Liu et al. (Reference Liu2017) investigated caregiver burden of patients with frontotemporal lobar degeneration (FTD) and dementia with Lewy bodies (DLB), which was compared with caregivers of patients with Alzheimer's disease. The authors concluded that the frequency and severity of behavioral disturbances in caregiver of patients with FTD and DLB were higher than those with caregivers of patients with Alzheimer's disease. I have some concerns about their study.

First, Bonanni et al. (Reference Bonanni2017) reported that the prevalence of DLB in comparison with those of Alzheimer's disease and FTD was 24.5% and 57.5%, respectively, in primary centers. Liu et al. (Reference Liu2017) handled 36 patients with DLB, 325 patients with Alzheimer's disease, and 131 patients with FTD, and the corresponding percentage was 11.1% and 27.5%, respectively. Although direct comparisons between data from a single center and from multicenter should be paid with caution, the prevalence of dementia and its subtype would be differed according to several factors of the target population. The number of samples in patients with DLB was relatively small, and summing-up the number of patients with DLB and also FTD would lead to higher statistical power.

Second, Cheng and Lam (Reference Cheng and Lam2017) recently reported a difficulty of differential diagnosis for each type of dementia. Progression or severity in each type of dementia differs and appropriate adjustment is needed for the risk assessment of caregiver burden in patients with dementia. The clinical manifestations in each type of dementia would cause the frequency and severity of caregiver burden (Uflacker et al., Reference Uflacker, Edmondson, Onyike and Appleby2016). Liu et al. (Reference Liu2017) conducted a cross-sectional study, and I suppose that a follow-up study would clarify the change of caregiver burden with the progression of disease.

Finally, caregivers are fundamentally classified into family members and commercial staffing. I understand that Liu et al. (Reference Liu2017) handled caregiver burden in family carers and the authors partly traced the past report (Svendsboe et al., Reference Svendsboe2016). As a further study, risk assessment of caregiver burden in patients with dementia should be conducted with special reference to the type of caregivers.