The effect of low-frequency rTMS on auditory hallucinations, EEG source localization and functional connectivity in schizophrenia

BACKGROUND

Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) diminishes auditory hallucinations (AHs). The aims of our study were a) to assess the efficacy of LF-rTMS in a randomized, sham-controlled double-blind alignment, b) to identify the electrophysiological changes accompanying the LF-rTMS, and c) to identify the influence of LF-rTMS on brain functional connectivity (FC).

METHODS

Nineteen schizophrenia patients with antipsychotic-resistant AHs were randomized to either active (n = 10) or sham (n = 9) LF-rTMS administered over the left temporo-parietal region for ten days. The clinical effect was assessed by the Auditory Hallucination Rating Scale (AHRS). The localization of the differences in electrical activity was identified by standardized low resolution brain electromagnetic tomography (sLORETA) and FC was measured by lagged phase synchronization.

RESULTS

AHRS scores were significantly improved for patients receiving active rTMS compared to the sham (median reduction: 40 % vs 12 %; p = 0.01). sLORETA revealed a decrease of alpha-2, beta-1,-2 bands in the left hemisphere in the active group. Active rTMS led to a decrease of the lagged phase connectivity in beta bands originating in areas close to the site of stimulation, and to a prevailing increase of alpha-2 FC. No significant differences in current density or FC were observed in the sham group.

LIMITATIONS

Limitations to our study included the small group sizes, and the disability of LORETA to assess subcortical neuronal activity.

CONCLUSIONS

LF-rTMS attenuated AHs and induced a decrease of higher frequency bands on the left hemisphere. The FC changes support the assumption that LF-rTMS is linked to the modulation of cortico-cortical coupling.

Functional Connectivity Changes in Obsessive-Compulsive Disorder Correspond to Interference Control and Obsessions Severity

Introduction: Deficits in neurocognitive mechanisms such as inhibition control and cognitive flexibility have been suggested to mediate the symptoms in obsessive-compulsive disorder (OCD). These mechanisms are proposedly controlled by the "affective" and "executive" orbitofronto-striato-thalamo-cortical (CSTC) circuits with well-documented morphological and functional alterations in OCD that are associated with OCD symptoms. The precuneus region has been suggested in OCD as another key structure associated with the mechanism of "thought-action fusion." Our study aimed to elucidate the association of the altered functional coupling of the CSTC nodes (and precuneus), the OCD symptoms, and interference control/cognitive flexibility. Methods: In a group of 36 (17 medicated and 19 drug-free) OCD patients and matched healthy volunteers, we tested functional connectivity (FC) within the constituents of the dorsolateral prefrontal cortex "executive" CSTC, the orbitofrontal cortex/anterior cingulate "affective" CSTC, and precuneus. The functional connections showing the strongest effects were subsequently entered as explanatory variables to multiple regression analyses to identify possible associations between observed alterations of functional coupling and cognitive (Stroop test) and clinical measures (obsessions, compulsions, and anxiety level). Results: We observed increased FC (FWE p < 0.05 corr.) between CSTC seeds and regions of the parieto-occipital cortex, and between the precuneus and the angular gyrus and dorsolateral prefrontal cortex. Decreased FC was observed within the CSTC loop (caudate nucleus and thalamus) and between the anterior cingulate cortex and the limbic lobe. Linear regression identified a relationship between the altered functional coupling of thalamus with the right somatomotor parietal cortex and the Stroop color-word score. Similar association of thalamus FC has been identified also for obsessions severity. No association was observed for compulsions and anxiety. Conclusions: Our findings demonstrate altered FC in OCD patients with a prevailing increase in FC originating in CSTC regions toward other cortical areas, and a decrease in FC within the constituents of CSTC loops. Moreover, our results support the role of precuneus in OCD. The association of the cognitive and clinical symptoms with the FC between the thalamus and somatomotor cortex indicates that cognitive flexibility and inhibitory control are strongly linked and both mechanisms might contribute to the symptomatology of OCD.

Structural and construct validity of the Czech version of the Pittsburgh Sleep Quality Index in chronic insomnia

OBJECTIVES

The Pittsburgh Sleep Quality Index (PSQI) is one of the widely used and recommended measures of assessing sleep quality in chronic insomnia; however certain psychometric properties of the questionnaire are still unknown in this group of patients. The present study aimed to examine the internal consistency, and structural and convergent validity of the Czech version of the PSQI in chronic insomnia patients. The usefulness of the standard and alternative scoring systems was also investigated in relation to symptoms of sleepiness, insomnia, depression, and anxiety.

METHODS

In our study, 105 participants filled out a series of questionnaires including PSQI, Insomnia Severity Index (ISI), Epworth Sleepiness Scale (ESS), and Beck Depression and Anxiety Inventories (BDI, BAI).

RESULTS

The internal consistency of the questionnaire using Cronbach's alpha was 0.608. A series of confirmatory factor analyses revealed adequate fit for three structures. A three-factor model descriptively stood out among the rest but subsequent correlational analyses did not provide sufficient support for accepting an alternative scoring model.

CONCLUSIONS

The results highlight the issue of structural variance of the PSQI and in chronic insomnia point to the important role of the PSQI components of daytime dysfunction and sleep disturbances in showing comorbid symptoms with daytime sleepiness and psychopathology.

Validity of Quinpirole Sensitization Rat Model of OCD: Linking Evidence from Animal and Clinical Studies

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder with 1–3% prevalence. OCD is characterized by recurrent thoughts (obsessions) and repetitive behaviors (compulsions). The pathophysiology of OCD remains unclear, stressing the importance of pre-clinical studies. The aim of this article is to critically review a proposed animal model of OCD that is characterized by the induction of compulsive checking and behavioral sensitization to the D2/D3 dopamine agonist quinpirole. Changes in this model have been reported at the level of brain structures, neurotransmitter systems and other neurophysiological aspects. In this review, we consider these alterations in relation to the clinical manifestations in OCD, with the aim to discuss and evaluate axes of validity of this model. Our analysis shows that some axes of validity of quinpirole sensitization model (QSM) are strongly supported by clinical findings, such as behavioral phenomenology or roles of brain structures. Evidence on predictive validity is contradictory and ambiguous. It is concluded that this model is useful in the context of searching for the underlying pathophysiological basis of the disorder because of the relatively strong biological similarities with OCD.

Obsessive compulsive disorder and dissociation - comparison with healthy controls

The aim of our study is to examine if the dissociation can influence the intensity of psychopathology in patients suffering from obsessive compulsive disorder and to compare the levels of dissociation in the groups of the patients and healthy subjects. Method. Fifty five patients suffering from obsessive compulsive disorder and 123 healthy controls were included into the study. The patients were psychiatrically assessed. The diagnosis was made using ICD-10 research criteria confirmed with structured interview MINI. The subjective intensity of anxiety and depressive symptoms was evaluated using Beck Anxiety Inventory and Beck Depression Inventory. The intensity of obsessions and compulsions was evaluated using Yale Brown Obsessive Compulsive Scale. All participants were assessed with the Dissociative Experiences Scale (DES). Results. Level of the psychological dissociation assessed with the DES was correlated with the severity of subjective anxiety (p<0.0001), depression (p<0.0001), and with the severity of obsessive-compulsive symptoms (p<0.005). Patients have significantly lower mean score on the DES than healthy controls (p<0.0001). Conclusion. Our results suggest that the level of psychological dissociation in OCD patients is lower than in healthy controls, and is associated with the severity of anxiety, depression and obsessive compulsive symptoms.

Subanesthetic dose of ketamine decreases prefrontal theta cordance in healthy volunteers: implications for antidepressant effect

BACKGROUND

Theta cordance is a novel quantitative electroencephalography (QEEG) measure that correlates with cerebral perfusion. A series of clinical studies has demonstrated that the prefrontal theta cordance value decreases after 1 week of treatment in responders to antidepressants and that this effect precedes clinical improvement. Ketamine, a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors, has a unique rapid antidepressant effect but its influence on theta cordance is unknown.

METHOD

In a double-blind, cross-over, placebo-controlled experiment we studied the acute effect of ketamine (0.54 mg/kg within 30 min) on theta cordance in a group of 20 healthy volunteers.

RESULTS

Ketamine infusion induced a decrease in prefrontal theta cordance and an increase in the central region theta cordance after 10 and 30 min. The change in prefrontal theta cordance correlated with ketamine and norketamine blood levels after 10 min of ketamine infusion.

CONCLUSIONS

Our data indicate that ketamine infusion immediately induces changes similar to those that monoamineric-based antidepressants induce gradually. The reduction in theta cordance could be a marker and a predictor of the fast-acting antidepressant effect of ketamine, a hypothesis that could be tested in depressive patients treated with ketamine.

Predicting the therapeutic response to cognitive behavioural therapy in patients with pharmacoresistant obsessive-compulsive disorder

OBJECTIVE

The aim of our study was to establish the efficacy of CBT on the sample of non-selected medication-resistant patients with OCD and to search for predictors of therapeutic response in such a group.

METHODS

The treatment was carried out under usual conditions at the department for anxiety disorders. Systematic CBT steps were tailored to the needs of each patient. Pharmacology treatment remained grossly unchanged during the trial period. We used the following outcome measures in the study: Yale-Brown Obsessive Compulsive Scale, subjective version (S-Y-BOCS), the Clinical Global Impression - Severity of Illness scale (CGI-S), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Somatoform Dissociation Questionnaire (SDQ-20) and Dissociative Experience Scale (DES). The primary outcome measure was a decrease by 35% in Y-BOCS rating. Remission was defined as a 12 point score or lower in Y-BOCS and 1 or 2 points in CGI-S.

RESULTS

47 patients completed the study (19 male and 28 female). One female patient refused to participate. All patients completed at least 5 weeks of intensive CBT programme and showed significant improvement on Y-BOCS, CGI-S, and BDI scales. At the end of the treatment 40.4% of the patients achieved clinical remission according to the CGI-S scale. The main characteristics present at the beginning of the trial increasing probability of achieving improvement or remission during the treatment were a Y-BOCS score lower than 22, good insight, higher resistance to symptoms, low level of dissociation, and aggressive obsessions.

CONCLUSION

As negative predictors we identified higher scores in Y-BOCS, poorer insight, low resistance to symptoms, high level of dissociation, obsessions focused on control/symmetry and obsessive slowness/ambivalence as associated with poor improvement.