Objective: The aim of the present work was to study the serial multiple mediating role of optimism, perceived social support and subjective burden in the relationship between objective burden and psychological distress in caregivers of people with Alzheimer´s Disease (AD). Method: One hundred and forty family caregivers of people living with AD were recruited from randomly selected Alzheimer Association Centres. They answered the General Health Questionnaire (GHQ), the Life Orientation Test-Revised (LOT-R), the Functional Social Support Questionnaire (DUKE.UNC), the Zarit Burden Interview (ZBI) and questions relating to gender, age and the amount of time spent on daily caregiving. Results: Results indicated that objective burden and subjective burden were both high in these caregivers. Optimism mediated on psychological distress through social support and through subjective burden with a full mediation role. When comparisons between indirect effects were performed, optimism was the mediator with the greatest effect between objective burden and psychological distress. Conclusion: This study highlights the indirect role of optimism and the advantages that interventions in optimism training in the early stages of the person with AD could produce. Thus, alleviating subjective burden and increasing perceived social support, which would lead to an improvement in the mental health of family caregivers of people with AD.