Intra-individual changes in Stroop-related activations linked to cigarette abstinence in adolescent tobacco smokers: Preliminary findings

BACKGROUND

Adolescence is a crucial time for initiation of tobacco-smoking. Developing more effective treatment interventions for tobacco-smoking in youth is therefore critical to reduce smoking rates in both adolescent and adult populations. Elucidation of the neural mechanisms of successful behavioral change (abstinence) will allow for improvement of therapies based on known brain mechanisms.

METHODS

Twenty-one adolescent tobacco-smokers (14-19 years) participated in functional magnetic resonance imaging (fMRI) during performance of a cognitive control (Stroop) task prior to randomization to smoking cessation treatment (trial of combined nicotine replacement therapy/placebo and contingency management for attendance/abstinence; NCT01145001). Fourteen adolescents also participated in fMRI scanning following completion of the six-week trial. fMRI data were analyzed using random-effects models in SPM12. Paired t-tests were used to identify group-level changes (main effect of treatment exposure) in neural functional responses. Regression models were used to identify individual-level changes associated with treatment-outcomes (percent days abstinent, maximum days of consecutive abstinence).

RESULTS

Main effects of Stroop task performance (contrast of incongruent versus congruent trials) were seen across a priori ROIs at both pre- and post-treatment (pFWE<0.05). At the group-level, no changes in neural responses were found following treatment. However, intra-individual reductions in Stroop-related activity (within the insula and anterior cingulate) were positively associated with measures of smoking abstinence during treatment (pFWE<0.05).

CONCLUSIONS

Abstinence from tobacco during smoking cessation treatment among adolescents is associated with cognitive-control related reductions in neural activity within specific regions (anterior cingulate, insula), suggesting that increases in cognitive efficiency may underlie optimal treatment responses in this population.

Anticipatory reward processing among cocaine-dependent individuals with and without concurrent methadone-maintenance treatment: Relationship to treatment response

BACKGROUND

Cocaine dependence among opioid-dependent methadone-maintained individuals is a significant public health problem and is particularly challenging to treat. The neurobiology of this clinically complex population has not been previously assessed using fMRI.

METHODS

fMRI data from cocaine-dependent, methadone-maintained (CD-MM) patients (n=24), cocaine-dependent (CD) patients (n=20) and healthy comparison (HC) participants (n=21) were acquired during monetary incentive delay task performance. All patients were scanned prior to treatment for cocaine dependence. Between-group differences in anticipatory reward and loss processing were assessed using whole-brain ANOVAs in SPM12 (pFWE<0.05). Correlations between durations of abstinence during treatment and BOLD responses within the insula and caudate were also explored.

RESULTS

Main effects of diagnostic group, primarily involving decreased BOLD responses among CD-MM patients in comparison to HCs, were observed during anticipatory reward and loss processing within regions of posterior cingulate cortex, precuneus, inferior frontal gyrus and dorsolateral prefrontal cortex. BOLD responses within the right caudate were negatively associated with percentage of cocaine-negative urines during treatment among CD-MM patients, but not among non-methadone-maintained CD patients.

CONCLUSIONS

These data suggest neurofunctional differences that may be related to treatment outcomes for behavioral therapies between cocaine-dependent individuals with and without methadone-maintenance treatment. These findings may relate to differences in treatment efficacies and to the elevated relapse rates observed in methadone-maintained populations.

White matter development and tobacco smoking in young adults: A systematic review with recommendations for future research

BACKGROUND

Adolescence and young adulthood are critical vulnerability periods for initiation of tobacco smoking. White matter development is ongoing during this time and may be influenced by exposure to nicotine. Synthesis of findings from diffusion tensor imaging (DTI) studies of adolescent and young adult smokers may be helpful in understanding the relationship between neurodevelopment and initiation and progression of tobacco-use behaviors and in guiding further research.

METHODS

A systematic literature review was conducted to identify DTI studies comparing adolescent and young adult (mean age <30 years) smokers versus nonsmokers. A total of 5 studies meeting inclusion criteria were identified. Primary study findings are reviewed and discussed within the context of neurodevelopment and in relation to findings from adult studies. Directions for further research are also discussed.

RESULTS

All identified studies reported increases in fractional anisotropy (FA) among adolescent/young adult smokers in comparison to non-smokers. Increased FA was most frequently reported in regions of the corpus callosum (genu, body and spenium), internal capsule and superior longitudinal fasciculus.

CONCLUSIONS

Findings of increased FA among adolescent/young adult smokers are contrary to those from most adult studies and thus raise the possibility of differential effects of nicotine on white matter across the lifespan. Further research including multiple time points is needed to test this hypothesis. Other areas warranting further research include DTI studies of e-cigarette use and studies incorporating measures of pubertal stage.

Prenatal cocaine exposure, illicit-substance use and stress and craving processes during adolescence

BACKGROUND

Prenatal cocaine exposure (PCE) is associated with increased rates of illicit-substance use during adolescence. In addition, both PCE and illicit-substance use are associated with alterations in cortico-striato-limbic neurocircuitry, development of which is ongoing throughout adolescence. However, the relationship between illicit-substance use, PCE and functional neural responses has not previously been assessed concurrently.

METHODS

Sixty-eight adolescents were recruited from an ongoing longitudinal study of childhood and adolescent development. All participants had been followed since birth. Functional magnetic resonance imaging (fMRI) data were acquired during presentation of personalized stressful, favorite-food and neutral/relaxing imagery scripts and compared between 46 PCE and 22 non-prenatally-drug-exposed (NDE) adolescents with and without lifetime illicit-substance use initiation. Data were analyzed using multi-level ANOVAs (pFWE<.05).

RESULTS

There was a significant three-way interaction between illicit-substance use, PCE status and cue condition on neural responses within primarily cortical brain regions, including regions of the left and right insula. Among PCE versus NDE adolescents, illicit-substance use was associated with decreased subcortical and increased cortical activity during the favorite-food condition, whereas the opposite pattern of activation was observed during the neutral/relaxing condition. Among PCE versus NDE adolescents, illicit-substance use during stress processing was associated with decreased activity in cortical and subcortical regions including amygdala, hippocampus and prefrontal cortex. Neural activity within cortico-striato-limbic regions was significantly negatively associated with subjective ratings of anxiety and craving among illicit-substance users, but not among non-users.

CONCLUSIONS

These findings suggest different neural substrates of experimentation with illicit drugs between adolescents with and without in utero cocaine exposure.

At-Risk/Problematic Shopping and Gambling in Adolescence

Elevated levels of both pathological gambling (PG) and problem shopping (PS) have been reported among adolescents, and each is associated with a range of other negative health/functioning measures. However, relationships between PS and PG, particularly during adolescence, are not well understood. In this study, we explored the relationship between different levels of problem-gambling severity and health/functioning characteristics, gambling-related social experiences, gambling behaviors and motivations among adolescents with and without at-risk/problematic shopping (ARPS). Survey data from Connecticut high school students (n = 2,100) were analyzed using bivariate analyses and logistic regression modeling. Although at-risk/problematic gambling (ARPG) was not increased among adolescents with ARPS, adolescents with ARPG (vs non-gamblers) were more likely to report having experienced a growing tension or anxiety that could only be relieved by shopping and missing other obligations due to shopping. In comparison to the non-ARPS group, a smaller proportion of respondents in the ARPS group reported paid part-time employment, whereas a greater proportion of respondents reported excessive gambling by peers and feeling concerned over the gambling of a close family member. In general, similar associations between problem-gambling severity and measures of health/functioning and gambling-related behaviors and motivations were observed across ARPS and non-ARPS adolescents. However, associations were weaker among ARPS adolescents for several variables: engagement in extracurricular activities, alcohol and caffeine use and gambling for financial reasons. These findings suggest a complex relationship between problem-gambling severity and ARPS. They highlight the importance of considering co-occurring risk behaviors such as ARPS when treating adolescents with at-risk/problem gambling.

Behavioral addictions in addiction medicine: from mechanisms to practical considerations

Recent progress has been made in our understanding of nonsubstance or "behavioral" addictions, although these conditions and their most appropriate classification remain debated and the knowledge basis for understanding the pathophysiology of and treatments for these conditions includes important gaps. Recent developments include the classification of gambling disorder as a "Substance-Related and Addictive Disorder" in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and proposed diagnostic criteria for Internet Gaming Disorder in Section 3 of DSM-5. This chapter reviews current neuroscientific understandings of behavioral addictions and the potential of neurobiological data to assist in the development of improved policy, prevention, and treatment efforts.

Decreased functional connectivity between ventral tegmental area and nucleus accumbens in Internet gaming disorder: evidence from resting state functional magnetic resonance imaging

Background

Internet gaming disorder (IGD) has become an increasing mental health problem worldwide. Decreased resting-state functional connectivity (rsFC) between the ventral tegmental area (VTA) and the nucleus accumbens (NAcc) has been found in substance use and is thought to play an important role in the development of substance addiction. However, rsFC between the VTA and NAcc in a non-substance addiction, such as IGD, has not been assessed previously. The current study aimed to investigate: (1) if individuals with IGD exhibit alterations in VTA-NAcc functional connectivity; and (2) whether VTA-NAcc functional connectivity is associated with subjective Internet craving.

Methods

Thirty-five male participants with IGD and 24 healthy control (HC) individuals participated in resting-state functional magnetic resonance imaging. Regions of interest (left NAcc, right NAcc and VTA) were selected based on the literature and were defined by placing spheres centered on Talairach Daemon coordinates.

Results

In comparison with HCs, individuals with IGD had significantly decreased rsFC between the VTA and right NAcc. Resting-state functional connectivity strength between the VTA and right NAcc was negatively correlated with self-reported subjective craving for the Internet.

Conclusions

These results suggest possible neural functional similarities between individuals with IGD and individuals with substance addictions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12993-015-0082-8) contains supplementary material, which is available to authorized users.

Impaired decision-making under risk is associated with gaming-specific inhibition deficits among college students with Internet gaming disorder

A growing body of evidence indicates that both inhibition and decision-making deficits play essential roles in the development and maintenance of Internet gaming disorder (IGD). Clarifying whether impaired decision-making among individuals with IGD is related to poor inhibition will advance our understanding of IGD and contribute to intervention development. However, the relationship between these two functions remains unclear. In this study, we sought to systemically examine inhibitory processes, decision-making and the relationship between the two among individuals with IGD. Thirty-four individuals with IGD and 32 matched healthy controls (HCs) were recruited. In comparison to HCs, IGD subjects demonstrated inhibition deficits during performance of the gaming-related Go/No-Go task and impaired decision-making under risk. In addition, errors on No-Go trials during the gaming-related Go/No-Go task were positively associated with decision-making impairments under risk but not under ambiguity among IGD subjects. These results suggest individuals with IGD are impaired in some aspects of inhibition and decision-making functions, and that decision-making deficits under risk are linked to poor inhibition specifically related to gaming cues, which has implications for the development of novel intervention.

Hypoactivation of the ventral and dorsal striatum during reward and loss anticipation in antipsychotic and mood stabilizer-naive bipolar disorder

Increased activity within known reward-processing neurocircuitry (eg, ventral striatum, VS) has been reported among medicated individuals with bipolar disorder (BD) I and II. However, such findings are confounded by the potential ameliorative effects of mood-stabilizing and antipsychotic medications on neural activations. This study tests the hypothesis that a pathophysiological locus of alterations in reward processing is present within the striatum in antipsychotic and lithium-naive individuals with BD. Twenty antipsychotic and lithium-naive individuals with BD II or BD not-otherwise specified (NOS) and 20 matched healthy comparison individuals participated in functional magnetic resonance imaging during the performance of a monetary incentive delay task. Between-group comparisons were conducted using small-volume correction focusing on orthogonal a priori regions of interest centered in the VS and dorsal striatum (DS), respectively. During reward anticipation, unmedicated individuals with BD II/NOS had decreased activity within the DS (but not VS). During loss anticipation, on the other hand, decreased activation within both the VS and DS was observed. Across all participants, DS activity (during reward anticipation) was positively associated with putamen volume. This is the first report of decreased dorsal and ventral striatal activity among unmedicated individuals with BD II/NOS. These data contradict a simple 'reward hypersensitivity' model of BD, and add to a growing body of literature suggesting that blunted reward processing may be a vulnerability factor for both mood- and addiction-related disorders.

Decision-making for risky gains and losses among college students with Internet gaming disorder

Individuals with Internet gaming disorder (IGD) tend to exhibit disadvantageous risky decision-making not only in their real life but also in laboratory tasks. Decision-making is a complex multifaceted function and different cognitive processes are involved in decision-making for gains and losses. However, the relationship between impaired decision-making and gain versus loss processing in the context of IGD is poorly understood. The main aim of the present study was to separately evaluate decision-making for risky gains and losses among college students with IGD using the Cups task. Additionally, we further examined the effects of outcome magnitude and probability level on decision-making related to risky gains and losses respectively. Sixty college students with IGD and 42 matched healthy controls (HCs) participated. Results indicated that IGD subjects exhibited generally greater risk taking tendencies than HCs. In comparison to HCs, IGD subjects made more disadvantageous risky choices in the loss domain (but not in the gain domain). Follow-up analyses indicated that the impairment was associated to insensitivity to changes in outcome magnitude and probability level for risky losses among IGD subjects. In addition, higher Internet addiction severity scores were associated with percentage of disadvantageous risky options in the loss domain. These findings emphasize the effect of insensitivity to losses on disadvantageous decisions under risk in the context of IGD, which has implications for future intervention studies.

Increased temporo-insular engagement in unmedicated bipolar II disorder: an exploratory resting state study using independent component analysis

OBJECTIVES

Despite numerous structural and functional magnetic resonance imaging studies, the neurobiology of bipolar disorder (BD) is still incompletely understood. Resting-state functional magnetic resonance imaging (rsFMRI) allows for the study of intrinsic functional connections between brain areas, which may reflect the pathophysiology of BD. Most previous rsFMRI studies conducted in BD have included a majority of medicated patients, making simple interpretation with respect to pathophysiology difficult.

METHODS

Participants were 15 antipsychotic agent- and mood-stabilizer-naïve young adults with bipolar II disorder (BD-II), and 20 healthy controls group-matched for gender, age, and cognitive ability. Independent component analysis (ICA) was used to identify eight commonly studied resting-state networks (RSNs). Between-group comparisons were conducted using dual regression and corrected for family-wise error (FWE) across space and the number of components (pFWE < 0.05).

RESULTS

In comparison to controls, participants with BD-II had increased coherence across several brain regions, including the bilateral insula and putamen, across a temporo-insular network. No between-group differences in engagement of the default mode network were found.

CONCLUSIONS

This was the first ICA-based rsFMRI study conducted among unmedicated individuals with BD. Given the young age (mean = 23 years) and antipsychotic agent- and mood-stabilizer-naïve status of our participants with BD-II, temporo-insular functional connectivity is a candidate vulnerability marker for BD. Further work is needed to relate resting-state differences to detailed understanding of pathophysiology.

Pretreatment measures of brain structure and reward-processing brain function in cannabis dependence: an exploratory study of relationships with abstinence during behavioral treatment

BACKGROUND

Cannabis is widely abused, and efficacies of therapeutics for cannabis dependence remain suboptimal. Magnetic resonance imaging (MRI) may aid in the identification of biological markers for successful treatment outcomes (i.e., abstinence).

METHODS

Twenty men with cannabis dependence and twenty non-substance-using healthy comparison (HC) men underwent MRI scanning. Cannabis-dependent individuals then participated in a 12-week randomized clinical trial of behavioral treatments (contingency management (CM), cognitive behavioral therapy (CBT) or both). Pretreatment functional and structural data were compared between the cannabis-dependent and HC participants. In addition, individuals with cannabis dependence were subdivided based on the successful achievement of 21 days of consecutive abstinence during treatment to assess whether abstinent versus non-abstinent cannabis-dependent participants displayed different pretreatment functional and structural characteristics when compared to HC participants.

RESULTS

In comparison to HC participants, cannabis-dependent participants demonstrated greater ventral striatal activation during the receipt of losing outcomes and smaller putamenal volumes. Cannabis-dependent participants who did not subsequently achieve 21 days of consecutive abstinence had increased activity within the striatum during the receipt of losing outcomes, relative to HC participants. Cannabis-dependent participants who did not achieve 21 days of abstinence had decreased bilateral putamen volumes prior to treatment, relative to HC participants.

CONCLUSIONS

Individual differences in pretreatment striatal function and structure may relate to individual differences in treatment responses for cannabis dependence. While mechanisms underlying these associations require further exploration, the striatum might mediate treatment responses via its role in associative reward-learning (e.g., through skills training in CBT or reinforcement of abstinence in CM).

Treatment of Gambling Disorders

Preclinical and clinical research implicate several neurotransmitter systems in the pathophysiology of gambling disorder (GD). In particular, neurobiological research suggests alterations in serotonergic, dopaminergic, glutamatergic and opioidergic functioning. The relative efficacy of medications targeting these systems remains a topic of ongoing research, and there is currently no Food and Drug Administration (FDA) approved medication with an indication for GD. Considering co-occurring disorders may be particularly important when devising a treatment plan for GD: extant data suggest that the opioid antagonist naltrexone may by the most effective form of current pharmacotherapy for GD, particularly for individuals with a co-occurring substance-use disorder (SUD) or with a family history of alcoholism. In contrast, lithium or other mood stabilizers may be most effective for GD for patients presenting with a co-occurring bipolar-spectrum disorder (BSD). Further, serotonin reuptake inhibitors (SRIs) may be efficacious in reducing GD symptoms for individuals also presenting with a (non-BSD) mood or anxiety disorder. Finally, elevated rates of GD (and other Impulse Control Disorders; ICDs) have been noted among individuals with Parkinson's Disease (PD), and clinicians should assess for vulnerability to GD when considering treatment options for PD. Reducing levodopa or dopamine agonist (DA) dosages may partially reduce GD symptoms among patients with co-occurring PD. For GD patients not willing to consider drug treatment, n-acetyl cysteine or behavioral therapies may be effective. Ongoing research into the effectiveness of combined behavioral and pharmacotherapies is being conducted; thus combined treatments should also be considered.

Cortical glutathione levels in young people with bipolar disorder: a pilot study using magnetic resonance spectroscopy

RATIONALE

Glutathione (GSH) is a key scavenger for cellular free radicals, and patients with bipolar disorder may have lowered GSH levels in plasma and in post-mortem brain tissue.

OBJECTIVES

The objective of the current study was to use magnetic resonance spectroscopy (MRS) to measure cortical GSH levels in young people with bipolar disorder to determine if lowered GSH might be a useful biomarker of vulnerability to the illness.

METHODS

We studied 13 patients with DSM-IV bipolar disorder and 11 healthy age-matched controls using proton MRS in conjunction with the SPECIAL acquisition technique. Voxels were placed in prefrontal and occipital cortex. All patients were clinically euthymic at the time of study and unmedicated. GSH and other relevant neurometabolites were measured relative to creatinine.

RESULTS

There was no difference in GSH levels between bipolar participants and controls in either prefrontal or occipital cortex. Similarly, participants showed no difference from controls in other measured cortical metabolites including γ-aminobutyric acid, glutamate and N-acetylaspartate.

CONCLUSIONS

This pilot study suggests that levels of cortical GSH are unlikely to be a useful trait biomarker of bipolar disorder in young people with a history of relatively mild mood instability at an early stage of illness. Lowered GSH levels may be relevant to bipolar pathophysiology in more severely ill patients, particular those with significant current mood disturbance.

White matter alterations in antipsychotic- and mood stabilizer-naïve individuals with bipolar II/NOS disorder

Structural magnetic resonance imaging (MRI) studies using voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) have been inconsistent in demonstrating impairments in gray matter (GM) and white matter (WM) structures in bipolar disorder (BD). This may be a consequence of significant confounding effects of medication, illness history and selection of controls in existing studies. Study of bipolar II or not-otherwise-specified (BD II/NOS) disorder provides a solution to these confounds and a bridge to unipolar cases across the affective spectrum. Thirty-eight euthymic, antipsychotic- and mood stabilizer-naïve young adults (mean age = 20.9 years) with BD II/NOS and 37 age-, cognitive ability- and gender-matched healthy controls (HCs) underwent MRI. Voxel-wise and regional gray matter volume comparisons were conducted using voxel-based morphometry (VBM). Tract-based spatial statistics (TBSS) were used to assess whole-brain WM, as indexed using fractional anisotropy (FA), mean diffusivity (MD), parallel and perpendicular diffusion values. No between-group differences were observed for whole-brain VBM comparisons. By contrast, in comparison to HCs, participants with BD II/NOS had significant widespread reductions in FA and increased MD and perpendicular diffusion values in virtually all the major cortical white matter tracts. These data suggest pathophysiological involvement of WM microstructures - but not GM macrostructures - in high functioning BD II/NOS patients at an early age and before significant clinical adversity has been recorded. We propose that white matter development is a valid candidate target for understanding genetic and environmental antecedents to bipolar disorder and mood disorder more generally.

Reduced genual corpus callosal white matter integrity in pathological gambling and its relationship to alcohol abuse or dependence

OBJECTIVE

Magnetic resonance imaging (MRI) studies have demonstrated functional prefrontal cortical (PFC) abnormalities in pathological gambling (PG) and other psychiatric disorders characterized by impaired impulse control; e.g., cocaine dependence and bipolar disorder. These abnormalities are accompanied by impairments in white matter microstructures in the anterior (genual) corpus callosum (CC) in cocaine dependence and bipolar disorder. Prior studies have not examined white matter integrity in PG. We predicted impairments in genual CC white matter in PG.

METHODS

Nineteen participants with PG and 19 matched control participants underwent diffusion tensor imaging (DTI) to compare white matter integrity in the CC, as assessed using fractional anisotropy (FA).

RESULTS

In PG subjects as compared to control subjects, reduced FA values in the left and right genu of the CC were observed. Multiple regression analyses confirmed that PG status - in addition to age and past alcohol abuse/dependence (AA/AD) - was a significant predictor of genual FA values. Among PG participants, left and right genu FA values were negatively correlated with scores on the Behavioral Activation System Fun-Seeking (BAS-FS) subscale. Limitations. Limitations include a reliance on self-report measures of impulsivity and related constructs and a relatively small sample of PG subjects with past AA/AD.

CONCLUSION

Findings of decreased FA values in the genu of the CC in PG subjects suggest that, like with other disorders of behavioral dyscontrol, white matter microstructural abnormalities contribute to the pathophysiology of PG. These differences appear particularly relevant to individuals with remitted AA/AD, highlighting the importance of considering co-occurring substance use disorders when investigating PG.

An exploratory study of clinical measures associated with subsyndromal pathological gambling in patients with binge eating disorder

Both binge eating disorder (BED) and pathological gambling (PG) are characterized by impairments in impulse control. Subsyndromal levels of PG have been associated with measures of adverse health. The nature and significance of PG features in individuals with BED is unknown. Ninety-four patients with BED (28 men and 66 women) were classified by gambling group based on inclusionary criteria for Diagnostic and Statistical Manual-IV (DSM-IV) PG and compared on a range of behavioral, psychological and eating disorder (ED) psychopathology variables. One individual (1.1% of the sample) met criteria for PG, although 18.7% of patients with BED displayed one or more DSM-IV criteria for PG, hereafter referred to as problem gambling features. Men were more likely than women to have problem gambling features. BED patients with problem gambling features were distinguished by lower self-esteem and greater substance problem use. After controlling for gender, findings of reduced self-esteem and increased substance problem use among patients with problem gambling features remained significant. In patients with BED, problem gambling features are associated with a number of heightened clinical problems.

Health/functioning characteristics, gambling behaviors, and gambling-related motivations in adolescents stratified by gambling problem severity: findings from a high school survey

In adults, different levels of gambling problem severity are differentially associated with measures of health and general functioning, gambling behaviors, and gambling-related motivations. Here we present data from a survey of 2,484 Connecticut high school students, and investigate the data stratifying by gambling problem severity based on DSM-IV criteria for pathological gambling. Problem/pathological gambling was associated with a range of negative functions; for example, poor academic performance, substance use, dysphoria/depression, and aggression. These findings suggest a need for improved interventions related to adolescent gambling and a need for additional research into the relationship (eg, mediating factors) between gambling and risk and protective behaviors.

Risk/reward decision-making in schizophrenia: a preliminary examination of the influence of tobacco smoking and relationship to Wisconsin Card Sorting Task performance

BACKGROUND

Individuals with schizophrenia show deficits in cognitive functioning, as evidenced by deficits on neurocognitive tasks such as the Wisconsin Card Sorting Task (WCST). Studies of risk/reward decision-making in individuals with schizophrenia have yielded mixed results, and few studies have examined systematically the relationship between these domains and their relationship with clinical factors.

METHOD

Thirty-two smokers with schizophrenia, ten non-smokers with schizophrenia, nine non-psychiatric non-smokers and ten non-psychiatric smokers were administered computerized versions of the Iowa Gambling Task (IGT) and the WCST. Smokers were allowed to smoke adlibitum during designated breaks in order to prevent deprivation.

RESULTS

Subjects with schizophrenia performed significantly worse than non-psychiatric controls on both the IGT and the WCST, and performance on these tasks was significantly correlated across subject groups. Among women with schizophrenia, smokers performed significantly better than non-smokers on the IGT.

CONCLUSIONS

Individuals with schizophrenia perform worse than controls on the IGT, suggesting impairments in risk/reward decision-making. Correlations between IGT and WCST performance suggest a shared element underlying task performance, such as a deficit in set-shifting or perseverance. Further research is needed to establish the relationship between cigarette smoking and IGT performance in schizophrenia.

[The tracing of brain tissue and 3-D imaging display CT image application: 3-D recursive tracing]

The size and the shape of brain tissue offer lots of information for clinical diagnosis and treatment. The commercial imaging systems, such as x-ray computer tomography (CT) and magnetic resonant image (MRI), always display only two dimensional (2-D) image, which makes quantitative diagnosis of the variation of brain tissue very difficult. Furthermore, some tissue may be connected through little vessels, which is also difficult to identify using discrete 2-D image. In this study, we processed CT image data using an general purpose IBM personal computer. A new three dimensional (3-D) recursive tracing algorithm was proposed. This new algorithm can automatically extract the image of brain tissue in each 2-D image. The information obtained was therefore used to reconstruct 3-D image. This system allows user to observe 3-D size and shape of brain tissue from arbitrary view. Such 3-D image can also be used to calculate the volume of tissue. Using overlay projecting method, it can display skin, bone, brain tissue and gray material at the same time. Such display method accurately shows the relative position of each tissue and offer physicians important information for diagnosis and treatment.