Depression affects between 5-15% of adults ≥ 65 years in Sweden. Depression in older adults reduces functional ability and quality of life, and increases the risk for morbidity, loneliness, and suicide. Psychological treatment is recommended as a first-line treatment for depression, which about 3% of older adults with depression in Sweden report receiving. One effective psychological treatment is behavioral activation, which reduces depressive symptoms by increasing enjoyable, meaningful and important activities, for example exercise and social activities. The research group conducted a pilot study of telephone based behavioral activation for isolated older adults with depression during the COVID-19 pandemic. The intervention consisted of four telephone calls, and the results showed a significant decrease in depressive symptoms, with maintained effects for six months.

250 individuals will participate in the study. Half of the participants will be randomised to start the intervention immediately, while the other half of the participants will be randomized to a control group receiving treatment as usual at their respective primary care center. Participants will be asked to fill in questionnaires before, after treatment. Questionnaires will also be sent 3- and 6 months after treatment to follow up on the results. Patients will be asked to wear an accelerometer for 5-7 days to record their activity level at baseline, post-intervention and after 3-months. A smaller group of participants (10-15) will be asked to participate in a more detailed interview about how they experienced the treatment.

In Sweden, depression among the elderly is a major public health concern. Major depression occurred in 5-15 % of the older population in Sweden, and one third of the women and a fifth of the men 65 years and older reported subclinical depressive symptoms. Several mental health experts raise concerns that there will be an increase of psychiatric illness during and after COVID-19, particularly among the elderly.

Depression in older individuals can be treated with antidepressant medication, psychological interventions and physical activity. However, the majority of the older individuals state that they would prefer psychological treatments to medication, which poses a challenge during COVID-19 as such treatments are often delivered face-to-face. Psychological treatments delivered via the Internet are as efficacious as face-to-face, but only 3-4% of the individuals 65 years and above in Sweden use digital applications that replace physical healthcare visits.

The purpose of this randomised controlled multicenter study is to evaluate the effects and outcomes of a telephone-delivered Behavioral Activation-treatment for older adults with depression in primary care within the framework of the research project DepActive. Our study specifically aims to: 1. investigate the effect of a telephone-delivered BA-treatment for older adults with depression in primary care with regards to a. depressive symptoms (primary outcome measure) b. depression diagnosis c. anxiety symptoms d. quality of life e. activity level f. functional ability g. cognitive function h. loneliness i. self-efficacy j. cost effectiveness k. care consumption including pharmacological treatment 2. explore patients' and therapists' experiences of the treatment 3. investigate to which extent the BA-treatment corresponds to person-centered care 4. investigate the mediating role of type of activity and level of physical activity with regards to improvement in depressive symptoms 5. investigate whether the intervention impacts the need for community healthcare services for participants utilizing such services.

The study is a multi-center randomised controlled clinical trial in primary care in the Swedish county councils of Vastmanland, Uppsala and Sormland.

Participants will be recruited from multiple primary care centers in each region. If the participant is enrolled in the study, the study therapist performs the randomisation by using an online randomisation software with a 1:1, random-blocks sequence. The participants are randomised consecutively to two arms: control group or intervention group. The control group will receive treatment as usual (TAU) in primary care, and the intervention group will receive TAU with the addition of a five-session telephone-based BA-intervention over an eight-week period.

Inclusion Criteria:

• Participants should fulfill criteria for current major depressive episode or sub-threshold depressive episode.
• Eligible participants should be 65 years or older, should be fluent in spoken and written Swedish to understand the treatment materials, have access to telephone, and be interested in participating in the trial.

Exclusion Criteria:

• Severe depression, elevated suicide risk, current substance use disorder, current or previous manic or hypomanic episodes, current psychotic disorder, and current diagnosis of minor or major neurocognitive disorder or suspected neurocognitive disorder with < 24 points on the Mini Mental State Examination number 3, MMSE-NR3.
• ongoing psychotherapy