Skin Conductance Levels May Reflect Emotional Blunting in Behavioral Variant Frontotemporal Dementia

Abstract

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.

Dominant hemisphere lateralization of cortical parasympathetic control as revealed by frontotemporal dementia

“…One study linked blunted phasic embarrassment-related, predominantly sympathetic autonomic responses to atrophy of the right pregenual ACC (68). Interestingly, baseline skin conductance level, a measure of sympathetic tone, was recently found to be reduced in patients with bvFTD (72), in contrast to the lack of a significant difference in our study (Table 1). Our experimental setting could have been insensitive to sympathetic deficits due to the calming influence of the scanner environment on healthy control subjects or an activating influence of the scanner on patients.…”

“…A recent study performed clinical autonomic function tests and reported a high prevalence of parasympathetic and sympathetic dysfunction in bvFTD without exploring the anatomical correlates of these deficits (13). In the context of emotion processing, several studies examined physiological reactivity to emotional stimuli and found that patients with bvFTD retained physiological responses to many stimuli (27,71,72) but that response amplitudes were diminished to emotional stimuli, such as those designed to elicit self-conscious emotions (71). One study linked blunted phasic embarrassment-related, predominantly sympathetic autonomic responses to atrophy of the right pregenual ACC (68).…”

Facial expressiveness and physiological arousal in frontotemporal dementia: Phenotypic clinical profiles and neural correlates

“…To date, few studies have employed psychophysiological techniques to objectively measure emotion processing in FTD, with mixed results. Some studies have reported attenuated skin conductance levels in response to aversive stimuli (loud noise) in bvFTD compared with Alzheimer's disease patients and healthy controls (Hoefer et al, 2008;Joshi et al, 2014). However, others have found no difference in physiological responses to complex emotional film stimuli between healthy controls and a mixed group of bvFTD and SD patients, despite impaired explicit emotion recognition performance in these syndromes (Werner et al, 2007).…”

Cardiac responses to viewing facial emotion differentiate frontotemporal dementias

“…9 If autonomic mechanisms contribute to aberrant emotion processing in FTD, one would anticipate associated changes in physiological reactivity, as has previously been documented in FTD syndromes. In particular, bvFTD has been associated with abnormal autonomic reactivity to affectively charged stimuli, [18][19][20][21][22] alterations of resting skin conductance and heart rate variability, 23,24 and abnormal brain-heart coupling, 24,25 while nfvPPA has been associated with reduced pupil responses to arousing stimuli. 20,26 Taken together, these findings are consistent with the known targeting of core cerebral autonomic fronto-cingulo-insular circuitry in bvFTD and nfvPPA.…”