covid-19 pandemic restrictions (i.e.limit close contact with others and staying at home as much as possible) (Pellas, Renner, Ji, & Damberg, 2022).The BA-MI intervention was based on a four-session behavioral activation treatment (Funderburk et al., 2020(Funderburk et al., , 2021)), focusing on scheduling pleasant and meaningful activities, combined with a mental imagery (MI) intervention (Renner et al., 2019) in session two and three.In the MI intervention, the participants were requested to vividly imagine themselves performing one of their planned activities, focusing on emotionally positive aspects of activity engagement.The drop out-rate was low (7.3%).Most participants in the intervention group were satisfied with the treatment, and few adverse effects were observed.The intervention condition resulted in significant decrease in depressive symptoms compared to the control condition.At post-intervention, the number of depression diagnoses compared to baseline had decreased from 16 to 2 in the intervention condition and from 13 to 9 in the control condition.Although promising, questions remained about the feasibility of long-term follow-ups and intervention effects over time.
Drawing on the data of our pilot trial (Pellas et al., 2022), the aims of the present study are 1) to investigate the feasibility of long-term follow-ups at 1-, 3-, and 6-months post-intervention and 2) to assess depressive symptoms at 1-, 3-, and 6-months post-intervention.

Design
While the original study was a pilot randomized clinical trial (Pellas et al., 2022), the present study of long-term outcomes is an extension using a single-group pretest-posttest design, with participants from both the intervention condition that received the intervention directly and participants from the control condition that received the intervention after four weeks.The intervention was the four-week telephonedelivered BA-MI treatment (Pellas et al., 2022).
The intervention part of the trial was conducted consecutively between August and October 2020, with long-term follow-ups at 1-, 3 -and 6-months post-intervention.

Participants
Thirty-eight participants completed the study, of which 20 were in the intervention condition and 18 in the control condition receiving the identical intervention after four weeks, see Figure 1 for participant flow through the trial.Participants had a mean age of 75.39 years (SD 7.21).Out of the 38 participants, 32 (84%) were women.At baseline, 29 (76%) fulfilled diagnostic criteria for current major depressive episode.All participants were recruited from one county in Sweden and treated through the Adult Psychiatric Clinic at Västmanland County Hospital.The participants were recruited through advertisements in local newspapers and in primary care centers.The inclusion criteria were 1) 65 years or older, 2) clinically significant depressive symptoms on a depression rating scale and/or fulfilling criteria for major depressive episode on the Mini international neuropsychiatric interview (MINI) (Sheehan et al., 1998), 3) access to telephone, 4) fluent in written and spoken Swedish, 5) residing in the County of Västmanland.Exclusion criteria were severe depression, elevated suicide risk, current substance use disorder, current or previous manic or hypomanic episodes, current psychotic disorder, current diagnosis of major neurocognitive disorder, currently receiving psychological treatment, and currently receiving antidepressant medication that commenced less than one month ago.The study received ethical approval from the Swedish Ethical Review Authority (ID 2020-02079) and all participants provided written informed consent.The study was preregistered with ClinicalTrials.gov(ID NCT04508868).

Measures
Depressive symptoms were measured with the Montgomery-Åsberg Depression Rating Selfrating Scale, MADRS-S (Svanborg & Asberg, 1994).The MADRS-S is a nine-item questionnaire designed to measure depression severity during the past two weeks.The total score ranges from 0-54, with higher scores indicating higher depression severity.A score of 12 or less indicates no depression, 13-19 mild depression, and 20 or above moderate to severe depression (Svanborg & Ekselius, 2003).The MADRS-S was completed at baseline, post-intervention, and at follow-ups 1-, 3-, and 6-months postintervention.Full details of the materials are described in (Pellas et al., 2022).

Statistical analyses
To assess the preliminary long-term efficacy, the within-group effect size with Hedges' g correction was calculated on the MADRS-S between baseline and post-intervention and follow-ups at 1-, 3-, and 6-months post-intervention.The effect sizes were interpreted in line with recommendation for gerontological research (Brydges, 2019): 0.15 = small, 0.40 = medium, and 0.75 = large.All analyses were conducted using IBM SPSS Statistics version: 28.0.0.0.

Feasibility
Feasibility of the long-term assessments were recorded by the retention rate, i.e., the number of participants returning the rating scales at each follow-up.Out of 38 participants, 36 (95%) completed the post-intervention assessment, 31 (82%) completed the 1-month follow-up, 34 (89%) completed the 3 months follow-up, and 32 (84%) completed the 6-month follow-up.

Discussion
The covid-19 pandemic has highlighted the need for scalable psychological interventions for depression that can be delivered remotely.While the former analysis of a pilot-study on telephone-based BA-MI intervention indicated that the intervention was feasible, acceptable, and potentially effective in treating depressive symptoms in older adults during the covid-19 pandemic (Pellas et al., 2022), it was unclear whether the long-term follow-ups were feasible and whether effects were maintained in the long-term.In the present study, retention at postintervention and follow-ups 1-, 3-, and 6-months post-intervention was high, 95, 82, 89, and 84% respectively, demonstrating that the long-term follow-ups were feasible for at least 6 months.Depressive symptoms remained stable from postintervention to 1-and 3-months post-intervention but increased from post-intervention to 6 months post-intervention.The effect sizes were medium for all follow-ups compared to baseline, although with a lower effect size at 6 months (0.41) compared to post-intervention (0.68) and after 1 and 3 months (0.74 for both).These results indicate that the effects of the relatively short 4-week intervention are maintained over time for many of the participants, in line with previous studies on behavioral activation (Cuijpers et al., 2007).However, the effect sizes need to be interpreted with caution, as small sample sizes tend to inflate the effect size (Button et al., 2013).Further studies in larger samples are needed to investigate the long-term effects, for example if there is a general deterioration in mood after 6 months or if there are sub-groups with different trajectories.Long-term effects of this intervention should also be compared to control conditions.
There are several limitations to this study.First, even though the retention rates were high, the total sample was small, limiting the possibility for statistical analyses.Second, as this study included only participants that had received intervention and no control condition, it is not possible to ascertain how long-term results would be for participants not receiving intervention.This procedure was however necessary, as it would have been unethical to withhold the participants in the control condition from intervention as the control condition was only an attention control and not another active treatment.Third, as the participants were originally from two groups, an intervention condition (N = 20) and a control condition (N = 18) receiving the intervention after four weeks, there was a difference in the procedure, where 20 of the participants received a four-week intervention directly and 18 of the participants received four weeks of attention control followed by the fourweek intervention.This was accounted for by establishing a new baseline for the control condition before receiving the intervention.Fourth, the sample consisted of volunteers recruited via advertisements, limiting the generalizability to other groups or environments.Fifth, the majority of the participants (84%) were women, which might limit the generalizability of the results to older adults in general.
Moving further, studies in larger samples as well as studies in clinical environments are needed to evaluate the BA-MI intervention.It would also be of interest to investigate noninferiority compared to face-to-face intervention, as well as performing studies dismantling the effect of the behavioral activation and the mental imagery component.

Figure 1 .
Figure 1.Participant flow through the trial.

Figure 2 .
Figure 2. Mean depression severity on MADRS-S throughout the trial and effect sizes (Hedge's g) between baseline and subsequent measurement points.Error bars are standard deviations.

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The covid-19 pandemic has highlighted the need for scalable psychological interventions for depression that can be delivered remotely to older adults.• Behavioral activation with mental imagery reduced depressive symptoms in older adults in isolation during the covid-19 pandemic, with medium-sized effects for up to 6 months post intervention.• Behavioral activation with mental imagery may be a feasible intervention for depressive symptoms in older adults living in isolation due to the covid-19 pandemic, but full-scaled clinical trials are needed.