Max C. Keuken

Curbing problem drinking with personalized-feedback interventions. A meta-analysis

CONTEXT The effectiveness of personalized-feedback interventions to reduce problem drinking has been evaluated in several RCTs and systematic reviews. A meta-analysis was performed to examine the overall effectiveness of brief, single-session personalized-feedback interventions without therapeutic guidance. EVIDENCE ACQUISITION The selection and analyses of studies were conducted in 2008. Fourteen RCTs of single-session personalized-feedback interventions without therapeutic guidance were identified, and their combined effectiveness on the reduction of problematic alcohol consumption was evaluated in a meta-analysis. Alcohol consumption was the primary outcome measure. EVIDENCE SYNTHESIS The pooled standardized-effect size (14 studies, 15 comparisons) for reduced alcohol consumption at post-intervention was d=0.22 (95% CI=0.16, 0.29; the number needed to treat=8.06; areas under the curve=0.562). No heterogeneity existed among the studies (Q=10.962; p=0.69; I(2)=0). CONCLUSIONS The use of single-session personalized-feedback interventions without therapeutic guidance appears to be a viable and probably cost-effective option for reducing problem drinking in student and general populations. The Internet offers ample opportunities to deliver personalized-feedback interventions on a broad scale, and problem drinkers are known to be amenable to Internet-based interventions. More research is needed on the long-term effectiveness of personalized-feedback interventions for problem drinking, on its potential as a first step in a stepped-care approach, and on its effectiveness with other groups (such as youth obliged to use judicial service programs because of violations of minimum-age drinking laws) and in other settings (such as primary care).

Cortico-subthalamic white matter tract strength predicts interindividual efficacy in stopping a motor response

The subthalamic nucleus (STN) is a small but vitally important structure in the basal ganglia. Because of its small volume, and its localization in the basal ganglia, the STN can best be visualized using ultra-high resolution 7 Tesla (T) magnetic resonance imaging (MRI). In the present study, first we individually segmented 7 T MRI STN masks to generate atlas probability maps. Secondly, the individually segmented STN masks and the probability maps were used to derive cortico-subthalamic white matter tract strength. Tract strength measures were then taken to test two functional STN hypotheses which account for the efficiency in stopping a motor response: the right inferior fronto-subthalamic (rIFC-STN) hypothesis and the posterior medial frontal cortex-subthalamic (pMFC-STN) hypothesis. Results of two independent experiments show that increased white matter tract strength between the pMFC and STN results in better stopping behaviour.

Quantifying inter-individual anatomical variability in the subcortex using 7 T structural MRI.

Functional magnetic resonance imaging (MRI) data are usually registered into standard anatomical space. However, standard atlases, such as LPBA40, the Harvard-Oxford atlas, FreeSurfer, and the Jülich cytoarchitectonic maps all lack important detailed information about small subcortical structures like the substantia nigra and subthalamic nucleus. Here we introduce a new subcortical probabilistic atlas based on ultra-high resolution in-vivo anatomical imaging from 7 T MRI. The atlas includes six important but elusive subcortical nuclei: the striatum, the globus pallidus internal and external segment (GPi/e), the subthalamic nucleus, the substantia nigra, and the red nucleus. With a sample of 30 young subjects and carefully cross-validated delineation protocols, our atlas is able to capture the anatomical variability within healthy populations for each of the included structures at an unprecedented level of detail. All the generated probabilistic atlases are registered to MNI standard space and are publicly available.

Ultra-high 7T MRI of structural age-related changes of the subthalamic nucleus

The subthalamic nucleus (STh) is a small subcortical structure which is involved in regulating motor as well as cognitive functions. Due to its small size and close proximity to other small subcortical structures, it has been a challenge to localize and visualize it using magnetic resonance imaging (MRI). Currently there are several standard atlases available that are used to localize the STh in functional MRI studies and clinical procedures such as deep brain stimulation (DBS). DBS is an increasingly common neurosurgical procedure that has been successfully used to alleviate motor symptoms present in Parkinsons disease. However, current atlases are based on low sample sizes and restricted age ranges (Schaltenbrand and Wahren, 1977), and hence the use of these atlases effectively ignores the substantial structural brain changes that are associated with aging. In the present study, ultra-high field 7 tesla (T) magnetic resonance imaging (MRI) in humans was used to visualize and segment the STh in young, middle-aged, and elderly participants. The resulting probabilistic atlas maps for all age groups show that the STh shifts in the lateral direction with increasing age. In sum, the results of the present study suggest that age has to be taken into account in atlases for the optimal localization of the STh in healthy and diseased brains.

The role of the left inferior frontal gyrus in social perception: an rTMS study.

Perceiving and interpreting social information richness is something that humans do automatically whenever they engage in social interactions. Numerous studies have identified neural substrates, including mirror neurons that may enable such social perception. In this study, we temporarily disrupted activity in the left inferior frontal gyrus (LIFG) using repetitive transcranial magnetic stimulation (rTMS). We investigated whether this cortical region, that is hypothesized to include mirror neurons, plays a central role in social perception. The LIFG was stimulated in the experimental condition (n=18), the vertex was targeted in the control condition (n=19). Disrupting LIFG, but not vertex, increased reaction times during an emotion recognition task, and eliminated the suppression of the 8-12Hz EEG μ rhythm, postulated as an index of mirroring activity. The results of this study provide further evidence for the role of the human mirror neuron system (MNS) in social perception, and indicate that the MNS can be measured with EEG.

Tms over m1 reveals expression and selective suppression of conflicting action impulses

Goal-directed action control comes into play when selecting between competing action alternatives. Response capture reflects the susceptibility of the motor system to incitement by task-irrelevant action impulses; the subsequent selective suppression of incorrect action impulses aims to counteract response capture and facilitate the desired response. The goal of this experiment was to clarify physiological mechanisms of response capture and suppression of action impulses during conflict at the level of the motor system. We administered single-pulse TMS at various intervals preceding speeded choice responses. The correct response side was designated by stimulus color, whereas stimulus location (which could match or conflict with response side) was to be ignored. TMS pulses triggered motor evoked potential and silent period, providing sensitive indices of cortico-spinal excitation and inhibition. Motor evoked potential data showed the typical progressive increase in cortico-spinal motor excitability leading up to the imminent (correct) response, which started earlier on nonconflict than on conflict trials. On conflict trials, the irrelevant stimulus location captured the incorrect response, as expressed by an early and transient rise in excitability. Silent period data showed that, already early during the response process, inhibition of the incorrect response was stronger for conflict than for nonconflict trials. Furthermore, inhibition decreased over time for nonconflict trials facilitating the imminent correct response while maintaining higher levels of inhibition on conflict trials. In conclusion, dynamic patterns of cortico-spinal excitability provide unique physiological evidence for the expression and selective suppression of action impulses captured by competing action alternatives.

Predicting Successful Treatment Outcome of Web-Based Self-help for Problem Drinkers: Secondary Analysis From a Randomized Controlled Trial

Background Web-based self-help interventions for problem drinking are coming of age. They have shown promising results in terms of cost-effectiveness, and they offer opportunities to reach out on a broad scale to problem drinkers. The question now is whether certain groups of problem drinkers benefit more from such Web-based interventions than others. Objective We sought to identify baseline, client-related predictors of the effectiveness of Drinking Less, a 24/7, free-access, interactive, Web-based self-help intervention without therapist guidance for problem drinkers who want to reduce their alcohol consumption. The intervention is based on cognitive-behavioral and self-control principles. Methods We conducted secondary analysis of data from a pragmatic randomized trial with follow-up at 6 and 12 months. Participants (N = 261) were adult problem drinkers in the Dutch general population with a weekly alcohol consumption above 210 g of ethanol for men or 140 g for women, or consumption of at least 60 g (men) or 40 g (women) one or more days a week over the past 3 months. Six baseline participant characteristics were designated as putative predictors of treatment response: (1) gender, (2) education, (3) Internet use competence (sociodemographics), (4) mean weekly alcohol consumption, (5) prior professional help for alcohol problems (level of problem drinking), and (6) participants’ expectancies of Web-based interventions for problem drinking. Intention-to-treat (ITT) analyses, using last-observation-carried-forward (LOCF) data, and regression imputation (RI) were performed to deal with loss to follow-up. Statistical tests for interaction terms were conducted and linear regression analysis was performed to investigate whether the participants’ characteristics as measured at baseline predicted positive treatment responses at 6- and 12-month follow-ups. Results At 6 months, prior help for alcohol problems predicted a small, marginally significant positive treatment outcome in the RI model only (beta = .18, P = .05, R2 = .11). At 12 months, females displayed modest predictive power in both imputation models (LOCF: beta = .22, P = .045, R2 = .02; regression: beta = .27, P = .01, R2 = .03). Those with higher levels of education exhibited modest predictive power in the LOCF model only (beta = .33, P = .01, R2 = .03). Conclusions Although female and more highly educated users appeared slightly more likely to derive benefit from the Drinking Less intervention, none of the baseline characteristics we studied persuasively predicted a favorable treatment outcome. The Web-based intervention therefore seems well suited for a heterogeneous group of problem drinkers and could hence be offered as a first-step treatment in a stepped-care approach directed at problem drinkers in the general population. Trial Registration International Standard Randomized Controlled Trial Number (ISRCTN): 47285230; http://www.controlled-trials.com/isrctn47285230 (Archived by WebCite at http://www.webcitation.org/5cSR2sMkp).

Multi-modal ultra-high resolution structural 7-Tesla MRI data repository

Structural brain data is key for the understanding of brain function and networks, i.e., connectomics. Here we present data sets available from the ‘atlasing of the basal ganglia (ATAG)’ project, which provides ultra-high resolution 7 Tesla (T) magnetic resonance imaging (MRI) scans from young, middle-aged, and elderly participants. The ATAG data set includes whole-brain and reduced field-of-view MP2RAGE and T2*-weighted scans of the subcortex and brainstem with ultra-high resolution at a sub-millimeter scale. The data can be used to develop new algorithms that help building high-resolution atlases both relevant for the basic and clinical neurosciences. Importantly, the present data repository may also be used to inform the exact positioning of electrodes used for deep-brain-stimulation in patients with Parkinson’s disease and neuropsychiatric diseases.

Are there three subdivisions in the primate subthalamic nucleus

The prevailing academic opinion holds that the subthalamic nucleus (STN) consists of three parts, each anatomically distinct and selectively associated with cognitive, emotional, or motor functioning. We independently tested this assumption by summarizing the results from 33 studies on STN subdivisions in human and nonhuman primates. The studies were conducted from 1925 to 2010 and feature three different techniques: electrical lesions, anterograde and retrograde tracers, and classical cytoarchitectonics. Our results reveal scant evidence in support of a tripartite STN. Instead, our results show that the variability across studies is surprisingly large, both in the number of subdivisions and in their anatomical localization. We conclude that the number of subdivisions in the STN remains uncertain, and that academic consensus in support of a tripartite STN is presently unwarranted.

A gradual increase of iron toward the medial‐inferior tip of the subthalamic nucleus

The subthalamic nucleus (STN) is an important node of the cortico‐basal ganglia network and the main target of deep brain stimulation (DBS) in Parkinsons disease. Histological studies have revealed an inhomogeneous iron distribution within the STN, which has been related to putative subdivisions within this nucleus. Here, we investigate the iron distribution in more detail using quantitative susceptibility mapping (QSM), a novel magnetic resonance imaging (MRI) contrast mechanism. QSM allows for detailed assessment of iron content in both in vivo and postmortem tissue. Twelve human participants and 7 postmortem brain samples containing the STN were scanned using ultra‐high field 7 Tesla (T) MRI. Iron concentrations were found to be higher in the medial‐inferior tip of the STN. Using quantitative methods we show that the increase of iron concentration towards the medial‐inferior tip is of a gradual rather than a discrete nature. Hum Brain Mapp 35:4440–4449, 2014.