The content was based on prior interventions, considering the caregivers' active involvement, adapting to their specific needs, addressing multiple areas of need, sporadic interventions over the course of the care, and the priority-based adjustment of the intensity or approach. This structure was adopted in all the sessions: 1) Review of homework, 2) Theoretical content, 3) Practical application of theoretical content, 4) Assignment of homework, and 5) Queries (see Table S1 of the supplementary material). The intervention involves eight 90-minute sessions held on a weekly basis

In the sessions, caregivers share concerns and experiences with other group members, expressing feelings and fears. There is reciprocity, as they are listened to, but at the same time information is provided, ideas, strategies and skills are shared to face daily caregiving situations. The sessions are not structured, on the contrary, the topics are proposed and developed by the caregivers and the professional has only a moderating role. The intervention involves eight 90-minute sessions held on a weekly basis.

Caregivers were not subject to any intervention. They received the psychoeducational intervention once the study had ended.

The psychoeducational intervention has the aim of improving quality of life, problem-solving and social skills, leisure time, self-efficacy and social support of caregivers; and decreasing their depressive symptomology, dysfunctional thoughts, burden and stress. Both mediator and outcome variables will be contemplated.

It was assessed using the World Health Organization Quality of Life Assessment - AGE (WHOQOL-AGE). It contains 13 items in a Likert-type format with five options consisting of a combination of bipolar and unipolar responses. A higher score corresponds to a better quality of life

Use was made of the Perceived Stress Scale (PSS). It consists of 14 items which assesses the level of stress the subject has perceived over the past month (from 0 = never to 4 = very often). The higher the direct score recorded, the higher the level of perceived stress.

This was assessed through the Center for Epidemiologic Studies-Depression Scale (CES-D). It consists of 20 items which assess whether an individual has manifested any of the symptoms of depression during the preceding week (from 0 = rarely or never to 3 = mostly or all the time). A higher score corresponds to a greater depressive symptomology .

It was assessed using the Caregiver Burden Interview (CBI). It consists of 22 items which measures the extent to which caregivers perceive that their duties put a burden on their health, personal and social lives, finances, and emotional wellbeing (from 1 = never through to 5 = almost always). A higher score signals a greater burden.