Subcutaneous pulsatile glucocorticoid replacement therapy.

The glucocorticoid hormone cortisol is released in pulses resulting in a complex and dynamic ultradian rhythm of plasma cortisol that underlies the classical circadian rhythm. These oscillating levels are also seen at the level of tissues such as the brain and trigger pulses of gene activation and downstream signalling. Different patterns of glucocorticoid presentation (constant vs pulsatile) result not only in different patterns of gene regulation but also in different neuroendocrine and behavioural responses. Current 'optimal' glucocorticoid replacement therapy results in smooth hormone blood levels and does not replicate physiological pulsatile cortisol secretion. Validation of a novel portable pulsatile continuous subcutaneous delivery system in healthy volunteers under dexamethasone and metyrapone suppression. Pulsatile subcutaneous hydrocortisone more closely replicates physiological circadian and ultradian rhythmicity.

Effects of 7.5% carbon dioxide inhalation on anxiety and mood in cigarette smokers.

Cigarette smoking is associated with elevated risk of anxiety and mood disorder. Using the 7.5% carbon dioxide (CO2) inhalation model of anxiety induction, we examined the effects of smoking status and abstinence from smoking on anxiety responses. Physiological and subjective responses to CO2 and medical air were compared in smokers and non-smokers (Experiment One) and in overnight abstinent and non-abstinent smokers (Experiment Two). CO2 induced greater increases in blood pressure in non-smokers compared with smokers (ps < 0.043), and greater increases in anxiety (p = 0.005) and negative affect (p = 0.054) in non-abstinent compared with abstinent smokers. CO2 increased physiological and subjective indices of anxiety. There were differences across smoking groups indicating that the CO2 inhalation model is a useful tool for examining the relationship between smoking and anxiety. The findings suggested that both acute smoking and acute abstinence may protect against anxious responding. Further investigation is needed in long-term heavy smokers.

Effects of alcohol on disinhibition towards alcohol-related cues.

BACKGROUND: We investigated (1) the effects of acute alcohol on inhibition of alcohol-related versus neutral cues, (2) the effects of drinking status on inhibition of alcohol-related versus neutral cues, and (3) the similarity of any effects of alcohol or drinking status across two different cue types (lexical versus pictorial). METHODS: Participants received 0.0 g/kg, 0.4 g/kg or 0.6g/kg of alcohol in a between-subjects design. Healthy, heavy and light social alcohol users (n=96) completed both lexical and pictorial cue versions of an alcohol-shifting task. Participants were instructed to respond to target stimuli by pressing the spacebar, but to ignore distracter stimuli. Errors towards distracter stimuli were analysed using a series of mixed-model ANOVAs, with between-subjects factors of challenge and drinking status and within-subjects factors of distracter type (alcohol, neutral) and block (shift, non-shift). RESULTS: Lexical commission error data indicated a main effect of distracter (F [1,90]=43.25, p<0.001, η(2)=0.33), which was qualified by a marginal interaction with challenge condition (F [2,90]=2.77, p=0.068, η(2)=0.06). Following an acute high dose of alcohol participants made more errors towards alcohol distracters. Pictorial commission error data indicated a significant main effect of distracter (F [1,90]=67.40, p<0.001, η(2)=0.43), such that all participants made more errors towards neutral image distracters versus alcohol distracter images. CONCLUSIONS: Our results reveal acute alcohol's impairment of inhibitory control may be enhanced when a response towards alcohol-related lexical stimuli is required to be withheld.

Methodological considerations in cognitive bias research: the next steps.

Field and Christiansen (2012) comment on the importance of establishing and understanding the internal reliability of measures of substance-related cognitive bias, and suggest potential reasons for the poor reliability of some task variants. We agree that the impact of using stimuli personalized to the participant on the reliability of cognitive bias tasks is worthy of systematic investigation. However, some tasks may still be inherently less reliable than others. Ultimately, this debate should be framed within the wider debate on the validity of laboratory models and methods used to assess real-world phenomena.

Internal reliability of measures of substance-related cognitive bias.

AIMS: There is growing interest in cognitive biases related to substance use, but evidence from the anxiety literature suggests that tasks commonly used to assess these may suffer from low internal reliability. We examined the internal reliability of the visual probe and modified Stroop tasks. DESIGN: Secondary analysis of visual probe and modified Stroop task data collected across seven independent studies. SETTING: Human laboratory study. PARTICIPANTS: Healthy volunteers (n=408 across seven independent studies) recruited from the general population on the basis of alcohol or tobacco use. MEASUREMENTS: Visual probe and modified Stroop task measures of substance-related cognitive bias. FINDINGS: Measures of cognitive bias for substance-related cues, as assayed by the visual probe and the modified Stroop tasks, may not be reliable. In particular, the visual probe task showed poor internal reliability, as did unblocked versions of the modified Stroop task. CONCLUSIONS: The modified Stroop task is preferable to the visual probe task as a measure of substance-related cognitive bias, on the basis of its psychometric properties. Studies using cognitive bias tasks should not assume they are reliable, and should routinely report reliability estimates where possible.

Effects of caffeine on alcohol-related changes in behavioural control and perceived intoxication in light caffeine consumers.

RATIONALE: Caffeinated alcoholic beverages have been associated with increased risk of alcohol-related harms. However, few studies have examined these combined effects on behavioural control, which is believed to underlie many of the negative effects of alcohol consumption. In addition, studies have often omitted subjective measures, and none have directly assessed the role of caffeine consumer history. OBJECTIVES: To examine the combined effects of alcohol and caffeine on measures of behavioural control and perceived intoxication in abstinent, light caffeine consumers. METHODS: Participants (n = 28; 50% male) attended four sessions at which they consumed one of the following beverages in a randomised order: placebo, alcohol alone (0.6 g/kg), caffeine alone (2.0 mg/kg), and alcohol/caffeine. They completed measures of mood, intoxication, anxiety and alcohol craving before and after a task battery comprising measures of behavioural control and reaction time performance. RESULTS: Caffeine attenuated alcohol-related performance deficits on stop-signal accuracy, had no effect on go-no-go performance deficits, and worsened accuracy on the Stroop task. Caffeine did not influence absolute changes in perceived intoxication but there was suggestion that caffeine may have changed the nature of intoxication with increases in stimulation. CONCLUSIONS: Caffeine appears to have mixed effects on alcohol intoxication that are task-dependent. We found increased stimulation in the alcohol/caffeine condition, supporting the contention that caffeinated alcoholic beverages enable an individual to drink for longer. Future research should model real world drinking behaviour by examining how these effects change across multiple drink administrations.

Effects of acute alcohol consumption on alcohol-related cognitive biases in light and heavy drinkers are task-dependent.

We investigated (1) the effects of alcohol on cognitive biases for alcohol-related cues, (2) the effects of drinking status on alcohol-related cognitive biases and (3) the similarity of any effects of alcohol across two measures of alcohol cognitive bias. Healthy, heavy and light social alcohol users (n = 72) were examined in a single-blind placebo-controlled design. Participants received 0.00 g/kg, 0.13 g/kg or 0.40 g/kg of alcohol in a between-subjects design and then completed both a modified Stroop task and a visual probe task. Modified Stroop data indicated a main effect of cue type, which was qualified by drinking status, with heavier drinkers slower to respond to alcohol-related cues. Visual probe data, in contrast, indicated a significant interaction effect between validity (valid: alcohol-related, invalid: neutral) and drink condition. Participants receiving a moderate dose of alcohol (0.40 g/kg) were faster to respond to alcohol-related stimuli compared with participants receiving a low dose of alcohol or placebo. These data indicate that the cognitive processes assayed by the visual probe and Stroop tasks may not be mediated by a common underlying mechanism.

Effects of alcohol consumption and alcohol expectancy on the categorisation of perceptual cues of emotional expression.

RATIONALE: Evidence that alcohol leads to increased aggressive behaviour is equivocal and confounded by evidence that such effects may operate indirectly via expectancy. One mechanism by which alcohol consumption may increase aggressive behaviour is via alterations in the processing of emotional facial cues. OBJECTIVES: We investigated whether acute alcohol consumption or the expectancy of consuming alcohol (or both) induces differences in the categorisation of ambiguous emotional expressions. We also explored differences between male and female participants, using male and female facial cues of emotional expression. METHODS: Following consumption of a drink, participants completed a categorisation task in which they had to identify the emotional expression of a facial stimulus. Stimuli were morphed facial images ranging between unambiguously angry and happy expressions (condition 1) or between unambiguously angry and disgusted expressions (condition 2). Participants (N = 96) were randomised to receive an alcoholic or non-alcoholic drink and to be told that they would receive an alcoholic or non-alcoholic drink. RESULTS: Significant effects of alcohol were obtained in the angry-disgusted task condition, but only when the target facial stimulus was male. Participants tended to categorise male disgusted faces as angry after alcohol, but not after placebo. CONCLUSIONS: Our data indicate that alcohol consumption may increase the likelihood of an ambiguous but negative facial expression being judged as angry. However, these effects were only observed for male faces and therefore may have been influenced by the greater expectation of aggression in males compared to females. Implications for alcohol-associated aggressive behaviour are discussed.