Emotional blunting is a core diagnostic feature of behavioral variant frontotemporal dementia (bvFTD). The authors evaluated skin conductance as a measure of emotional blunting among 10 patients with bvFTD compared with 10 with Alzheimer's disease and 14 healthy control subjects. Despite responses to an auditory startle stimulus, skin conductance levels (SCLs) were lower in the patients with bvFTD compared with the other groups. The low SCLs significantly correlated with ratings of emotional blunting. The authors conclude that low SCLs in bvFTD indicate a low resting sympathetic state and low emotional arousal. The measurement of SCLs may be a useful noninvasive diagnostic test for bvFTD.