The neurobiology of addiction: the perspective from magnetic resonance imaging present and future

Large-scale network abnormality in behavioral addiction

BACKGROUND

Researchers have endeavored to ascertain the network dysfunction associated with behavioral addiction (BA) through the utilization of resting-state functional connectivity (rsFC). Nevertheless, the identification of aberrant patterns within large-scale networks pertaining to BA has proven to be challenging.

METHODS

Whole-brain seed-based rsFC studies comparing subjects with BA and healthy controls (HC) were collected from multiple databases. Multilevel kernel density analysis was employed to ascertain brain networks in which BA was linked to hyper-connectivity or hypo-connectivity with each prior network.

RESULTS

Fifty-six seed-based rsFC publications (1755 individuals with BA and 1828 HC) were included in the meta-analysis. The present study indicate that individuals with BAs exhibit (1) hypo-connectivity within the fronto-parietal network (FN) and hypo- and hyper-connectivity within the ventral attention network (VAN); (2) hypo-connectivity between the FN and regions of the VAN, hypo-connectivity between the VAN and regions of the FN and default mode network (DMN), hyper-connectivity between the DMN and regions of the FN; (3) hypo-connectivity between the reward system and regions of the sensorimotor network (SS), DMN and VAN; (4) hypo-connectivity between the FN and regions of the SS, hyper-connectivity between the VAN and regions of the SS.

CONCLUSIONS

These findings provide impetus for a conceptual framework positing a model of BA characterized by disconnected functional coordination among large-scale networks.

Changes in distinct brain systems identified with fMRI during smoking cessation treatment with varenicline: a review

BACKGROUND

Varenicline is considered one of the most effective treatment options for smoking cessation. Nonetheless, it is only modestly effective. A deeper comprehension of the effects of varenicline by means of the in-depth review of relevant fMRI studies may assist in paving the development of more targeted and effective treatments.

METHODOLOGY

A search of PubMed and Google Scholar databases was conducted with the keywords "functional magnetic resonance imaging" or "fMRI", and "varenicline". All peer-reviewed articles regarding the assessment of smokers with fMRI while undergoing treatment with varenicline and meeting the predefined criteria were included.

RESULTS

Several studies utilizing different methodologies and targeting different aspects of brain function were identified. During nicotine withdrawal, decreased mesocorticolimbic activity and increased amygdala activity, as well as elevated amygdala-insula and insula-default-mode-network functional connectivity are alleviated by varenicline under specific testing conditions. However, other nicotine withdrawal-induced changes, including the decreased reward responsivity of the ventral striatum, the bilateral dorsal striatum and the anterior cingulate cortex are not influenced by varenicline suggesting a task-dependent divergence in neurocircuitry activation. Under satiety, varenicline treatment is associated with diminished cue-induced activation of the ventral striatum and medial orbitofrontal cortex concomitant with reduced cravings; during the resting state, varenicline induces activation of the lateral orbitofrontal cortex and suppression of the right amygdala.

CONCLUSIONS

The current review provides important clues with regard to the neurobiological mechanism of action of varenicline and highlights promising research opportunities regarding the development of more selective and effective treatments and predictive biomarkers for treatment efficacy.

The resting-state brain activity signatures for addictive disorders

BACKGROUND

Addiction is a chronic and relapsing brain disorder. Despite numerous neuroimaging and neurophysiological studies on individuals with substance use disorder (SUD) or behavioral addiction (BEA), currently a clear neural activity signature for the addicted brain is lacking.

METHODS

We first performed systemic coordinate-based meta-analysis and partial least-squares regression to identify shared or distinct brain regions across multiple addictive disorders, with abnormal resting-state activity in SUD and BEA based on 46 studies (55 contrasts), including regional homogeneity (ReHo) and low-frequency fluctuation amplitude (ALFF) or fractional ALFF. We then combined Neurosynth, postmortem gene expression, and receptor/transporter distribution data to uncover the potential molecular mechanisms underlying these neural activity signatures.

FINDINGS

The overall comparison between addiction cohorts and healthy subjects indicated significantly increased ReHo and ALFF in the right striatum (putamen) and bilateral supplementary motor area, as well as decreased ReHo and ALFF in the bilateral anterior cingulate cortex and ventral medial prefrontal cortex, in the addiction group. On the other hand, neural activity in cingulate cortex, ventral medial prefrontal cortex, and orbitofrontal cortex differed between SUD and BEA subjects. Using molecular analyses, the altered resting activity recapitulated the spatial distribution of dopaminergic, GABAergic, and acetylcholine system in SUD, while this also includes the serotonergic system in BEA.

CONCLUSIONS

These results indicate both common and distinctive neural substrates underlying SUD and BEA, which validates and supports targeted neuromodulation against addiction.

FUNDING

This work was supported by the National Natural Science Foundation of China and Intramural Research Program of the National Institute on Drug Abuse, National Institutes of Health.

Using the Alcohol, Smoking and Substance Involvement Screening Test to predict substance-related hospitalisation after release from prison: A cohort study

BACKGROUND AND AIMS

Poor substance use-related health outcomes after release from prison are common. Identifying people at greatest risk of substance use and related harms post-release would help to target support at those most in need. The Alcohol Smoking and Substance Involvement Screening Test (ASSIST) is a validated substance use screener, but its utility in predicting substance-related hospitalisation post-release is unestablished. We measured whether screening for moderate/high-risk substance use on the ASSIST was associated with increased risk of substance-related hospitalisation.

DESIGN

A prospective cohort study.

SETTING

Prisons in Queensland and Western Australia.

PARTICIPANTS

Participants were incarcerated and within 6 weeks of expected release when recruited. A total of 2585 participants were followed up for a median of 873 days.

MEASUREMENTS

Baseline survey data were combined with linked unit record administrative hospital data. We used the ASSIST to assess participants for moderate/high-risk cannabis, methamphetamine and heroin use in the 3 months prior to incarceration. We used International Classification of Diseases (ICD) codes to identify substance-related hospitalisations during follow-up. We compared rates of substance-related hospitalisation between those classified as low/no-risk and moderate/high-risk on the ASSIST for each substance. We estimated adjusted hazard ratios (aHR) by ASSIST risk group for each substance using Weibull regression survival analysis allowing for multiple failures.

FINDINGS

During follow-up, 158 (6%) participants had cannabis-related, 178 (7%) had opioid-related and 266 (10%) had methamphetamine-related hospitalisation. The hazard rates of substance-related hospitalisation after prison were significantly higher among those who screened moderate/high-risk compared with those screening low risk on the ASSIST for cannabis (aHR 2.38, 95% confidence interval [CI] 1.74, 3.24), methamphetamine (aHR 2.23, 95%CI 1.75, 2.84) and heroin (aHR 5.79, 95%CI 4.41, 7.60).

CONCLUSIONS

Incarcerated people with an Alcohol Smoking and Substance Involvement Screening Test (ASSIST) screening of moderate/high-risk substance use appear to have a significantly higher risk of post-release substance-related hospitalisation than those with low risk. Administering the ASSIST during incarceration may inform who has the greatest need for substance use treatment and harm reduction services in prison and after release from prison.

The predictive validity of the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) for moderate- to high-risk cannabis, methamphetamine and opioid use after release from prison

BACKGROUND AND AIMS

Illicit substance use is common among people entering prisons, as is returning to substance use after release from prison. We aimed to assess the predictive validity of the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) for returning to substance use after release from prison.

DESIGN

A longitudinal design with baseline survey conducted between 2008 and 2010 in the 6 weeks before expected prison release and up to three follow-up surveys in the 6 months after release.

SETTING

Prisons in Queensland, Australia.

PARTICIPANTS

A total of 1054 adults within 6 weeks of expected release from prison.

MEASUREMENTS

The ASSIST was used to assess problematic use of cannabis, methamphetamine, heroin and other non-prescribed opioids in the 3 months before incarceration. Post-incarceration substance use was measured at 1, 3 and 6 months after release. We calculated the area under the receiver operating characteristic curve (AUROC) and the optimal ASSIST cut-off score for each substance, using Youden's index (J).

FINDINGS

Forty-one per cent (n = 434) of the cohort reported any substance use during follow-up: 33% (n = 344) used cannabis, 20% (n = 209) methamphetamine, 10% (n = 109) heroin and 9% (n = 97) illicit other opioids. The optimal ASSIST cut-off score was ≥ 4 for heroin, methamphetamine and cannabis and ≥ 1 for other opioids. Using these cut-offs, the AUROC was highest for heroin in predicting both any use (AUROC = 0.82) and weekly use (AUROC = 0.88) in the past 4 weeks. AUROCs for other drugs ranged from 0.73 to 0.79.

CONCLUSIONS

The ASSIST shows promise as an accurate and potentially scalable tool that may be useful for predicting a return to substance use after release from prison and could inform service delivery. The substantial rates of returning to substance use after release from prison suggest that prison serves to interrupt rather than cease substance use.

Neurobiological mechanisms and related clinical treatment of addiction: a review

Drug addiction or substance use disorder (SUD), has been conceptualized as a three-stage (i.e. binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation/craving) recurring cycle that involves complex changes in neuroplasticity, reward, motivation, desire, stress, memory, and cognitive control, and other related brain regions and brain circuits. Neuroimaging approaches, including magnetic resonance imaging, have been key to mapping neurobiological changes correlated to complex brain regions of SUD. In this review, we highlight the neurobiological mechanisms of these three stages of addiction. The abnormal activity of the ventral tegmental, nucleus accumbens, and caudate nucleus in the binge/intoxication stage involve the reward circuit of the midbrain limbic system. The changes in the orbitofrontal cortex, dorsolateral prefrontal cortex, amygdala, and hypothalamus emotional system in the withdrawal/negative affect stage involve increases in negative emotional states, dysphoric-like effects, and stress-like responses. The dysregulation of the insula and prefrontal lobes is associated with craving in the anticipation stage. Then, we review the present treatments of SUD based on these neuroimaging findings. Finally, we conclude that SUD is a chronically relapsing disorder with complex neurobiological mechanisms and multimodal stages, of which the craving stage with high relapse rate may be the key element in treatment efficacy of SUD. Precise interventions targeting different stages of SUD and characteristics of individuals might serve as a potential therapeutic strategy for SUD.

Ventral striatal subregional dysfunction in late-life grief: Relationships with yearning and depressive symptoms

Bereaved older adults experiencing high grief in the first year after an attachment loss is at increased risk for prolonged grief disorder (PGD) via unknown mechanisms. Yearning, a core grief symptom, is linked to the ventral striatal (VS) brain function, but the role of this neuronal system in late-life grief is poorly understood. As a first step, we examined the VS subregional abnormalities associated with multidimensional symptoms in bereaved elders during the first year post-loss. Sixty-five bereaved elders completed clinical assessments within 13 months post-loss. Ventral caudate (VCau) and nucleus accumbens (NAcc) functional connectivity (FC) was assessed using seed-based resting-state functional MRI. VCau and NAcc FC differences between high (inventory of complicated grief [ICG] score≥30; n = 35) and low (ICG score<30; n = 30) grief, and the relationships between ventral striatal subregional FC and clinical measures (yearning and depressive symptoms) were assessed after covariate adjustments (α < 0.05; 3dClustSim corrected). Relative to low grief participants, those with high grief showed higher FC between VCau and the medial prefrontal, orbitofrontal, and subgenual cingulate cortices. VCau FC abnormalities positively correlated with yearning (r2 = 0.24, p < 0.001). In contrast, FC between VCau and temporoparietal junction negatively correlated with depressive symptoms, a commonly co-occurring symptom (r2 = 0.37, p < 0.001). The FC between NAcc and insula/striatum positively correlated with yearning (r2 = 0.35, p < 0.001); no other NAcc FC findings were seen in the full sample. In women, higher FC between the NAcc and bilateral posterior cingulate, precuneus, and visual areas were found in those with high, relative to low grief symptoms. Distinct VS subregional abnormalities associate with yearning and depressive symptoms in bereaved elders. Whether ventral striatal dysfunction correlates with PGD development and/or worsening depression remains to be elucidated.

A Systematic Review on Common and Distinct Neural Correlates of Risk-taking in Substance-related and Non-substance Related Addictions

Both substance-related as well as non-substance-related addictions may include recurrent engagement in risky actions despite adverse outcomes. We here apply a unified approach and review task-based neuroimaging studies on substance-related (SRAs) and non-substance related addictions (NSRAs) to examine commonalities and differences in neural correlates of risk-taking in these two addiction types. To this end, we conducted a systematic review adhering to the PRISMA guidelines. Two databases were searched with predefined search terms to identify neuroimaging studies on risk-taking tasks in individuals with addiction disorders. In total, 19 studies on SRAs (comprising a total of 648 individuals with SRAs) and 10 studies on NSRAs (comprising a total of 187 individuals with NSRAs) were included. Risk-related brain activation in SRAs and NSRAs was summarized individually and subsequently compared to each other. Results suggest convergent altered risk-related neural processes, including hyperactivity in the OFC and the striatum. As characteristic for both addiction types, these brain regions may represent an underlying mechanism of suboptimal decision-making. In contrast, decreased DLPFC activity may be specific to SRAs and decreased IFG activity could only be identified for NSRAs. The precuneus and posterior cingulate show elevated activity in SRAs, while findings regarding these areas were mixed in NSRAs. Additional scarce evidence suggests decreased ventral ACC activity and increased dorsal ACC activity in both addiction types. Associations between identified activation patterns with drug use severity underpin the clinical relevance of these findings. However, this exploratory evidence should be interpreted with caution and should be regarded as preliminary. Future research is needed to evaluate the findings gathered by this review.

Brain network dysfunctions in addiction: a meta-analysis of resting-state functional connectivity

Resting-state functional connectivity (rsFC) provides novel insights into variabilities in neural networks associated with the use of addictive drugs or with addictive behavioral repertoire. However, given the broad mix of inconsistent findings across studies, identifying specific consistent patterns of network abnormalities is warranted. Here we aimed at integrating rsFC abnormalities and systematically searching for large-scale functional brain networks in substance use disorder (SUD) and behavioral addictions (BA), through a coordinate-based meta-analysis of seed-based rsFC studies. A total of fifty-two studies are eligible in the meta-analysis, including 1911 SUD and BA patients and 1580 healthy controls. In addition, we performed multilevel kernel density analysis (MKDA) for the brain regions reliably involved in hyperconnectivity and hypoconnectivity in SUD and BA. Data from fifty-two studies showed that SUD was associated with putamen, caudate and middle frontal gyrus hyperconnectivity relative to healthy controls. Eight BA studies showed hyperconnectivity clusters within the putamen and medio-temporal lobe relative to healthy controls. Altered connectivity in salience or emotion-processing areas may be related to dysregulated affective and cognitive control-related networks, such as deficits in regulating elevated sensitivity to drug-related stimuli. These findings confirm that SUD and BA might be characterized by dysfunctions in specific brain networks, particularly those implicated in the core cognitive and affective functions. These findings might provide insight into the development of neural mechanistic biomarkers for SUD and BA.

Problematic social media use is associated with the evaluation of both risk and ambiguity during decision making

BACKGROUND AND AIMS

People can engage in excessive, maladaptive use of social media platforms. This problematic social media use mirrors substance use disorders with regard to symptoms and certain behavioral situations. For example, individuals with substance use disorders demonstrate aberrations in risk evaluations during decision making, and initial research on problematic social media use has revealed similar findings. However, these results concerning problematic social media use have been clouded by tasks that involve learning and that lack a clear demarcation between risky and ambiguous decision making. Therefore, we set out to specifically determine the relationship between problematic social media use and decision making under both risk and ambiguity, in the absence of learning.

METHODS

We assessed each participant's (N = 90) self-reported level of problematic social media use. We then had them perform the wheel of fortune task, which has participants make choices between a sure option or either a risky or ambiguous gamble. In this way, the task isolates decisions made under risk and ambiguity, and avoids trial-to-trial learning. Results: We found that the greater an individual's problematic social media use, the more often that individual choses high-risk gambles or ambiguous gambles, regardless of the degree of ambiguity.

DISCUSSION AND CONCLUSIONS

Our findings indicate that greater problematic social media use is related to a greater affinity for high-risk situations and overall ambiguity. These findings have implications for the field, specifically clarifying and extending the extant literature, as well as providing future avenues for research.

History and Status of Prolonged Grief Disorder as a Psychiatric Diagnosis

Prolonged grief disorder (PGD) is a diagnostic entity now included in the International Classification of Diseases 11th Revision (ICD-11) and soon to appear in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition, text revision (DSM-5-TR). A characteristic feature of PGD is distressing, disabling yearning that persists a year or more after the loss. Other characteristic symptoms include disbelief and lack of acceptance of the loss, emotional detachment from others since the loss, loneliness, identity disturbance, and sense of meaninglessness. In this review, we detail psychiatric views on grief and their evolution over the twentieth century. We then discuss the development of diagnostic formulations for disordered grief, which culminated in PGD's status as a mental disorder in the DSM. After summarizing recent evidence that may suggest that PGD is linked to the neural reward system, we suggest further areas of research. In particular, we note the need for studies that extend the evidence base concerning PGD across cultural and sociodemographic boundaries and that investigate novel treatments.

Evaluation of Internet Gaming Disorder, Social Media Addiction, and Levels of Loneliness in Adolescents and Youth with Substance Use

Substance use and addictive disorders are among the most significant public health concerns, particularly during adolescence. The current study aims to investigate internet gaming disorder, social media addiction, and loneliness levels in adolescents and youths with substance use. Methods: The study group consisted of 93 adolescents and youths aged 15-24 who presented to the Alcohol and Substance Addiction Research and Application Center or the Child and Adolescent Mental Health and Diseases outpatient clinic for substance use. Ninety-one healthy volunteers who did not use substances during any period of their lives participated as a control group. The participants fulfilled the Social Media Addiction Scale (SMAS), Internet Gaming Disorder Scale - Short-Form (IGDS9-SF), UCLA Loneliness Scale (UCLA-LS), and Drug Use Disorders Identification Test - Extended (DUDIT-E). Results: The symptoms of internet gaming disorder were significantly lower in the patient group compared with the control group. Although it was not significant, social media addiction was higher in the patient group than in the control group. The experience of loneliness was significantly higher in the patient group than in the control group. A significant negative correlation was found between treatment motivation and loneliness. Conclusions: School guidance teachers should monitor children who do not have friends or are lonely and be aware of the potential for substance use because it can emerge as a method of coping with the feeling of loneliness among adolescents. In future studies, investigating comprehensive factors contributing to different addictive behaviors may help to clarify the co-occurrence.

The neurobiological reward system in Prolonged Grief Disorder (PGD): A systematic review

Prolonged Grief Disorder (PGD) is a debilitating condition affecting between 7% and 10% of bereaved individuals. Past imaging and psychological studies have proposed links between PGD's characteristic symptoms - in particular, profound yearning - and the neural reward system. We conducted a systematic review to investigate this connection. On December 19, 2019, we searched six bibliographic databases for data on the neurobiology of grief and disordered grief. We excluded studies of the hypothalamic-pituitary-adrenal (HPA) axis, animal studies, and reviews. After abstract and full-text screening, twenty-four studies were included in the final review. We found diverse evidence for the activation of several reward-related regions of the brain in PGD. The data reviewed suggest that compared to normative grief, PGD involves a differential pattern of activity in the amygdala and orbitofrontal cortex (OFC); likely differential activity in the posterior cingulate cortex (PCC), rostral or subgenual anterior cingulate cortex (ACC), and basal ganglia overall, including the nucleus accumbens (NAc); and possible differential activity in the insula. It also appears that oxytocin signaling is altered in PGD, though the exact mechanism is unclear. Our findings appear to be consistent with, though not confirmative of, conceptualizing PGD as a disorder of reward, and identify directions for future research.

Mind over Matter: Testing the Efficacy of an Online Randomized Controlled Trial to Reduce Distraction from Smartphone Use

Evidence suggests a growing call for the prevention of excessive smartphone and social media use and the ensuing distraction that arises affecting academic achievement and productivity. A ten-day online randomized controlled trial with the use of smartphone apps, engaging participants in mindfulness exercises, self-monitoring and mood tracking, was implemented amongst UK university students (n = 143). Participants were asked to complete online pre- and post-intervention assessments. Results indicated high effect sizes in reduction of smartphone distraction and improvement scores on a number of self-reported secondary psychological outcomes. The intervention was not effective in reducing habitual behaviours, nomophobia, or time spent on social media. Mediation analyses demonstrated that: (i) emotional self-awareness but not mindful attention mediated the relationship between intervention effects and smartphone distraction, and (ii) online vigilance mediated the relationship between smartphone distraction and problematic social media use. The present study provides preliminary evidence of the efficacy of an intervention for decreased smartphone distraction and highlights psychological processes involved in this emergent phenomenon in the smartphone literature. Online interventions may serve as complementary strategies to reduce distraction levels and promote insight into online engagement. More research is required to elucidate the mechanisms of digital distraction and assess its implications in problematic use.

Structural and functional correlates of smartphone addiction

Popularity and availability of smartphones have dramatically increased in the past years. This trend is accompanied by increased concerns regarding potentially adverse effects of excessive smartphone use, particularly with respect to physical and mental health. Recently, the term "smartphone addiction" (SPA) has been introduced to describe smartphone-related addictive behavior and associated physical and psychosocial impairment. Here, we used structural and functional magnetic resonance imaging (MRI) at 3 T to investigate gray matter volume (GMV) and intrinsic neural activity in individuals with SPA (n = 22) compared to a control group (n = 26). SPA was assessed using the Smartphone Addiction Inventory (SPAI), GMV was investigated by means of voxel-based morphometry, and intrinsic neural activity was measured by the amplitude of low frequency fluctuations (ALFF). Compared to controls, individuals with SPA showed lower GMV in left anterior insula, inferior temporal and parahippocampal cortex (p < 0.001, uncorrected for height, followed by correction for spatial extent). Lower intrinsic activity in SPA was found in the right anterior cingulate cortex (ACC). A significant negative association was found between SPAI and both ACC volume and activity. In addition, a significant negative association between SPAI scores and left orbitofrontal GMV was found. This study provides first evidence for distinct structural and functional correlates of behavioral addiction in individuals meeting psychometric criteria for SPA. Given their widespread use and increasing popularity, the present study questions the harmlessness of smartphones, at least in individuals that may be at increased risk for developing smartphone-related addictive behaviors.

Reinforcer Pathology: Implications for Substance Abuse Intervention

The rate at which individuals discount future rewards (i.e., discounting rate) is strongly associated with their propensity for substance abuse as well as myriad other negative health behaviors. An excessive preference for immediately available rewards suggests a shortened time horizon in which immediate rewards are overvalued and future, potentially negative consequences are undervalued. This review outlines Reinforcer Pathology Theory (i.e., the interaction between excessive preference for immediately available rewards and the overvaluation of a particular commodity that offers brief, intense reinforcement), its neurobiological/behavioral underpinnings, and its implications for treating substance use disorders. In doing so, the current review provides an overview of a variety of ways in which interventions have been used to manipulate aspects of reinforcer pathology in an individual, including narrative theory, framing manipulations, and neuromodulation (e.g., working memory training, TMS) which may serve as promising avenues for the modulation of the temporal window and/or valuation of reinforcers.

Executive Impairment in Alcohol Use Disorder Reflects Structural Changes in Large-Scale Brain Networks: A Joint Independent Component Analysis on Gray-Matter and White-Matter Features

Alcohol Use Disorder (AUD) entails chronic effects on brain structure. Neurodegeneration due to alcohol toxicity is a neural signature of executive impairment typically observed in AUD, previously related to both gray-matter volume/density and white-matter abnormalities. Recent studies highlighted the role of meso-cortico-limbic structures supporting the salience and executive networks, in which the extent of neurostructural damage is significantly related to patients’ executive performance. Here we aim to integrate multimodal information on gray-matter and white-matter features with a multivariate data-driven approach (joint Independent Component Analysis, jICA), and to assess the relationship between the extent of damage in the resulting neurostructural superordinate components and executive profile in AUD. Twenty-two AUD patients and 18 matched healthy controls (HC) underwent a Magnetic Resonance Imaging (MRI) protocol, alongside clinical and neuropsychological examinations. We ran jICA on five neurostructural features, including gray-matter density and different diffusion tensor imaging metrics. We extracted 12 Independent Components (ICs) and compared the resulting mixing coefficients in patients vs. HC. Finally, we correlated significant ICs with executive and clinical variables. One out of 12 ICs (IC11) discriminated patients from healthy controls and correlated positively both with executive performance in all subjects, and with lifetime duration of alcohol abuse in patients. In line with previous related evidence, this component involved widespread gray-matter and white-matter patterns including key nodes and fiber tracts of salience, default-mode and central executive networks. These findings highlighted the role of multivariate data integration as a valuable approach revealing superordinate hallmarks of neural changes related to cognition in neurological and psychiatric populations.

Love is a physiological motivation (like hunger, thirst, sleep or sex)

The multitude of terms associated with love has given rise to a false perception of love. In this paper, only maternal and romantic love are considered. Love is usually regarded as a feeling, motivation, addiction, passion, and, above all, an emotion. This confusion has consequences in the lives of human beings, leading not only to divorces, suicides, femicides but possibly also to a number of mental illnesses and suffering. Therefore, it is crucial to first clarify what is meant by emotion, motivation and love. This work aims to finally place love within the category of physiological motivations, such as hunger, thirst, sleep, or sex, on the basis that love is also essential for human survival, especially in childhood. Love is presented from an evolutionary perspective. Some other similarities between love and other physiological motivations are pointed out, such as its importance for appropriate human development, both its ontogeny and its permanence, and the long-lasting consequences of abuse and neglect. There are summarized reasons that account for this, such as the fact that physiological motivations are essential for survival and that love is an essential motivation for the survival of human offspring. Other reasons are that minimum changes in the quantity and quality of love alters development, that there can be a variety of neurophysiological and behavioural states within a motivation, and that motivations (also love) appear and change throughout development. Also, motivations and love sometimes may lead to an addictive behaviour. Finally, it is recognized that once physiological motivations (and love) appear, they become permanent. In a third section, some potential social, cultural, clinical and scientific consequences of the proposed consideration of love as a motivation are discussed. Accordingly, love's recognition as a motivation in the clinical field would imply a better understanding of its disorders and its inclusion in classifications manuals such as The Diagnostic and Statistical Manual of Mental Disorders (DSM), or in the International Classification of Diseases (ICD). Considering love as a motivation rather than an emotion could also impact the results of scientific research (an example is included). A comprehensive understanding of these questions could potentially allow for a new therapeutic approach in the treatment of mental illness, while offering an all-inclusive evolutionary explanation of cultural phenomena such as the origin and diffusion of both language and art. Love should be understood as a physiological motivation, like hunger, sleep or sex, and not as an emotion as it is commonly considered.

Substance abuse and white matter: Findings, limitations, and future of diffusion tensor imaging research

Individuals who abuse substances often differ from nonusers in their brain structure. Substance abuse and addiction is often associated with atrophy and pathology of grey matter, but much less is known about the role of white matter, which constitutes over half of human brain volume. Diffusion tensor imaging (DTI), a method for non-invasively estimating white matter, is increasingly being used to study addiction and substance abuse. Here we review recent DTI studies of major substances of abuse (alcohol, opiates, cocaine, cannabis, and nicotine substance abuse) to examine the relationship, specificity, causality, and permanence of substance-related differences in white matter microstructure. Across substance, users tended to exhibit differences in the microstructure of major fiber pathways, such as the corpus callosum. The direction of these differences, however, appeared substance-dependent. The subsample of longitudinal studies reviewed suggests that substance abuse may cause changes in white matter, though it is unclear to what extent such alterations are permanent. While collectively informative, some studies reviewed were limited by methodological and technical approach. We therefore also provide methodological guidance for future research using DTI to study substance abuse.

Excessive social media users demonstrate impaired decision making in the Iowa Gambling Task

BACKGROUND AND AIMS

Online social networking sites (SNSs) like Facebook provide users with myriad social rewards. These social rewards bring users back to SNSs repeatedly, with some users displaying maladaptive, excessive SNS use. Symptoms of this excessive SNS use are similar to symptoms of substance use and behavioral addictive disorders. Importantly, individuals with substance use and behavioral addictive disorders have difficulty making value-based decisions, as demonstrated with paradigms like the Iowa Gambling Task (IGT); however, it is currently unknown if excessive SNS users display the same decision-making deficits. Therefore, in this study, we aimed to investigate the relationship between excessive SNS use and IGT performance.

METHODS

We administered the Bergen Facebook Addiction Scale (BFAS) to 71 participants to assess their maladaptive use of the Facebook SNS. We next had them perform 100 trials of the IGT to assess their value-based decision making.

RESULTS

We found a negative correlation between BFAS score and performance in the IGT across participants, specifically over the last block of 20 trials. There were no correlations between BFAS score and IGT performance in earlier blocks of trials.

DISCUSSION

Our results demonstrate that more severe, excessive SNS use is associated with more deficient value-based decision making. In particular, our results indicate that excessive SNS users may make more risky decisions during the IGT task.

CONCLUSION

This result further supports a parallel between individuals with problematic, excessive SNS use, and individuals with substance use and behavioral addictive disorders.

Excessive discounting of delayed reinforcers as a trans-disease process: Update on the state of the science

Delay discounting, or the process by which reinforcers lose value with delay to their receipt, has been identified as a trans-disease process underlying addiction, other disorders, and maladaptive health behaviors. Delay discounting has been identified as an endophenotype for multiple psychiatric disorders including substance use disorder, ADHD, and major depressive disorder, with this endophenotype being linked to deficits in dopaminergic and serotonergic neurotransmission. In addition, neuroanatomical and neurophysiological deficits in areas of the executive and impulsive systems have been associated with both steeper discounting and substance use disorders. Delay discounting constitutes a novel target for interventions to change health behaviors. A new theory, termed reinforcer pathology, has been developed uniting these findings and setting the stage for future research.

Methamphetamine use and cognitive function: A systematic review of neuroimaging research

BACKGROUND

Long-term use of MA has been associated with cognitive dysfunction in several domains. Neuroimaging studies have also reported structural, metabolic, and functional changes in MA users. However, no systematic review has been conducted on those studies in MA users that combined neuroimaging and cognitive tasks.

METHODS

This article systematically reviews correlation between brain imaging measures and cognitive performance in subjects with current and previous history of MA use. Findings are categorized based on cognitive domain.

RESULTS

MA users performed more poorly than controls in all cognitive domains (psychomotor, working memory, attention, cognitive control, and decision- making) and a positive correlation has been repeatedly observed between performance and brain measures (regional volume/density, blood flow, glucose metabolism, FA value, NAA level, and activation) in MA users. Performance in cognitive control was consistently reported to show relationship with brain measures in the PFC and ACC, while decision- making consistently showed correlation with brain measures in the PFC, ACC, and striatum.

CONCLUSIONS

There is solid evidence for brain- behavior relationship in cognitive functioning in MA users, particularly in cognitive control and decision-making. More research with correlation analysis between brain-behavior and MA use parameters is strongly encouraged.

Dopamine and addiction: what have we learned from 40 years of research

Among the neurotransmitters involved in addiction, dopamine (DA) is clearly the best known. The critical role of DA in addiction is supported by converging evidence that has been accumulated in the last 40 years. In the present review, first we describe the dopaminergic system in terms of connectivity, functioning and involvement in reward processes. Second, we describe the functional, structural, and molecular changes induced by drugs within the DA system in terms of neuronal activity, synaptic plasticity and transcriptional and molecular adaptations. Third, we describe how genetic mouse models have helped characterizing the role of DA in addiction. Fourth, we describe the involvement of the DA system in the vulnerability to addiction and the interesting case of addiction DA replacement therapy in Parkinson's disease. Finally, we describe how the DA system has been targeted to treat patients suffering from addiction and the result obtained in clinical settings and we discuss how these different lines of evidence have been instrumental in shaping our understanding of the physiopathology of drug addiction.

Prevalence of pathological and maladaptive Internet use and the association with depression and health-related quality of life in Japanese elementary and junior high school-aged children

PURPOSE

Pathological Internet use has been predominantly studied in junior high/middle school-aged or older children; data from elementary/primary school-aged children, however, are scarce. The current study aimed to examine the prevalence of problematic Internet use, including pathological and maladaptive Internet use, in elementary and junior high school-aged children and the relationships between problematic Internet use and mental health problems and health-related quality of life.

METHODS

The survey was conducted among children who attend national and public elementary and junior high schools in a medium-sized city in Japan; data were received from 3845 elementary school-aged and 4364 junior high school-aged children.

RESULTS

Based on the Young's Diagnostic Questionnaire score, the prevalence of pathological and maladaptive Internet use was 3.6% and 9.4% and 7.1% and 15.8% in elementary and junior high school-aged children, respectively. The prevalence of problematic Internet use, including pathological and maladaptive Internet use, consistently increased from the 4th grade to the 8th grade. In addition, the prevalence sharply increased between the 7th grade and the 8th grade. Our study revealed that children with pathological and maladaptive Internet use exhibited more severe depression and decreased health-related quality of life than those with adaptive Internet use.

CONCLUSIONS

Our results demonstrated that pathological Internet use is not uncommon even in elementary school-aged children and that those with pathological and maladaptive Internet use have severe mental health problems and decreased health-related quality of life, supporting the importance of providing these children with educational and preventive interventions against problematic Internet use and associated risk factors.

tDCS in Addiction and Impulse Control Disorders

The study of addiction and impulsion control disorders has shown that behaviors of seeking and consumption of addictive substances are subserved by neurobiological alterations specifically related to brain networks for reward, stress, and executive control, representing the brain's adaptation to the continued use of an addictive substance. In parallel, studies using neuromodulation techniques such as transcranial direct current stimulation (tDCS) have demonstrated promising effects in modulating cognitive and motor functions. This review aims to describe the neurobiology of addiction and some of the most relevant cognitive models of addictive behavior and to clarify how tDCS application modulates the intake and craving for several addictive substances, such as food, alcohol, nicotine, cocaine, crack, methamphetamine, and cannabis. We also discuss the positive and null outcomes of the use of this neuromodulatory technique in the treatment of addiction disorders resulting from the use of these substances. The reviewed findings lead us to conclude that tDCS interventions hold several promising clinical avenues in addiction and impulsive control. However, methodological investigations are necessary for undercover optimal parameters before implementing its clinical application.

PPAR-gamma agonist pioglitazone modifies craving intensity and brain white matter integrity in patients with primary cocaine use disorder: a double-blind randomized controlled pilot trial

BACKGROUND AND AIMS

Pioglitazone (PIO), a potent agonist of PPAR-gamma, is a promising candidate treatment for cocaine use disorder (CUD). We tested the effects of PIO on targeted mechanisms relevant to CUD: cocaine craving and brain white matter (WM) integrity. Feasibility, medication compliance and tolerability were evaluated.

DESIGN

Two-arm double-blind randomized controlled proof-of-concept pilot trial of PIO or placebo (PLC).

SETTING

Single-site out-patient treatment research clinic in Houston, TX, USA.

PARTICIPANTS

Thirty treatment-seeking adults, 18 to 60 years old, with CUD. Eighteen participants (8 = PIO; 10 = PLC) completed diffusion tensor imaging (DTI) of WM integrity at pre-/post-treatment.

INTERVENTION

Study medication was dispensed at thrice weekly visits along with once-weekly cognitive behavioral therapy for 12 weeks.

MEASUREMENTS

Measures of target engagement mechanisms of interest included cocaine craving assessed by the Brief Substance Craving Scale (BSCS), the Obsessive Compulsive Drug Use Scale (OCDUS), a visual analog scale (VAS) and change in WM integrity. Feasibility measures included number completing treatment, medication compliance (riboflavin detection) and tolerability (side effects, serious adverse events).

FINDINGS

Target engagement change in mechanisms of interest, defined as a ≥ 0.75 Bayesian posterior probability of an interaction existing favoring PIO over PLC, was demonstrated on measures of craving (BSCS, VAS) and WM integrity indexed by fractional anisotropy (FA) values. Outcomes indicated greater decrease in craving and greater increase in FA values in the PIO group. Feasibility was demonstrated by high completion rates among those starting treatment (21/26 = 80%) and medication compliance (≥ 80%). There were no reported serious adverse events for PIO.

CONCLUSIONS

Compared with placebo, patients receiving pioglitazone show a higher likelihood of reduced cocaine craving and improved brain white matter integrity as a function of time in treatment. Pioglitazone shows good feasibility as a treatment for cocaine use disorder.

The neurobiology of addiction: the perspective from magnetic resonance imaging present and future

BACKGROUND AND AIMS

Addiction is associated with severe economic and social consequences and personal tragedies, the scientific exploration of which draws upon investigations at the molecular, cellular and systems levels with a wide variety of technologies. Magnetic resonance imaging (MRI) has been key to mapping effects observed at the microscopic and mesoscopic scales. The range of measurements from this apparatus has opened new avenues linking neurobiology to behaviour. This review considers the role of MRI in addiction research, and what future technological improvements might offer.

METHODS

A hermeneutic strategy supplemented by an expansive, systematic search of PubMed, Scopus and Web of Science databases, covering from database inception to October 2015, with a conjunction of search terms relevant to addiction and MRI. Formal meta-analyses were prioritized.

RESULTS

Results from methods that probe brain structure and function suggest frontostriatal circuitry disturbances within specific cognitive domains, some of which predict drug relapse and treatment response. New methods of processing imaging data are opening opportunities for understanding the role of cerebral vasculature, a global view of brain communication and the complex topology of the cortical surface and drug action. Future technological advances include increases in MRI field strength, with concomitant improvements in image quality.

CONCLUSIONS

The magnetic resonance imaging literature provides a limited but convergent picture of the neurobiology of addiction as global changes to brain structure and functional disturbances to frontostriatal circuitry, accompanied by changes in anterior white matter.