Biology subjects

Hurlemann, R.

Publications and source records attributed to Hurlemann, R..

5 recordsLinked to original sources

bioRxiv2018

Impaired cognitive performance under psycho-social stress in cannabis dependence is mediated by attenuated precuneus activity

BackgroundDeficient regulation of stress plays an important role in the escalation of substance use, addiction and relapse. Accumulating evidence suggests dysregulations in cognitive and reward-related processes and the underlying neural circuitry in cannabis dependence. However, despite the important regulatory role of the endocannabinoid system in the stress response, associations between chronic cannabis use and altered stress processing on the neural level have not been systematically examined. MethodsAgainst this background, the present functional magnetic resonance imaging (fMRI)study examined psycho-social stress processing in cannabis-dependent males (n = 28) and matched controls (n = 23) using an established stress-induction paradigm (Montreal Imaging Stress Task) that combines computerized (adaptive) mental arithmetic challenges with social evaluative threat. ResultsDuring psycho-social stress exposure, but not the no-stress condition, cannabis users demonstrated impaired performance relative to controls. In contrast, levels of experienced stress and cardiovascular stress responsivity did not differ from controls. Functional MRI data revealed that stress-induced performance deteriorations in cannabis users were accompanied by decreased precuneus activity and increased connectivity of this region with the dorsal medial prefrontal cortex. LimitationsOnly male cannabis-dependent users were examined, the generalizability in female users remains to be determined. ConclusionTogether, the present findings provide first evidence for exaggerated stress-induced cognitive performance deteriorations in cannabis users. The neural data suggest that deficient stress-related dynamics of the precuneus may mediate the deterioration of performance on the behavioral level.

neuroscience↗

bioRxiv2018

Comparative efficacy and acceptability of non-surgical brain stimulation for the acute treatment of adult major depressive episodes: A systematic review and network meta-analysis of 113 randomised clinical trials

Background: Non-surgical brain stimulation techniques have been applied as tertiary treatments in major depression. However, the relative efficacy and acceptability of individual protocols is uncertain. Our aim was to estimate the comparative clinical efficacy and acceptability of non-surgical brain stimulation for the acute treatment of major depressive episodes in adults.\n\nMethods: Embase, PubMed/MEDLINE and PsycINFO were searched up until May 8, 2018, supplemented by manual searches of bibliographies of recent reviews and included trials. We included clinical trials with random allocation to electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), accelerated TMS (aTMS), priming TMS (pTMS), deep TMS (dTMS), theta burst stimulation (TBS), synchronised TMS (sTMS), magnetic seizure therapy (MST) or transcranial direct current stimulation (tDCS) protocols or sham. Data were extracted from published reports and outcomes were synthesised using pairwise and network random-effects meta-analysis. Primary outcomes were response (efficacy) and all-cause discontinuation (acceptability). We computed odds ratios (OR) with 95% confidence intervals (CI). Remission and continuous post-treatment depression severity scores were also examined.\n\nResults: 113 trials (262 treatment arms) randomising 6,750 patients (mean age = 47.9 years; 59% female) with major depressive disorder or bipolar depression met our inclusion criteria. In terms of efficacy, 10 out of 18 treatment protocols were associated with higher response relative to sham in network meta-analysis: bitemporal ECT (OR=8.91, 95%CI 2.57-30.91), high-dose right-unilateral ECT (OR=7.27, 1.90-27.78), pTMS (OR=6.02, 2.21-16.38), MST (OR=5.55, 1.06-28.99), bilateral rTMS (OR=4.92, 2.93-8.25), bilateral TBS (OR=4.44, 1.47-13.41), low-frequency right rTMS (OR=3.65, 2.13-6.24), intermittent TBS (OR=3.20, 1.45-7.08), high-frequency left rTMS (OR=3.17, 2.29-4.37) and tDCS (OR=2.65, 1.55-4.55). Comparing active treatments, bitemporal ECT and high-dose right-unilateral ECT were associated with increased response. All treatment protocols were at least as acceptable as sham treatment.\n\nConclusion: We found that non-surgical brain stimulation techniques constitute viable alternative or add-on treatments for adult patients with major depressive episodes. Our findings also highlight the need to consider other patient and treatment-related factors in addition to antidepressant efficacy and acceptability when making clinical decisions; and emphasize important research priorities in the field of brain stimulation.\n\nO_LSTTreatment abbreviationsC_LSTECT = Electroconvulsive Therapy O_LIBF ECT = bifrontal ECT (1)\nC_LIO_LIBT ECT = bitemporal ECT (2)\nC_LIO_LIRUL ECT= right unilateral ECT O_LIH-RUL = high-dose RUL ECT (3)\nC_LIO_LILM-RUL = low to moderate-dose RUL ECT (4)\nC_LI\nC_LI\nrTMS = repetitive Transcranial Magnetic Stimulation O_LIHF-L rTMS = high-frequency rTMS of the left DLPFC (5)\nC_LIO_LIHF-R rTMS = high-frequency rTMS of the right DLPFC (6)\nC_LIO_LILF-R rTMS = low-frequency rTMS of the right DLPFC (7)\nC_LIO_LILF-L rTMS = low-frequency rTMS of the left DLPFC (8)\nC_LIO_LIBL rTMS = bilateral rTMS of the DLPFC (9)\nC_LI\ndTMS = deep Transcranial Magnetic Stimulation (10)\npTMS = priming Transcranial Magnetic Stimulation (11)\naTMS = accelerated Transcranial Magnetic Stimulation (12)\nsTMS = synchronised Transcranial Magnetic Stimulation (13)\nTBS = Theta Burst Stimulation O_LIiTBS = intermittent TBS of the left DLPFC (14)\nC_LIO_LIcTBS = continuous TBS of the right DLPFC (15)\nC_LIO_LIblTBS = bilateral TBS of the DLPFC (16)\nC_LI\nMST = Magnetic Seizure Therapy (17)\ntDCS = transcranial Direct Current Stimulation (18)\n\n\nKey points\n\nQuestion: What is the clinical efficacy and acceptability of non-surgical brain stimulation protocols for the acute treatment of major depressive episodes in adults?\n\nFindings: In this network meta-analysis, 10 out of 18 treatment protocols were associated with higher response rates relative to sham, most notably bitemporal and high-dose right unilateral electroconvulsive therapy. All treatment protocols were at least as acceptable as sham treatment.\n\nMeaning: Non-surgical brain stimulation techniques constitute viable alternative or add-on treatment strategies for adult patients with major depressive episodes.

neuroscience↗

bioRxiv2018

Oxytocin enhancement of emotional empathy: generalization across cultures and effects on amygdala activity

Accumulating evidence suggests that the neuropeptide oxytocin can enhance empathy although it is unclear which specific behavioral and neural aspects are influenced, and whether the effects are modulated by culture, sex and trait autism. Based on previous findings in Caucasian men, we hypothesized that a single intranasal dose of oxytocin would specifically enhance emotional empathy via modulatory effects on the amygdala in an Asian (Chinese) population and explored the modulatory role of sex and trait autism on the effects. We first conducted a double-blind, randomized between-subject design experiment using a modified version of the multifaceted empathy task (MET) to determine whether oxytocins facilitation of emotional empathy can be replicated in Chinese men (n = 60). To further explore neural mechanisms behind and potential sex differences, functional MRI and skin conductance measures were acquired in an independent experiment incorporating men and women (n = 72). Oxytocin enhanced emotional empathy across experiments and sex, an effect that was accompanied by reduced amygdala activity and increased skin conductance responses. On the network level oxytocin enhanced functional coupling of the right amygdala with the insula and posterior cingulate cortex for positive valence stimuli but attenuated coupling for negative valence stimuli. The effect of oxytocin on amygdala functional connectivity with the insula was modulated by trait autism. Overall, our findings provide further support for the role of oxytocin in facilitating emotional empathy and demonstrate that effects are independent of culture and sex and involve modulatory effects on the amygdala and its interactions with other key empathy regions.

neuroscience↗

bioRxiv2018

Shifted balance of dorsal versus ventral striatal communication with frontal reward and regulatory regions in cannabis dependence

The transition from voluntary to addictive behavior is characterized by a loss of regulatory control in favor of reward driven behavior. Animal models indicate that this process is neurally underpinned by a shift in ventral to dorsal striatal control of behavior, however this shift has not been directly examined in humans. Against this background the present resting state fMRI study employed a two-step approach to (1) precisely map striatal alterations using a novel, data-driven network classification strategy combining Intrinsic Connectivity Contrast (ICC) with Multivoxel Pattern Analysis (MVPA) and, (2) to determine whether a ventral to dorsal striatal shift in connectivity with reward and and regulatory control regions can be observed in abstinent (28 days) male cannabis-dependent individuals (n = 24) relative to matched controls (n = 28). Network classification revealed that the groups can be reliably discriminated by global connectivity profiles of two striatal regions that mapped onto the ventral (nucleus accumbens) and dorsal striatum (caudate). Subsequent functional connectivity analysis demonstrated a relative shift between ventral and dorsal striatal communication with fronto-limbic regions that have been consistently involved in reward processing (rostral ACC) and executive / regulatory functions (dorsomedial PFC). Specifically, in the cannabis dependent subjects connectivity between the ventral striatum with the rostral ACC increased, whereas both striatal regions were uncoupled from the regulatory dorsomedial PFC. Together these findings suggest a shift in the balance between dorsal and ventral striatal control in cannabis dependence. Similar changes have been observed in animal models and may promote the loss of control central to addictive behavior.

neuroscience↗

bioRxiv2018

Altered Reward Processing in Abstinent Dependent Cannabis Users: Social Context Matters

Public perception of cannabis as relatively harmless, alongside claimed medical benefits, have led to moves towards its legalization. Yet, long-term consequences of cannabis dependence, and whether they differ qualitatively from other drugs, are still poorly understood. A key feature of addictive drugs is that chronic use leads to adaptations in reward processing, blunting responsivity to the substance itself and other rewarding stimuli. Against this background, the present study investigated whether cannabis dependence is associated with reductions in hedonic representations by measuring behavioral and neural responses to social reward in 23 abstinent cannabis-dependent men and 24 matched non-using controls. In an interpersonal pleasant touch fMRI paradigm, participants were led to believe they were in physical closeness of or touched (CLOSE, TOUCH) by either a male or female experimenter (MALE, FEMALE), allowing the assessment of touch- and social context-dependent (i.e. female compared to male social interaction) reward dynamics.\n\nUpon female compared to male touch, dependent cannabis users displayed a significantly attenuated increase of reward experience compared to healthy controls. Controls responded to female as compared to male interaction with increased striatal activation whereas cannabis users displayed the opposite activation pattern, with stronger alterations being associated with a higher lifetime exposure to cannabis. Neural processing of pleasant touch in dependent cannabis users remained intact.\n\nThese findings demonstrate that cannabis dependence in men is linked to similar lasting neuroadaptations in striatal responsivity to hedonic stimuli as observed for other drugs of abuse. However, reward processing deficits seem to depend on the social context.

neuroscience↗