Caregiver burden is greater in frontotemporal dementia (FTD) than in Alzheimer disease (AD). However, little is known of the impact of the 3 main clinical variants of FTD- behavioral-variant frontotemporal dementia (bvFTD), semantic dementia (SemDem), and progressive nonfluent aphasia (PNFA)-or the role of disease severity in caregiver burden. The Zarit Burden Inventory was used to measure caregiver burden of bvFTD (n=17), SemDem (n=20), PNFA (n=20), and AD (n=19) patients. Symptom duration, caregiver age, and relationship type were matched across groups. Moreover, a number of caregiver (mood, social network) and patient variables (functional disability, behavioral changes, relationship with caregiver, and dementia stage) were addressed to investigate their impact on caregiver burden. Caregivers of bvFTD patients reported the highest burden, whereas SemDem and PNFA caregivers reported burden similar to AD. A regression analysis revealed that caregiver burden in FTD, regardless of subtype, was explained by a model combining disease staging, relationship changes, and caregiver depression. Burden increased with disease severity in FTD. This study is the first to show that caregivers of SemDem, PNFA, and AD patients show similar burden, while confirming that bvFTD caregivers show higher burden than AD caregivers. More importantly, this study demonstrates that burden worsens with disease progression in FTD.