A Note on the Structural Change Test in Highly Parameterized Psychometric Models.

Equal parameter estimates across subgroups is a substantial requirement of statistical tests. Ignoring subgroup differences poses a threat to study replicability, model specification, and theory development. Structural change tests are a powerful statistical technique to assess parameter invariance. A core element of those tests is the empirical fluctuation process. In the case of parameter invariance, the fluctuation process asymptotically follows a Brownian bridge. This asymptotic assumption further provides the basis for inference. However, the empirical fluctuation process does not follow a Brownian bridge in small samples, and this situation is amplified in large psychometric models. Therefore, common methods of obtaining the sampling distribution are invalid and the structural change test becomes conservative. We discuss an alternative solution to obtaining the sampling distribution-permutation approaches. Permutation approaches estimate the sampling distribution through resampling of the dataset, avoiding distributional assumptions. Hereby, the tests power are improved. We conclude that the permutation alternative is superior to standard asymptotic approximations of the sampling distribution.

Modeling alcohol use disorder as a set of interconnected symptoms - Assessing differences between clinical and population samples and across external factors.

Alcohol use disorder is argued to be a highly complex disorder influenced by a multitude of factors on different levels. Common research approaches fail to capture this breadth of interconnecting symptoms. To address this gap in theoretical assumptions and methodological approaches, we used a network analysis to assess the interplay of alcohol use disorder symptoms. We applied the exploratory analysis to two US-datasets, a population sample with 23,591 individuals and a clinical sample with 483 individuals seeking treatment for alcohol use disorder. Using a Bayesian framework, we first investigated differences between the clinical and population sample looking at the symptom interactions and underlying structure space. In the population sample the time spent drinking alcohol was most strongly connected, whereas in the clinical sample loss of control showed most connections. Furthermore, the clinical sample demonstrated less connections, however, estimates were too unstable to conclude the sparsity of the network. Second, for the population sample we assessed whether the network was measurement invariant across external factors like age, gender, ethnicity and income. The network differed across all factors, especially for age subgroups, indicating that subgroup specific networks should be considered when deriving implications for theory building or intervention planning. Our findings corroborate known theories of alcohol use disorder stating loss of control as a central symptom in alcohol dependent individuals.

[Neuromodulation as an intervention for addiction: overview and future prospects]. / Neuromodulatie als interventie voor verslaving: stand van zaken en toekomstperspectief.

BACKGROUND: In recent years several neuromodulation techniques have been introduced as interventions for addiction. AIM: To review and discuss studies that have investigated the effects of treating addiction by means of electroencephalography (EEG) neurofeedback, real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback, transcranial magnetic stimulation/transcranial direct current stimulation (TMS/tDCS) and deep brain stimulation (DBS). METHOD: We reviewed the literature, focusing on Dutch studies in particular. RESULTS: Studies using EEG neurofeedback were shown to have positive effects on drug use, treatment compliance, and cue reactivity in patients with cocaine and alcohol dependence. A pilot study investigating the effects of rt-fMRI neurofeedback on nicotine dependent patients showed that modulation of the anterior cingulate cortex can decrease smokers' craving for nicotine. In several studies decreased craving was found in alcohol dependent patients after TMS or tDCS stimulation of the anterior cingulate cortex or the dorsolateral prefrontal cortex. The first DBS pilot studies suggest that the nucleus accumbens is a promising target region for the treatment of alcohol and heroin dependence. CONCLUSION: Neuromodulation provides us with a unique opportunity to directly apply neuroscientific knowledge to the treatment of addiction. However, more research is needed to ensure the efficacy, safety and feasibility of the various neuromodulation techniques that are now available.

Deep brain stimulation in addiction: a review of potential brain targets.

Deep brain stimulation (DBS) is an adjustable, reversible, non-destructive neurosurgical intervention using implanted electrodes to deliver electrical pulses to areas in the brain. DBS is currently investigated in psychiatry for the treatment of refractory obsessive-compulsive disorder, Tourette syndrome and depressive disorder. Although recent research in both animals and humans has indicated that DBS may be an effective intervention for patients with treatment-refractory addiction, it is not yet entirely clear which brain areas should be targeted. The objective of this review is to provide a systematic overview of the published literature on DBS and addiction and outline the most promising target areas using efficacy and adverse event data from both preclinical and clinical studies. We found 7 animal studies targeting six different brain areas: nucleus accumbens (NAc), subthalamic nucleus (STN), dorsal striatum, lateral habenula, medial prefrontal cortex (mPFC) and hypothalamus, and 11 human studies targeting two different target areas: NAc and STN. Our analysis of the literature suggests that the NAc is currently the most promising DBS target area for patients with treatment-refractory addiction. The mPFC is another promising target, but needs further exploration to establish its suitability for clinical purposes. We conclude the review with a discussion on translational issues in DBS research, medical ethical considerations and recommendations for clinical trials with DBS in patients with addiction.