The Mentis Plus+ Caregivers programme is an adaptation of the Mentis Plus+ intervention for informal caregivers of people with dementia. The original Mentis Plus+ programme was developed based on the Multifactorial Model of Positive Mental Health.

The intervention will last 7 weeks (one session per week, each lasting approximately 1 hour) and may be delivered individually or in groups of 2 to 12 participants. It will consist of two initial sessions, followed by three sessions focused on the selected factor. In addition, a final session and a follow-up session (3 to 6 months after programme completion) will be conducted.

Participants allocated to the control group will be informed that they will remain on a waiting list for a minimum of 3 to 6 months before receiving the Mentis Plus+ programme. Given the preventive nature of this study, the use of a waiting list control group is not expected to pose any risks or harm to participants.

Mentis Plus+Caregivers is a positive mental health promotion programme for informal caregivers of people with dementia. It is organised into six modules: (F1) Personal Satisfaction; (F2) Prosocial Attitude; (F3) Self-control; (F4) Autonomy; (F5) Problem-solving and Self-actualisation; and (F6) Interpersonal Relationship Skills. Each module is delivered through three sequential sessions (A, B and C). The identification of target module is based on the results of the Positive Mental Health Questionnaire "low-scoring or declining" . In addition to the modular sessions, the programme includes two initial sessions, an introductory session (group or individual) and a first individual session, and two final sessions, consisting of a final assessment session and an individual follow-up session conducted between 3 and 6 months after programme completion. Participants are grouped according to the same module to be addressed.

This instrument consists of 39 items that assess thoughts, feelings, and behaviours, grounded in the multifactorial model of Positive Mental Health and its six key factors. The participants were invited to select the frequency option they most identified with, presented on a 4-point Likert scale (1 to 4): "always or almost always" (1), "most of the time" (2), "sometimes" (3), and "rarely or never" (4). This instrument makes it possible to calculate the level of positive mental health for each factor, allowing the identification of which factor, or factors, requires intervention. The score ranges from 39 to 156, with the possibility of categorizing into different levels depending on the results, namely low or languishing (39 to 78), intermediate (79 to 117), high or flourishing (118 to 156), with a higher score representing higher level of Positive Mental Health.

This instrument consists of 39 items that assess thoughts, feelings, and behaviours, grounded in the multifactorial model of Positive Mental Health and its six key factors. The participants were invited to select the frequency option they most identified with, presented on a 4-point Likert scale (1 to 4): "always or almost always" (1), "most of the time" (2), "sometimes" (3), and "rarely or never" (4). This instrument makes it possible to calculate the level of positive mental health for each factor, allowing the identification of which factor, or factors, requires intervention. The score ranges from 39 to 156, with the possibility of categorizing into different levels depending on the results, namely low or languishing (39 to 78), intermediate (79 to 117), high or flourishing (118 to 156), with a higher score representing higher level of Positive Mental Health.

This instrument consists of 39 items that assess thoughts, feelings, and behaviours, grounded in the multifactorial model of Positive Mental Health and its six key factors. The participants were invited to select the frequency option they most identified with, presented on a 4-point Likert scale (1 to 4): "always or almost always" (1), "most of the time" (2), "sometimes" (3), and "rarely or never" (4). This instrument makes it possible to calculate the level of positive mental health for each factor, allowing the identification of which factor, or factors, requires intervention. The score ranges from 39 to 156, with the possibility of categorizing into different levels depending on the results, namely low or languishing (39 to 78), intermediate (79 to 117), high or flourishing (118 to 156), with a higher score representing higher level of Positive Mental Health.

The Depression Anxiety Stress Scale with 21 items (DASS-21) is the short version of the original DASS, which is composed of 42 items. This self-reported tool represents a three-part model that assesses emotional states with three subscales: depression, anxiety, and stress. The participants are invited to assess each statement with a 4-point Likert scale (0 to 3), from (0) = "nothing applied to me" to (3) = "applied to me most of the time", indicating the extent to which they experienced each symptom in the last week. The scale provides three scores, one per subscale, ranging from 0 to a maximum of 21. Higher scores represent more negative affective states