Melanie J. White

Choice impulsivity: Definitions, measurement issues, and clinical implications

Impulsivity critically relates to many psychiatric disorders. Given the multifaceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, represents one important type of impulsivity. The International Society for Research on Impulsivity (InSRI) convened to discuss the definition and assessment of CI and provide recommendations regarding measurement across species. Commonly used preclinical and clinical CI behavioral tasks are described, and considerations for each task are provided to guide CI task selection. Differences in assessment of CI (self-report, behavioral) and calculating CI indices (e.g., area-under-the-curve, indifference point, and steepness of discounting curve) are discussed along with properties of specific behavioral tasks used in preclinical and clinical settings. The InSRI group recommends inclusion of measures of CI in human studies examining impulsivity. Animal studies examining impulsivity should also include assessments of CI and these measures should be harmonized in accordance with human studies of the disorders being modeled in the preclinical investigations. The choice of specific CI measures to be included should be based on the goals of the study and existing preclinical and clinical literature using established CI measures.

Interaction Between DRD2 C957T Polymorphism and An Acute Psychosocial Stressor on Reward-Related Behavioral Impulsivity

The dopamine D2 receptor (DRD2) C957T polymorphism CC genotype is associated with decreased striatal binding of DRD2 and executive function and working memory impairments in healthy adults. We investigated the relationships between C957T and acute stress with behavioral phenotypes of impulsivity in 72 young adults randomly allocated to either an acute psychosocial stress or relaxation induction condition. Homozygotes for 957C showed increased reward responsiveness after stress induction. They were also quicker when making immediate choices on the delay discounting task when stressed, compared with homozygotes who were not stressed. No effects were found for response inhibition, a dimension of impulsivity not related to extrinsic rewards. These data suggest that C957T is associated with a reward-related impulsivity endophenotype in response to acute psychosocial stress. Future studies should examine whether the greater sensitivity of 957C homozygotes to the effects of stress is mediated through dopamine release.

Cigarette smoking in young adults: The influence of the HTR2A T102C polymorphism and punishment sensitivity

BACKGROUND The C allele of a common polymorphism of the serotonin 2A receptor (HTR2A) gene, T102C, results in reduced synthesis of 5-HT2A receptors and has been associated with current smoking status in adults. The -1438A/G polymorphism, located in the regulatory region of this gene, is in linkage disequilibrium with T102C, and the A allele is associated with increased promoter activity and with smoking in adult males. We investigated the contributions of the HTR2A gene, chronic psychological stress, and impulsivity to the prediction of cigarette smoking status and dependence in young adults. METHODS T102C and -1438A/G genotyping was conducted on 132 healthy Caucasian young adults (47 smokers) who completed self-report measures of chronic stress, depressive symptoms, impulsive personality and cigarette use. RESULTS A logistic regression analysis of current cigarette smoker user status, after adjusting for gender, depressive symptom severity and chronic stress, indicated that the T102C TT genotype relative to the CC genotype (OR=7.53), and lower punishment sensitivity (OR=0.91) were each significant predictive risk factors. However, for number of cigarettes smoked, only lower punishment sensitivity was a significant predictor (OR=0.81). CONCLUSIONS These data indicate the importance of the T102C polymorphism to tobacco use but not number of cigarettes smoked for Caucasian young adults. Future studies should examine whether this is explained by effects of nicotine on the serotonin system. Lower punishment sensitivity increased risk of both smoking and of greater consumption, perhaps via a reduced sensitivity to cigarette health warnings and negative physiological effects.

Psychological predictors of opportunistic snacking in the absence of hunger.

Increased frequency of eating in the absence of homeostatic need, notably through snacking, is an important contributor to overconsumption and may be facilitated by increased availability of palatable food in the obesogenic environment. Opportunistic initiation of snacking is likely to be subject to individual differences, although these are infrequently studied in laboratory-based research paradigms. This study examined psychological factors associated with opportunistic initiation of snacking, and predictors of intake in the absence of homeostatic need. Fifty adults (mean age 34.5years, mean BMI 23.9kg/m(2), 56% female) participated in a snack taste test in which they ate a chocolate snack to satiation, after which they were offered an unanticipated opportunity to initiate a second eating episode. Trait and behavioural measures of self control, sensitivity to reward, dietary restraint and disinhibited eating were taken. Results showed that, contrary to expectations, those who initiated snacking were better at inhibitory control compared with those who did not initiate. However, amongst participants who initiated snacking, intake (kcal) was predicted by higher food reward sensitivity, impulsivity and BMI. These findings suggest that snacking initiation in the absence of hunger is an important contributor to overconsumption. Consideration of the individual differences promoting initiation of eating may aid in reducing elevated eating frequency in at-risk individuals.

The use of neurocognitive methods in assessing health communication messages: A systematic review.

We review 20 studies that examined persuasive processing and outcomes of health messages using neurocognitive measures. The results suggest that cognitive processes and neural activity in regions thought to reflect self-related processing may be more prominent in the persuasive process of self-relevant messages. Furthermore, activity in the medial prefrontal cortex, the superior temporal gyrus and the middle frontal gyrus were identified as predictors of message effectiveness, with the medial prefrontal cortex accounting for additional variance in behaviour change beyond that accounted for by self-report measures. Incorporating neurocognitive measures may provide a more comprehensive understanding of the processing and outcomes of health messages.

A Systematic Review and Meta-analysis of Executive Function Performance in Type 1 Diabetes Mellitus

Objective The aims of the study were to examine the current evidence for executive function (EF) performance differences between groups with type 1 diabetes mellitus (T1DM) and nondiabetic control groups during adolescence and early adulthood and to explore the relationships between EF and diabetes-related risk factors. Methods A systematic review of the literature examining EF performance in groups with T1DM was conducted according to the PRISMA guidelines. Electronic database searches for published and unpublished literature yielded a final set of 26 articles after application of inclusion and exclusion criteria. A meta-analysis was conducted on a subset of these articles (n = 17) comparing EF performance in T1DM and control groups, across a total sample size of 1619. Results Sixteen of 26 studies found significantly lower EF on at least one task in groups with T1DM. Meta-analyses of the performance difference between T1DM groups and control groups without diabetes showed that inhibition (g = −0.28, p < .001), working memory (g = −0.34, p < .001), set-shifting (g = −0.31, p = .012), and overall EF performance across these domains (g = −0.42, p < .001) were all significantly lower in groups with T1DM. Performance on specific EF domains also seemed to be differentially associated with early age of diabetes onset, chronic hyperglycemia and its complications, and severe hypoglycemia. Conclusions T1DM and its associated risk factors are related to subtle impairments across the inhibition, working memory, and set-shifting domains of EF. Lower EF may be a key factor contributing to behavioral and clinical problems experienced by individuals with T1DM.

The effects of priming in a cued dot-probe task on appearance-related attentional biases in women.

The dot-probe task (DPT) is a reaction time measure of attentional bias. Research using this task has found inconsistent patterns of appearance-related attentional biases in women. This study examined the effects of a novel priming variation of the DPT, which incorporated additional cues into each trial of the task, on measurement of such biases. The study also examined associations between these biases and body image, a component of eating disorder symptomatology. A convenience sample of women from the general community (N = 103) completed body image measures online and attended a laboratory session to complete one of four DPTs: (1) an appearance-cued DPT containing images of thin-ideal models between each trial; (2) neutral-cued DPT containing images of forests; (3) time-delayed DPT controlling for time in place of an image; or (4) typical DPT containing only word stimuli. Women who completed the appearance-cued DPT demonstrated a stronger attentional bias for positive, but not negative, appearance words than women who completed the other DPT versions. Furthermore, for the appearance-cued and time-delayed DPTs, this bias correlated with poorer body image across several indicators (appearance evaluation, body dissatisfaction, self-evaluative salience of appearance, and state body satisfaction). Although it was unexpected that no attentional bias for negative-appearance words was found, the attentional bias for positive-appearance words may suggest that effects were driven by the ego-threat of positive-appearance words. Further research is warranted to determine whether such biases contribute to and maintain body image disturbance and disordered eating.

Pleiotropic effects of Chr15q25 nicotinic gene cluster and the relationship between smoking, cognition and ADHD.

Polymorphisms in the CHRNA5-CHRNA3-CHRNB4 gene cluster (Chr15q25) have been robustly associated with nicotine dependence, including genome-wide studies, as well as with cognitive and neuropsychological measures. In addition, cognitive processes can be influenced by nicotine use through nicotinic acetylcholine receptors (nAChRs). Here, we evaluated the effect of polymorphisms in CHRNA5-CHRNA3-CHRNB4 gene cluster and their interaction with tobacco smoking status on cognition in patients with Attention Deficit/Hyperactivity Disorder (ADHD). Eight SNPs from the CHRNA5-CHRNA3-CHRNB4 gene cluster were evaluated on a clinical sample of 403 adults with ADHD. Cognitive performance was assessed using the Wechsler Adult Intelligence Scale-Revised (WAIS-R). Analyses of covariance were used to assess the influence of single markers and their interaction with smoking status in the Vocabulary and Block Design subtests of WAIS-R. Correction for multiple comparisons was applied. Lifetime smoking was associated to Vocabulary subtest. The TT genotypes of CHRNA5 SNPs rs588765 and rs514743 showed a trend towards association with, respectively, higher and lower scores on the Vocabulary subtest. There was a significant interaction between intergenic SNP rs8023462 and smoking on Vocabulary scores. Our results are consistent with an influence of variants in the CHRNA5-CHRNA3-CHRNB4 gene cluster on cognitive measures. The overall scenario suggests a pleiotropic role of Chr15q25 nicotinic gene cluster with complex influences in ADHD, tobacco smoking and cognitive performance, characteristics that can be partially interdependent and may share underlying genetic factors.

Posttraumatic Growth in Family Members Living With a Relative Diagnosed With Schizophrenia

Family members living with a relative diagnosed with schizophrenia have reported challenges and traumatic stressors, as well as perceived benefits and personal growth. This study explored factors associated with posttraumatic growth (PTG) within such families. Personality, stress, coping, social support, and PTG were assessed in 110 family members. Results revealed that a multiplicative mediational path model with social support and emotional or instrumental coping strategies as multi-mediators had a significant indirect effect on the relationship between extraversion and PTG. Clinically relevant concepts that map onto the multi-mediator model are discussed, and these findings are translated into clinical practice to facilitate naturally occurring PTG processes.

The Impact of Rewards and Trait Reward Responsiveness on Player Motivation

Despite rewards being seemingly ubiquitous in video games, there has been limited research into their impact on the player experience. Informed by extant literature, we built a casual video game to test the impact of reward types, both individually (i.e. rewards of: access, facility, sustenance, glory, praise) and by variety of rewards (i.e. no rewards, individual rewards, all rewards). No evidence was found for differing reward types impacting the player experience differently. However, evidence was found for a greater variety of rewards having a positive impact on interest and enjoyment. Regardless of the impact of variety of rewards, the individual characteristic of reward responsiveness was found to be predict sense of presence and interest and enjoyment. This paper makes contributions to the application of reward types, general understanding of the impact of rewards on the player experience, and discusses the importance of trait reward responsiveness in player experience evaluation.