Transcranial Direct Current Stimulation for Chronic Stroke: Is Neuroimaging the Answer to the Next Leap Forward?

During rehabilitation, a large proportion of stroke patients either plateau or begin to lose motor skills. By priming the motor system, transcranial direct current stimulation (tDCS) is a promising clinical adjunct that could augment the gains acquired during therapy sessions. However, the extent to which patients show improvements following tDCS is highly variable. This variability may be due to heterogeneity in regions of cortical infarct, descending motor tract injury, and/or connectivity changes, all factors that require neuroimaging for precise quantification and that affect the actual amount and location of current delivery. If the relationship between these factors and tDCS efficacy were clarified, recovery from stroke using tDCS might be become more predictable. This review provides a comprehensive summary and timeline of the development of tDCS for stroke from the viewpoint of neuroimaging. Both animal and human studies that have explored detailed aspects of anatomy, connectivity, and brain activation dynamics relevant to tDCS are discussed. Selected computational works are also included to demonstrate how sophisticated strategies for reducing variable effects of tDCS, including electric field modeling, are moving the field ever closer towards the goal of personalizing tDCS for each individual. Finally, larger and more comprehensive randomized controlled trials involving tDCS for chronic stroke recovery are underway that likely will shed light on how specific tDCS parameters, such as dose, affect stroke outcomes. The success of these collective efforts will determine whether tDCS for chronic stroke gains regulatory approval and becomes clinical practice in the future.

Neuromodulation for treatment-resistant depression: Functional network targets contributing to antidepressive outcomes.

Non-invasive brain stimulation is designed to target accessible brain regions that underlie many psychiatric disorders. One such method, transcranial magnetic stimulation (TMS), is commonly used in patients with treatment-resistant depression (TRD). However, for non-responders, the choice of an alternative therapy is unclear and often decided empirically without detailed knowledge of precise circuit dysfunction. This is also true of invasive therapies, such as deep brain stimulation (DBS), in which responses in TRD patients are linked to circuit activity that varies in each individual. If the functional networks affected by these approaches were better understood, a theoretical basis for selection of interventions could be developed to guide psychiatric treatment pathways. The mechanistic understanding of TMS is that it promotes long-term potentiation of cortical targets, such as dorsolateral prefrontal cortex (DLPFC), which are attenuated in depression. DLPFC is highly interconnected with other networks related to mood and cognition, thus TMS likely alters activity remote from DLPFC, such as in the central executive, salience and default mode networks. When deeper structures such as subcallosal cingulate cortex (SCC) are targeted using DBS for TRD, response efficacy has depended on proximity to white matter pathways that similarly engage emotion regulation and reward. Many have begun to question whether these networks, targeted by different modalities, overlap or are, in fact, the same. A major goal of current functional and structural imaging in patients with TRD is to elucidate neuromodulatory effects on the aforementioned networks so that treatment of intractable psychiatric conditions may become more predictable and targeted using the optimal technique with fewer iterations. Here, we describe several therapeutic approaches to TRD and review clinical studies of functional imaging and tractography that identify the diverse loci of modulation. We discuss differentiating factors associated with responders and non-responders to these stimulation modalities, with a focus on mechanisms of action for non-invasive and intracranial stimulation modalities. We advance the hypothesis that non-invasive and invasive neuromodulation approaches for TRD are likely impacting shared networks and critical nodes important for alleviating symptoms associated with this disorder. We close by describing a therapeutic framework that leverages personalized connectome-guided target identification for a stepwise neuromodulation paradigm.

Neurosurgery for psychiatric disorders: reviewing the past and charting the future.

Surgical techniques targeting behavioral disorders date back thousands of years. In this review, the authors discuss the history of neurosurgery for psychiatric disorders, starting with trephination in the Stone Age, progressing through the fraught practice of prefrontal lobotomy, and ending with modern neurosurgical techniques for treating psychiatric conditions, including ablative procedures, conventional deep brain stimulation, and closed-loop neurostimulation. Despite a tumultuous past, psychiatric neurosurgery is on the cusp of becoming a transformative therapy for patients with psychiatric dysfunction, with an ever-increasing evidence base suggesting reproducible and ethical therapeutic benefit.

The Role of Ethnic-Specific Gender Schemas in Ethnic Disparities in Adolescent Girls' Disruptive Behavior: A Preliminary Examination.

African American adolescent girls have evidenced higher levels of disruptive behavior than girls from other ethnic groups. However, most research focused on understanding disparities in these outcomes has been conducted without consideration of gender or has focused exclusively on boys. Yet, prior research suggests that anger and aggression are less gender-typed in African American youth than they are among youth from other ethnic backgrounds. The purpose of this preliminary investigation was to examine the extent to which ethnic-specific gender schemas about anger mediated the relationship between ethnicity and girls' disruptive behavior. Participants were 66 middle school girls (24.1 % African American, 46.3 % European American; Mage= 12.06). They completed measures of ethnic-specific gender schemas about anger, reactive and instrumental aggression, and classroom disruptive behavior. Results indicated that relative to girls from other ethnic groups, African American girls had higher levels of reactive aggression and classroom disruptive behavior, both of which are rooted in anger. In contrast, no ethnic difference was found for instrumental aggression, which is not connected to anger. Ethnic-specific gender schemas about anger at least partially accounted for ethnic differences in reactive aggression and classroom disruptive behavior. Findings highlight the importance of examining gender schemas specific to ethnicity as factors in ethnic disparities in behavioral outcomes among adolescent girls.

Piloting of the Just Say Know prevention program: a psychoeducational approach to translating the neuroscience of addiction to youth.

BACKGROUND: Substance use during adolescence can have a number of negative consequences and interfere with normal brain development. Given limited time and resources, brief group- and school-based prevention programs are an efficient strategy for educating youth about the effects of substance use on health outcomes. OBJECTIVES: To determine if a science-based, interactive substance prevention program could improve student knowledge and influence students' attitudes toward future substance use behaviors. METHODS: The Just Say Know program was given to 1,594 middle and high school students. The facilitator engaged students in an interactive, hour-long session covering brain basics and effects of substance use. Students completed an eight-item pre- and post-knowledge-based test to measure learning outcomes along with feedback questions about youths' attitudes toward substance use and the program. RESULTS: After the program, 94% of students reported that it provided helpful information; 92% reported it may influence their approach to substance use, with 76% specifying that they would delay or cut back on substance use. Knowledge-based test performance increased by 78%, with high schoolers displaying significantly higher scores than middle schoolers, but both showing similar improvements in scores. Students who reported higher levels of friends' substance use had smaller improvements from pre- to posttest. CONCLUSION: Results suggest Just Say Know, a scientifically-based prevention program, is effective in increasing adolescents' program based-knowledge, has the potential to affect youths' attitudes toward substance use, and is well-received. These findings provide preliminary evidence that a cost-effective, neuroscience-informed group prevention program might reduce or delay adolescents' future substance use.

Medical Cannabis Use among Adults in the Southeastern United States.

OBJECTIVES: To assess the self-reported reasons for medical cannabis use within the southeastern United States and compare recreational and medical cannabis users. METHODS: This study was a cross-sectional survey administered in 2017 through Amazon's Mechanical Turk and enrolled 432 adult, regular cannabis users. Measures included demographics, cannabis use characteristics, and medical reasons for cannabis use. RESULTS: Under half (47%) of respondents endorsed using cannabis for both medical and recreational reasons and 12% reported medical use only. The most commonly cited reasons for medical cannabis use were psychiatric and 60 unique medical conditions were listed. Recreational and medical users were similar on several measures of current use, but did vary in their use history, methods of use, and product knowledge. CONCLUSIONS: Despite state laws and conclusive scientific evidence to support medical cannabis use for certain conditions, cannabis is still used frequently for a range of medical issues. POLICY IMPLICATIONS: These data may assist healthcare providers in better understanding medical cannabis use in states with tightened restrictions and tailoring information to medical cannabis users about their specific conditions and prioritizing therapeutic options.

Tobacco and cannabis co-use and interrelatedness among adults.

Cannabis and tobacco co-use is prevalent, but consensus regarding the reasons for co-use among adults and the degree of interrelatedness between these substances is lacking. Reasons for co-use have been explored with younger users, but little data exists for more experienced users with entrenched patterns of co-use. The goal of this study was to examine characteristics and patterns of cannabis-tobacco co-use among adults in the Southeastern United States (US), where there is a legal landscape of generally restrictive cannabis legislation coupled with more permissive tobacco control compared to other US regions. Participants (N = 432) were regular cannabis users recruited through Amazon Mechanical Turk. Measures included demographics, patterns of cannabis and tobacco use, and reasons for co-use. Within this sample, 42% were current users of tobacco (n = 182). Cannabis-tobacco co-users were older and had more years of cannabis use than cannabis-only users. Among the co-using sub-sample, there was little consistency in the reasons for co-use, suggesting individual differences in the use of both substances. High levels of cannabis-tobacco interrelatedness (i.e., temporally concurrent use) were associated with smoking more cigarettes (tobacco) per day and greater nicotine dependence scores when compared to users with low levels of interrelatedness. Though these results are limited by a small sample size and generalizability issues, there were individual differences in cannabis-tobacco relatedness, which may be of importance when considering treatment strategies for cannabis, tobacco, or both. With additional research, personalized strategies adapted to cannabis-tobacco relatedness profiles among co-users may be warranted as a treatment strategy.

Tobacco and cannabis co-use: Drug substitution, quit interest, and cessation preferences.

The co-use of tobacco and cannabis is a common practice worldwide and carries with it substantial public health burden. Few interventions exist that target both substances and little is known about quit interest, treatment preferences, and drug substitution during past cessation attempts, which is critical to guide the development of treatment strategies. The goal of this study was to provide descriptive information regarding quit interest, treatment preferences, and perceived drug substitution among adult (age 18 +) cannabis-tobacco co-users. Participants (N = 282) from two independent survey samples (recruited from Amazon Mechanical Turk) from across the United States were combined. Among all participants, 57% were female, 79% were White, and average age was 33.31 (SD = 9.54) years old. Approximately 80% had tried to quit smoking cigarettes at least once, while 40% had tried to quit using cannabis at least once. Of those who tried to quit, 50% self-reported a perceived increase in their cannabis use during tobacco cessation and 62% self-reported a perceived increase in their tobacco use during cannabis cessation. Average quit interest (10-point scale) for cannabis was 2.39 (SD = 2.35) and for tobacco was 7.07 (SD = 2.90). Results of this study suggest that tobacco use should be addressed among cannabis-tobacco co-users, but interventions should consider lack of interest in cannabis cessation. Reduction-based strategies for cannabis use appear to be more acceptable to this nontreatment-seeking, co-using population. Drug substitution during quit attempts for one substance should be further explored as an important treatment consideration. (PsycINFO Database Record (c) 2019 APA, all rights reserved).