Catherine M. Brignell

Attentional and approach biases for pictorial food cues. Influence of external eating

Individual differences in sensitivity of neural reward systems to external appetitive cues may determine normal and pathological eating behaviour. In the current study we investigated the relationship between cognitive biases for food cues and the trait predisposition of external eating (eating in response to external food cues). Biases in attention, approach and subjective evaluation of food cues were assessed on pictorial visual probe, stimulus response compatibility (SRC) and pleasantness rating tasks, respectively, in a sample of non-clinical participants. High-external eating was associated with a greater attentional bias for food cues, as well as with a bias to evaluate them more positively. The relationship between external eating and the approach bias for food cues was less clear (i.e., high-external eating was not significantly associated with greater approach bias after controlling the effect of emotional eating). Results support the view that there is individual variation in trait sensitivity of the reward system to external food cues. Implications for models of cognitive mechanisms that underlie normal and pathological motivational states are discussed.

Negative mood increases selective attention to food cues and subjective appetite.

Following negative reinforcement and affect-regulation models of dysfunctional appetitive motivation, this study examined the effect of negative mood on objective and subjective cognitive indices of motivation for food; i.e., attentional bias for food cues and self-reported hunger/urge to eat, respectively. The study extended previous research on the effect of mood on food motivation by using (i) an experimental mood manipulation, (ii) an established index of attentional bias from the visual-probe task and (iii) pictorial food cues, which have greater ecological validity than word stimuli. Young female adults (n=80) were randomly allocated to a neutral or negative mood induction procedure. Attentional biases were assessed at two cue exposure durations (500 and 2000ms). Results showed that negative mood increased both attentional bias for food cues and subjective appetite. Attentional bias and subjective appetite were positively inter-correlated, suggesting a common mechanism, i.e. activation of the food-reward system. Attentional bias was also associated with trait eating style, such as external and restrained eating. Thus, current mood and trait eating style each influenced motivation for food (as reflected by subjective appetite and attentional bias). Findings relate to models of cognitive mechanisms underlying normal and dysfunctional appetitive motivation and eating behaviour.

Pharmacological manipulations of arousal and memory for emotional material: effects of a single dose of methylphenidate or lorazepam

Benzodiazepines produce robust impairments of memory alongside global decreases in physiological and subjective arousal. Recently one benzodiazepine (triazolam) has been found to disproportionately impair memory for emotionally arousing material (Buchanan et al., 2003). The extent to which this effect may be mediated by the drugs sedative action is unclear. The present study aimed to assess how pharmacologically decreasing physiological arousal with a benzodiazepine and increasing arousal with a stimulant impact on memory for emotional material. A double-blind placebo controlled trial with 48 volunteers was used to investigate the effects of methylphenidate (40 mg) and Lorazepam (1.5 mg) on incidental memory for emotional material in Cahill and McGaughs (1995) slide-story task. The slide-story was presented to participants administered either active drug or placebo and retrieval was assessed one week later. Methylphenidate produced stimulant effects and Lorazepam produced sedative effects. Significantly enhanced memory for emotional material was observed in participants given placebo, but not in those given either methylphenidate or Lorazepam. Despite producing opposite effects upon arousal, both methylphenidate and Lorazepam lessen the impact of emotionally arousing material on memory. The effects of Lorazepam add to a growing literature that benzodiazepines may exert their clinical, anxiolytic effects in part via altering emotionaL cognitive function.

The association between the use of social network sites, sleep quality and cognitive function during the day

Previous studies have suggested that excessive use of the internet can affect the daily cognitive functioning of users. Furthermore, it has been argued that excessive users of the internet could demonstrate addiction behaviour patterns. Social network sites (SNS) are currently one of the most popular applications of internet use and have almost one billion active users. Studies which examined the dependence on the use of internet have found significant association with sleep deprivation. This study examined associations between questionnaire measures of SNS use, sleep quality and everyday cognitive failures in 324 users of SNS. The sample ranged from 18 to 58 years old and was drawn from 29.6% males and 70.4% females from diverse countries and educational backgrounds. Additionally, behaviours indicating potential dependence on SNS were examined with a new-developed questionnaire. Results indicated that increased dependence on SNS was correlated with decreased sleep quality and with increased everyday cognitive failures. The correlation of SNS use with cognitive failures was mediated by sleep quality. Finally, the final nine items of the new developed questionnaire indicated Withdrawal and Compulsion as two distinct but correlated aspects of possible dependence on SNS. We examined associations between social media use, sleep and cognitive function.Social network sites (SNS) dependence was assessed with a 9-item questionnaire.Withdrawal and Compulsion were the components of our questionnaire.SNS dependence was correlated with decreased sleep quality and cognitive function.Sleep quality mediated the effect of the dependence on SNS on cognitive failures.

Persistent Nigrostriatal Dopaminergic Abnormalities in Ex-Users of MDMA (‘Ecstasy'): An 18F-Dopa PET Study

Ecstasy (±3,4-methylenedioxymethamphetamine, MDMA) is a popular recreational drug with known serotonergic neurotoxicity. Its long-term effects on dopaminergic function are less certain. Studying the long-term effects of ecstasy is often confounded by concomitant polydrug use and the short duration of abstinence. We used 18F-dopa positron emission tomography (PET) to investigate the long-term effects of ecstasy on nigrostriatal dopaminergic function in a group of male ex-recreational users of ecstasy who had been abstinent for a mean of 3.22 years. We studied 14 ex-ecstasy users (EEs), 14 polydrug-using controls (PCs) (matched to the ex-users for other recreational drug use), and 12 drug-naive controls (DCs). Each participant underwent one 18F-dopa PET, cognitive assessments, and hair and urinary analyses to corroborate drug-use history. The putamen 18F-dopa uptake of EEs was 9% higher than that of DCs (p=0.021). The putamen uptake rate of PCs fell between the other two groups, suggesting that the hyperdopaminergic state in EEs may be due to the combined effects of ecstasy and polydrug use. There was no relationship between the amount of ecstasy used and striatal 18F-dopa uptake. Increased putaminal 18F-dopa uptake in EEs after an abstinence of >3 years (mean) suggests that the effects are long lasting. Our findings suggest potential long-term effects of ecstasy use, in conjunction with other recreational drugs, on nigrostriatal dopaminergic functions. Further longitudinal studies are required to elucidate the significance of these findings as they may have important public health implications.