Objectives The aims of the study were to identify the clinical characteristics of three groups of caregivers: spouses, live‐in adult–child or non‐live‐in adult–child, and their relation to the degree of perceived burden (Caregiver Burden Interview). Methods The sample comprised 275 Alzheimer's disease primary caregivers, with a follow‐up of 24 months. Cognitive, functional and behavioural characteristics were evaluated in persons with dementia, whilst sociodemographic data, use of socio‐medical resources, physical and mental health and self‐perceived burden were assessed in caregivers. Generalized estimating equations were used for longitudinal data analysis. Results Spouse caregivers were 45.0% men, sole caregivers (>80%), used few external resources and had worse physical health. The number of female adult–child caregivers was higher (>75%). The live‐in adult–child group, compared with the non‐live‐in adult–child group, was less likely to be married, had a lower level of education, was more commonly the sole caregiver and used fewer external resources. The greatest burden was observed in live‐in adult–child caregivers, and the lowest in the non‐live‐in adult–child group, with no significant variation in the follow‐up for both groups. Spouses had an intermediate level of perceived burden, which rose significantly during follow‐up (p < 0.001). Conclusions Kinship and cohabitation with the persons with dementia were associated with different scores and evolution of the burden, with an increase in the follow‐up of the spouses, and with more or less burden, depending on cohabitation, in the adult–child groups. Interventions to reduce the level of burden on caregivers should consider these differences. Copyright © 2017 John Wiley & Sons, Ltd.