Specific phobias

Hear it, fear it: Fear generalizes from conditioned pictures to semantically related sounds

Fear generalization is thought to be an important mechanism in the acquisition and maintenance of anxiety disorders. Previous studies have investigated fear generalization within one sensory modality - mainly within the visual domain. However, a growing body of evidence shows that emotional information is processed in more than one sensory modality. Based on network theories, we expected that fear may also generalize from stimuli in one sensory modality to another. To test our hypothesis, 42 participants underwent a differential conditioning paradigm, during which pictures were either presented with (vCS+) or without (vCS-) an aversive electric stimulus. After the acquisition phase, generalization was tested in the crossmodal group (n = 21) by presenting sounds which were semantically congruent to the visual vCS+ (i.e., the aGS+) or the vCS- (i.e., the aGS-). As a control, the unimodal group (n = 21) saw the pictures again. For the crossmodal group, we could show that US expectancy ratings generalized from conditioned pictures (vCS+) to semantically related sounds (aGS+). Moreover, when the vCS+ was presented during extinction, fear of the aGS+ extinguished, whereas extinction training with the aGS+ was found to be less effective for the vCS+. The findings are relevant for crossmodal fear acquisition and exposure therapy.

Stress, glucocorticoids and memory: implications for treating fear-related disorders

Glucocorticoid stress hormones are crucially involved in modulating mnemonic processing of emotionally arousing experiences. They enhance the consolidation of new memories, including those that extinguish older memories, but impair the retrieval of information stored in long-term memory. As strong aversive memories lie at the core of several fear-related disorders, including post-traumatic stress disorder and phobias, the memory-modulating properties of glucocorticoids have recently become of considerable translational interest. Clinical trials have provided the first evidence that glucocorticoid-based pharmacotherapies aimed at attenuating aversive memories might be helpful in the treatment of fear-related disorders. Here, we review important advances in the understanding of how glucocorticoids mediate stress effects on memory processes, and discuss the translational potential of these new conceptual insights.

Differentiating the subtypes of social anxiety disorder

Since the inclusion of subtypes of social anxiety disorder (SAD) in the DSM-III-R, the most studied have been generalized versus specific subtypes. Previous research indicated that the generalized subtype was associated with greater severity, comorbidity and functional impairment compared to the specific subtype, but more recent evidence supports a dimensional conceptualization of SAD. Earlier studies also possessed limitations, such as heterogeneity in definitions of generalized SAD. Based on the more recent findings and the limitations of the earlier studies, the DSM-5 eliminated the generalized specifier. However, it also retained a categorical system by including a performance-based fear specifier, thus leaving an open debate on whether or not a dimensional or categorical system best describes SAD. Future research could examine other, more recent concepts as potential subtypes (e.g., attentional biases), or perhaps the larger question of the overall utility in subtyping SAD.

Lifetime co-morbidity of DSM-IV disorders in the US National Comorbidity Survey Replication Adolescent Supplement (NCS-A)

BACKGROUND

Research on the structure of co-morbidity among common mental disorders has largely focused on current prevalence rather than on the development of co-morbidity. This report presents preliminary results of the latter type of analysis based on the US National Comorbidity Survey Replication Adolescent Supplement (NCS-A).

METHOD

A national survey was carried out of adolescent mental disorders. DSM-IV diagnoses were based on the Composite International Diagnostic Interview (CIDI) administered to adolescents and questionnaires self-administered to parents. Factor analysis examined co-morbidity among 15 lifetime DSM-IV disorders. Discrete-time survival analysis was used to predict first onset of each disorder from information about prior history of the other 14 disorders.

RESULTS

Factor analysis found four factors representing fear, distress, behavior and substance disorders. Associations of temporally primary disorders with the subsequent onset of other disorders, dated using retrospective age-of-onset (AOO) reports, were almost entirely positive. Within-class associations (e.g. distress disorders predicting subsequent onset of other distress disorders) were more consistently significant (63.2%) than between-class associations (33.0%). Strength of associations decreased as co-morbidity among disorders increased. The percentage of lifetime disorders explained (in a predictive rather than a causal sense) by temporally prior disorders was in the range 3.7-6.9% for earliest-onset disorders [specific phobia and attention deficit hyperactivity disorder (ADHD)] and much higher (23.1-64.3%) for later-onset disorders. Fear disorders were the strongest predictors of most other subsequent disorders.

CONCLUSIONS

Adolescent mental disorders are highly co-morbid. The strong associations of temporally primary fear disorders with many other later-onset disorders suggest that fear disorders might be promising targets for early interventions.

Mechanisms of change: effects of repetitive exposure to feared stimuli on the brain's fear network

Repetitive exposure to feared stimuli is considered as the essential element in therapy with phobic patients. However, the mechanisms mediating symptom reduction and their underlying neurobiological processes are poorly understood. Therefore, we presented the same fear-relevant and neutral stimuli repeatedly to individuals with high and low fear of animals during fMRI scanning. High-, but not low-fearful individuals showed an initial fear-stimulus-related potentiation of amygdala and insula activity. Potentiation of the amygdala in the high-fearful group habituated quickly, but insula activity was still potentiated during later repetition trials. Both groups showed an initial potentiation of the dorsomedial prefrontal cortex (dmPFC) that continuously decreased in low-, but not in high-fearful participants. Thus, within-session habituation may occur on an automatic processing level (amygdala), but does not cause lasting neural changes on a higher order cortical level (dmPFC).

Glucocorticoid receptors and extinction retention deficits in the single prolonged stress model

Single prolonged stress (SPS) is a rodent model of post traumatic stress disorder that is comprised of serial application of restraint (r), forced swim (fs), and ether (eth) followed by a 7-day quiescent period. SPS induces extinction retention deficits and it is believed that these deficits are caused by the combined stressful effect of serial exposure to r, fs, and eth. However, this hypothesis remains untested. Neurobiological mechanisms by which SPS induces extinction retention deficits are unknown, but SPS enhances glucocorticoid receptor (GR) expression in the hippocampus, which is critical for contextual modulation of extinction retrieval. Upregulation of GRs in extinction circuits may be a mechanism by which SPS induces extinction retention deficits, but this hypothesis has not been examined. In this study, we systematically altered the stressors that constitute SPS (i.e. r, fs, eth), generating a number of partial SPS (p-SPS) groups, and observed the effects SPS and p-SPSs had on extinction retention and GR levels in the hippocampus and prefrontal cortex (PFC). PFC GRs were assayed, because regions of the PFC are critical for maintaining extinction. We predicted that only exposure to full SPS would result in extinction retention deficits and enhance hippocampal and PFC GR levels. Only exposure to full SPS induced extinction retention deficits. Hippocampal and PFC GR expression was enhanced by SPS and most p-SPSs, however hippocampal GR expression was significantly larger following the full SPS exposure than all other conditions. Our findings suggest that the combined stressful effect of serial exposure to r, fs, and eth results in extinction retention deficits. The results also suggest that simple enhancements in GR expression in the hippocampus and PFC are insufficient to result in extinction retention deficits, but raise the possibility that a threshold-enhancement in hippocampal GR expression contributes to SPS-induced extinction retention deficits.

Disorder-specific mental health service use for mood and anxiety disorders: associations with age, sex, and psychiatric comorbidity

BACKGROUND

The objectives of this study are to examine the prevalence of disorder-specific mental health service use for mood and anxiety disorders, and relationships between helpseeking and age, sex, and psychiatric comorbidity.

METHODS

The authors used Wave 2 data from the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC), which included 34,653 adults. Cross-tabulations provided helpseeking prevalence rates for five anxiety disorders and three mood disorders by age and sex, as well as for individuals with and without comorbid anxiety and mood disorders. Logistic regression analyses explored the likelihood of helpseeking among younger and middle-aged adults in comparison to older adults.

RESULTS

The prevalence of helpseeking was highest for panic disorder (45.3%) and dysthymia (44.5%) and lowest for specific phobias (7.8%). For each condition except panic disorder service use was most likely among middle-aged adults and especially unlikely among older individuals. Sex differences in treatment seeking favoring women showed only modest variability with age. Finally, the prevalence of helpseeking was generally lower among individuals without comorbid anxiety or mood disorders, and the hill-shaped influence of age on service use was attenuated in this pure group.

CONCLUSIONS

The results of this study highlight the highest prevalence of disorder-specific service use among middle-aged adults and women, and among individuals with panic disorder and dysthymia. For purposes of identifying groups who are in need of targeted efforts to increase service use, helpseeking was especially unlikely among people suffering from specific phobia, as well as among men and older adults.

Single prolonged stress disrupts retention of extinguished fear in rats

Clinical research has linked post-traumatic stress disorder (PTSD) with deficits in fear extinction. However, it is not clear whether these deficits result from stress-related changes in the acquisition or retention of extinction or in the regulation of extinction memories by context, for example. In this study, we used the single prolonged stress (SPS) animal model of PTSD and fear conditioning procedures to examine the effects of prior traumatic stress on the acquisition, retention, and context-specificity of extinction. SPS administered one week prior to fear conditioning had no effect on the acquisition of fear conditioning or extinction but disrupted the retention of extinction memories for both contextual and cued fear. This SPS effect required a post-stress incubation period to manifest. The results demonstrate that SPS disrupts extinction retention, leading to enhanced fear renewal; further research is needed to identify the neurobiological processes through which SPS induces these effects.

Arousal modulation of memory and amygdala-parahippocampal connectivity: a PET-psychophysiology study in specific phobia

Phobic fear is accompanied by intense bodily responses modulated by the amygdala. An amygdala moderated psychophysiological measure related to arousal is electrodermal activity. We evaluated the contributions of electrodermal activity to amygdala-parahippocampal regional cerebral blood flow (rCBF) during phobic memory encoding in subjects with spider or snake phobia. Recognition memory was increased for phobia-related slides and covaried with rCBF in the amygdala and the parahippocampal gyrus. The covariation between parahippocampal rCBF and recognition was related to electrodermal activity suggesting that parahippocampal memory processes were associated with sympathetic activity. Electrodermal activity further mediated the amygdala effect on parahippocampal activity. Memory encoding during phobic fear therefore seems contingent on amygdala's influence on arousal and parahippocampal activity.

Glucocorticoids enhance extinction-based psychotherapy

Behavioral exposure therapy of anxiety disorders is believed to rely on fear extinction. Because preclinical studies have shown that glucocorticoids can promote extinction processes, we aimed at investigating whether the administration of these hormones might be useful in enhancing exposure therapy. In a randomized, double-blind, placebo-controlled study, 40 patients with specific phobia for heights were treated with three sessions of exposure therapy using virtual reality exposure to heights. Cortisol (20 mg) or placebo was administered orally 1 h before each of the treatment sessions. Subjects returned for a posttreatment assessment 3-5 d after the last treatment session and for a follow-up assessment after 1 mo. Adding cortisol to exposure therapy resulted in a significantly greater reduction in fear of heights as measured with the acrophobia questionnaire (AQ) both at posttreatment and at follow-up, compared with placebo. Furthermore, subjects receiving cortisol showed a significantly greater reduction in acute anxiety during virtual exposure to a phobic situation at posttreatment and a significantly smaller exposure-induced increase in skin conductance level at follow-up. The present findings indicate that the administration of cortisol can enhance extinction-based psychotherapy.