Electrodermal lability in anxiety disorders

A Systematic Review of Thermosensation and Thermoregulation in Anxiety Disorders

Objectives: Sweating, hot flushes, and blushing are symptoms frequently reported by individuals with anxiety disorders. They represent important reinforcers of anxiogenic cognitions and behaviours. One system that may be involved in the manifestation of these symptoms is the thermosensory/thermoregulatory system. The aim of the present study was to investigate to what extent individuals with anxiety disorders are characterised by alterations in this system.

Methods: PubMed and PsycINFO were systematically searched. Studies were eligible if they (i) assessed individuals with anxiety disorders, (ii) thermosensation or thermoregulatory effectors/outcomes, and (iii) used a case-control design.

Results:N = 86 studies were identified. There was no evidence of altered thermosensation in individuals with anxiety disorders. Regarding thermoregulatory effectors, individuals with social anxiety disorder exhibited altered cutaneous vasodilation upon pharmacological challenge; individuals with specific phobia showed increased sweating upon confrontation with phobic stimuli; individuals with panic disorder showed increased daily sweating as well as increased sweating in response to non-phobic and phobic stimuli. Regarding thermoregulatory outcomes, there was evidence for altered skin temperature in all subtypes of anxiety.

Conclusion: Whereas there was no evidence of altered thermoregulation in specific phobia, a subgroup of individuals with social anxiety and panic disorder appears to exhibit altered vasodilation and sweating, respectively. Longitudinal research is warranted to investigate whether this represents a vulnerability to anxiety/panic.

Depersonalization disorder: disconnection of cognitive evaluation from autonomic responses to emotional stimuli

BACKGROUND

Patients with depersonalization disorder (DPD) typically complain about emotional detachment. Previous studies found reduced autonomic responsiveness to emotional stimuli for DPD patients as compared to patients with anxiety disorders. We aimed to investigate autonomic responsiveness to emotional auditory stimuli of DPD patients as compared to patient controls. Furthermore, we examined the modulatory effect of mindful breathing on these responses as well as on depersonalization intensity.

METHODS

22 DPD patients and 15 patient controls balanced for severity of depression and anxiety, age, sex and education, were compared regarding 1) electrodermal and heart rate data during a resting period, and 2) autonomic responses and cognitive appraisal of standardized acoustic affective stimuli in two conditions (normal listening and mindful breathing).

RESULTS

DPD patients rated the emotional sounds as significantly more neutral as compared to patient controls and standardized norm ratings. At the same time, however, they responded more strongly to acoustic emotional stimuli and their electrodermal response pattern was more modulated by valence and arousal as compared to patient controls. Mindful breathing reduced severity of depersonalization in DPD patients and increased the arousal modulation of electrodermal responses in the whole sample. Finally, DPD patients showed an increased electrodermal lability in the rest period as compared to patient controls.

CONCLUSIONS

These findings demonstrated that the cognitive evaluation of emotional sounds in DPD patients is disconnected from their autonomic responses to those emotional stimuli. The increased electrodermal lability in DPD may reflect increased introversion and cognitive control of emotional impulses. The findings have important psychotherapeutic implications.

Psychophysiological investigations in depersonalization disorder and effects of electrodermal biofeedback

Previous studies investigating depersonalization disorder (DPD) report a lower baseline skin conductance level (SCL) and attenuated skin conductance response (SCR) to emotive stimuli. We hypothesized that increasing physiological arousal levels via electrodermal biofeedback may ameliorate disembodiment and emotional numbing symptomatology. Real-time versus sham biofeedback yielded a significant SCL increase after just 3 real-time biofeedback sessions in healthy volunteers. Subsequently, a randomized controlled biofeedback trial was administered with DPD patients. Findings were not replicated as SCL tended to fall, curiously more substantially in the real-time condition, concomitant with increased low- and high-frequency heart rate variability. To further investigate abnormal autonomic regulation in DPD, we compared basal autonomic activity between patients and healthy volunteers and found the former to be significantly more labile, indexed by greater nonspecific SCRs and higher resting SCLs. Rather than low sympathetic arousal, DPD might be better characterized by abnormal autonomic regulation affecting emotional and physiological responsivity.

Physiological and behavioral differences in sensory processing: a comparison of children with autism spectrum disorder and sensory modulation disorder

A high incidence of sensory processing difficulties exists in children with Autism Spectrum Disorder (ASD) and children with Sensory Modulation Disorder (SMD). This is the first study to directly compare and contrast these clinical disorders. Sympathetic nervous system markers of arousal and reactivity were utilized in a laboratory paradigm that administered a series of sensory challenges across five sensory domains. The Short Sensory Profile, a standardized parent-report measure, provided a measure of sensory-related behaviors. Physiological arousal and sensory reactivity were lower in children with ASD whereas reactivity after each sensory stimulus was higher in SMD, particularly to the first stimulus in each sensory domain. Both clinical groups had significantly more sensory-related behaviors than typically developing children, with contrasting profiles. The ASD group had more taste/smell sensitivity and sensory under-responsivity while the SMD group had more atypical sensory seeking behavior. This study provides preliminary evidence distinguishing sympathetic nervous system functions and sensory-related behaviors in Autism Spectrum Disorder and Sensory Modulation Disorder. Differentiating the physiology and sensory symptoms in clinical groups is essential to the provision of appropriate interventions.

Personality and electrodermal response lability: an interpretation

Electrodermal response (EDR) lability is a psychophysiological trait reflecting stable individual differences in electrodermal activation as indexed by frequency measures of phasic EDR activity. There is no consistent evidence that EDR lability reflects dispositional or clinical anxiety. However, EDR lability appears to be related to individual differences in the overt expression of emotional and antagonistic impulses. Greater EDR lability is associated with a relatively undemonstrative and agreeable disposition, whereas greater EDR stability is associated with a relatively expressive and antagonistic disposition. The inverse relationship between EDR lability and the expression of emotional and antagonistic impulses suggests that EDR lability may reflect individual differences in the effortful control of such expression. This hypothesis is consistent with cognitive effort interpretations of phasic EDR activity, with evidence of the sensitivity of phasic EDR activity to capacity-demanding tasks, and with evidence of reduced spare capacity among EDR labile individuals under cognitive challenge. Individual differences in effortful self-control may explain the association of greater EDR lability with essential hypertension and greater EDR stability with forms of antisocial behavior.

Personality correlates of startle habituation

This study investigated the relationship between extraversion and rates of acoustic startle habituation, a potential biological marker for individual differences. Personality was measured using the Eysenck Personality Questionnaire (EPQ), the Sensation Seeking Scale (SSS), and Tellegen's Multidimensional Personality Questionnaire (MPQ). Higher EPQ Extraversion and higher SSS scores were associated with faster, more rapid startle habituation. Moreover, the relationship between extraversion and faster startle habituation was replicated in a second, follow-up sample. Within the initial study sample, lower scores on the Constraint (CON) factor of the MPQ (reflecting greater impulsiveness, risk-taking, and nonconformity) were also associated with faster startle habituation. Follow-up analyses revealed relationships between EPQ Extraversion, SSS, and low MPQ CON. These results suggest that faster habituation within the CNS may be associated tendencies toward impulsivity and behavioral disinhibition.

Associations between EEG asymmetries and electrodermal lability in low vs. high depressive and anxious normal individuals

In order to investigate one aspect of cortical-autonomic control, cortical activation asymmetries, measured by EEG, were related to activity of the sympathetic nervous system, measured by EDA (electrodermal lability, number of spontaneous fluctuations), in two large samples. Since it may help to explain the participation of psychological factors in the development of various somatic complaints and disorders, we examined whether inter-individual differences in autonomic nervous system regulation may exist that are related to stress/anxiety and depression within the normal range. Results demonstrate substantial modifications of functional hemisphere asymmetries in the modulation of EDA by these emotional factors and suggest that activation asymmetries in orbital and dorsolateral frontal regions reflect two different cortical sub-systems regulating electrodermal activity. The findings may, to some extent, provide an explanation for contradictory results in previous studies and may encourage research in psychosomatics and other clinical fields (e.g. schizophrenia).

Perceptual reactance, drug preference, and electrodermal activity in treatment-seeking substance abusers

Perceptual reactance (PR) was explored as a contributing variable to drug abuse. PR is defined as the general tendency of an individual's central nervous system to perceptually modulate incoming sensory stimuli. Using an adaptive model of drug use, it was hypothesized that drug preference in substance abusers would vary with PR. Specifically, perceptual reducers, who subjectively dampen afferent sensation, would prefer experience-expanding drugs (i.e., cocaine and amphetamines) to heighten perception. Conversely, perceptual augmenters would prefer sensory-restricting drugs (i.e., opioids and sedative-hypnotics) that attenuate or modulate environmental stimuli. Utilizing subjective (Reducing-Augmenting Scale) and objective (electrodermal responses) measures of PR, the relationship was tested in a sample of treatment-seeking substance abusers (n = 122). The sample was stratified on whether or not they were abstinent. Interestingly, a higher than anticipated rate of electrodermal non-responsivity was found across the sample and the implications of this finding are discussed. The study hypothesis was only supported in the electrodermally-responsive group.